Kiss x Sis (TV) Members: 162,963 | MAL Rated 7.09 | Aired Spring 2010 | Produced by Feel That doesn't stop her (and his friends, and his classmates, and his enemies) from getting a crush on him though! This anime is the best combination of action and romance.ġ5. Strike the Blood Members: 161,547 | MAL Rated 7.44 | Aired Fall 2013 | Produced by Connect, Silver LinkĪfter being possessed by the spirit of a powerful vampire, Kojou Akatsuki is placed under observation by Yukina Himeragi, a warrior girl under orders to kill him if he becomes dangerous. However, as the series progresses, it becomes evident that whatever their motives, they are all also "crazy" in love with him! This top harem anime is full of excitement!ġ6. As he tries to buck his evil reputation, Akuto meets several girls, some of whom want to destroy him, while others want to exploit his demonic potential. Ichiban Ushiro no Daimaou (Demon King Daimao) Members: 157,030 | MAL Rated 7.21 | Aired Spring 2010 | Produced by ArtlandĪkuto Sai wants to graduate from Constant Magick Academy and enter the clergy, but he is shunned after an aptitude test declares him the future Demon King. With so many to choose from, you're sure to find your "best girl" out of these cuties!ġ7. A school comedy featuring a male main character and a lot of cute female characters, this is another "sort-of-harem" anime. Sorting out the magical mess brings them all closer together. He wishes on a magical cat statue to be able to speak up, but ends up swapping personality traits with several girls at his school. Youto Yokodera is a perverted high school student who can't express his true feelings. (The Hentai Prince and the Stony Cat.) Members: 150,585 | MAL Rated 7.46 | Aired Spring 2013 | Produced by J.C.Staff Takumi finds himself surrounded by several girls with some connection to the incidents, but can he tell what is real and what isn't?ġ8. He's forced into the real world by a series of strange events and visions surrounding a recent string of murders. Takumi Nishijou is a schizophrenic hikikomori, or recluse. ChäoS HEAd Members: 147,438 | MAL Rated 6.62 | Aired Fall 2008 | Produced by MadhouseĪ psychological harem anime based on a visual novel with an over-stylized title. This isn't the first "kiss contract" show, nor is it the only one on this list of the top harem anime.ġ9. The Sekirei and their masters battle to see who is the best. Due to a rare genetic accident, what he can do is unlock the full potential of the Sekirei-superpowered alien beings-with a kiss. Sekirei Members: 144,048 | MAL Rated 7.40 | Aired Summer 2008 | Produced by Seven Arcsġ9-year-old Minato Sahashi can't get into college because he doesn't do well under pressure. Nevertheless, it does appear to have a special part in anime history, and may just be something you want to check out.Ģ0. It's a horrible story only barely salvaged by the 'developments' that happen near the end of the story, which are shocking enough to make you think you just might've watched something of substance. This isn't a good anime, let's be clear about that. Although the story's infamous for going to some seriously dark and bizarre places, it starts off innocuously enough: high school student Makoto Itou, the most selfish and detestable protagonist in anime history, gets romantically involved with two of his classmates. Odds are that you know how this ends already, doubly so if you've played the visual novel. School Days Members: 221,490 | MAL Rated 6.17 | Aired Summer 2007 | Produced by TNK Continuations or related anime are listed as honorable mentions. If you're after a good harem anime, this is great place to start.īased on the Harem Anime Ranking Page on MAL as of the date of publication. But hey, that's not to say there aren't any gems to be found here. Despite their popularity, only 2 harem anime sit above a 8.00 score on MAL (not counting sequels). You'd think that by now, they'd have figured out a way to actually make a 'good' harem. That's the formula, and for the large part, anime has been reluctant to deviate from it in any significant way. Harem anime typically involve a large cast of girls which fall in love with the main character, often a socially inept or shy male.
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It’s used by over 2B people in more than 180 countries. WhatsApp for PC is a desktop app that can come in handy if you are regularly using the messaging platform for your work or to keep in touch with loved ones, but would prefer to do so on a much larger screen. WhatsApp from Meta is a 100 free messaging app. Moreover, downloading files is no longer an issue as it would be on smartphones that typically have less storage space. Since you can easily see any incoming calls and messages, you no longer need to constantly check your phone. This can be a problem if you are working with numerous documents that you need to share in multiple groups, and it would be great if Meta considers removing the restriction. While the mobile version allows you to initiate chats with individuals outside your contact list by tapping the New Chat icon, the desktop client lacks this feature.Īnother annoying limitation, that is also present in the mobile version, is the restriction on the forward feature that allows only up to 5 shares. A common grievance is related to how difficult it is to send a new message to someone not in your contact list. Mit der Desktop-App WhatsApp für Windows nutzen Sie wie. The WhatsApp Beta app is now available for download for Windows 10 (version 18632.0 or higher) and 11 users. On the other hand, the chat displays are organized in a new way, thanks to having more screen space.ĭespite the convenience of having the instant messaging tool on your desktop, numerous people have complained about the overall functionality of the app. Den WhatsApp-Messenger gibt es auch als kostenlose Windows-Version WhatsApp für PC. You will notice the familiar backgrounds and fonts, along with all the other elements specific to the communication tool. The interface is slightly different from the one on mobile, but not radically changed. You should be able to view and access all your conversations, groups and contacts at this point. An alternative would be to add your phone number. Wer WhatsApp im Browser nutzen will, der erhält über. News Ratgeber Vergleiche Tests 0 1:00 Min. Hier finden Sie das Programm als Download für Windows 10 und mehr. Die Whatsapp Desktop-App bringt den Messenger kostenlos auf den PC. Once you got this out of the way, simply download the app and scan the QR code provided within the interface with your phone to connect and start using WhatsApp on your desktop. WhatsApp Web 2.2410.1 Deutsch: WhatsApp Web bringt den Messenger auch in den Browser und lässt diesen damit auf nahezu jedem Gerät nutzen. Hier finden Sie das Programm als Download für Windows 10 und mehr. Known for its simplicity and user-friendly interface, it makes communication more convenient for approximately 2.7 billion users out there.Īs with any other tool that made its way from mobile to desktop, you need to already have the app up and running on your smartphone. WhatsApp is a widely used messaging app that allows you to send text messages, make voice and video calls, and share multimedia content, including photos, videos, and documents. WhatsApp Desktop - Windows App 2.2403.51. Carbon capture (part of their Energy Solutions segment) is just a small piece of that pie. But if such a strategy goes national it could be a boon to Project Bison and its backers. Fluor is a major construction company, with $13.7 billion in revenue and $427 million in earnings in FY 2022. Only California currently requires companies to participate in a cap-and-trade carbon market. Instead it hopes to sell carbon credits to other companies, getting them to pay it to sequester carbon. Unlike Fuel Cell Energy, Project Bison won’t directly make money by using CO2. Dubbed Project Bison, this complex will sequester the CO2 in deep saltwater aquifers beneath Wyoming. It was recently tapped by CarbonCapture (privately held) to help build a facility to remove CO2 directly from the air. If Fuel Cell Energy can meet these challenges, it can win big in the net zero future.įluor (NYSE: FLR) is an engineering and construction company making its own play in the carbon capture market. But its Advanced Technologies revenue shows growth and it has plenty of runway with its cash on hand. Fuel Cell Energy also needs to show it can turn a profit. However the CO2 still needs to be sequestered or it just gets released back into the atmosphere. If Fuel Cell Energy is right, then their technology can lead to net zero CO2 production when using methane as an energy source. However Advanced Technologies did show 10% growth from Q1 2022. Their total revenue was $37 million of which “Advanced Technologies” (which includes carbon capture) was $4.4 million. But the produced CO2 is in a state that makes it easier to sequester instead of releasing it into the atmosphere.įor Q1 of 2023, Fuel Cell Energy reported an operating loss of $22.4 million and cash and cash equivalents of $315 million. It’s important to realize that this process produces carbon dioxide just as much as it consumes it. That hydrogen is then used to produce electricity in fuel cells.īecause CO2 is a necessary ingredient, Fuel Cell Energy thinks its carbon capture process can be profitable. In order to obtain hydrogen, Fuel Cell Energy combines methane with CO2 at ultrahigh temperatures. While many of us learned that hydrogen and oxygen combine to produce water and energy, Fuel Cell Energy has an added twist for capturing carbon. So here’s three carbon capture stocks to keep on your radar.įuel Cell Energy (NASDAQ: FCEL) sells, leases, and maintains fuel cells for producing electricity. If the carbon capture industry proves its value, you’ll want to bet on the doers, not the talkers. By contrast, these are genuine carbon capture stocks that actually capture carbon. While many companies talk about carbon capture, very few actually do it. And that means understanding both the science and economics of carbon. Thus a successful carbon capture stock needs to have a strong vision of what they can accomplish profitably. But sequestration is difficult and CO2 has proven less useful than advocates had wished. Without profit, carbon capture can’t create a virtuous cycle of growth and development.Ĭarbon capture is the process of removing CO2 and either using it for something else or sequestering it. However, in order to achieve those objectives, carbon capture will need to be prove itself profitable. Not only that, the Biden Administration has already pledged $3.7 billion to help kickstart the industry and achieve climate objectives. With the world trying to reach net zero carbon emissions, carbon capture stocks have taken center stage. one, two or even four wheels at the front capable of steering), the vehicle's turning diameter measures the minimum space needed to turn the vehicle around while the steering is set to its maximum displacement from the central 'straight ahead' position - i.e. On wheeled vehicles with the common type of front wheel steering (i.e. The terms ( radius, diameter, or circle) can have different meanings refer to the § Alternative nomenclature section.ĭefinition Diagram of turning vehicle. The term thus refers to a theoretical minimal circle in which for example an aeroplane, a ground vehicle or a watercraft can be turned around. The Oxford English Dictionary describes turning circle as "the smallest circle within which a ship, motor vehicle, etc., can be turned round completely". The turning radius (alternatively, turning diameter or turning circle) of a vehicle defines the minimum dimension (typically the radius or diameter, respectively) of available space required for that vehicle to make a semi-circular U-turn without skidding. A vehicle with a smaller turning diameter will be able to perform a sharper U-turn. ( Learn how and when to remove this template message)ĭiagram showing the path of a driver performing a U-turn. JSTOR ( April 2021) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification. To date your Longines watch, you can either take help from the serial number list below or identify the age and production year of your vintage Longines watch by ordering a certificate of authenticity or extract from the archives directly from Longines. The serial number may also be engraved on the movement. Most often, the number is engraved on the outside of the case back, but in some cases, it may be engraved on the inside, which means you need to remove the case back in order to access it. Longines serial numbers can normally be found engraved on the case back. The serial number consists of 5 to 8 digits. We will go more into detail about this further on. What is even more interesting (and something we have Longines to thank for), is that Longines is happy to share this information with the public.Ĭompanies like Rolex naturally have a well-recorded database of their serial numbers, but do not disclose this information to the public as Longines does. Using its record, Longines can provide first-class and detailed information about the timepieces that have left the factory. Safe to say that is quite a substantial record. In fact, Longines has recorded every single serial number of its watches since 1867. Longines serial numbersįew manufacturers keep as well-recorded records about their watches as Longines. With the help of the serial number, you can date your Longines watch, and we will go into detail about how you can do that further on. This allows them to get detailed information about the watches.Īn example of such information is dating the production time of the watch. Primarily, the serial number is used to help the manufacturer to keep track of every single watch that leaves the factory. The serial number is unique to every single watch and is used for a number of different reasons. This is no exception for Longines watches. The vast majority of watches are equipped with serial numbers. From winning the Grand Prix at the Universal Exhibition in Paris in 1900 to being the official timekeeper for Formula 1 for 10 years, and much more in between. Founded in 1832, Longines has achieved and done a lot over the course of its history. Year of production is likely to be earlier.Longines is one of the oldest Swiss watch brands in the world. So, does that make this pocket watch of 1889 or 1911? Because invoicing a watch on a date doesnt mean the year of production. Now, that is some record keeping and archiving! Hopping this information is convenient to you, I remain at your entire disposal for any additional information you may require. It was invoiced to Messrs.’ Perusset, who were for many years our agent for Argentina, on. It is fitted with a Longines manufacture caliber 18.50 that was first produced in 1889. Following your request, I have the pleasure to give you here below the information I found in our old hand-written registers : The serial number 2'422'066 identifies a hunter pocket watch in silver 0.900. " Dear XXXXXX Thank you for your email and interest in Longines watches. I wrote to Ms Jennifer as suggested and took her permission to quote her reply verbatim on this site. My God Peter, where were you all the while ? What the mark on the left hand side of the case is I cannot fathom out and I daresay we will never know.Īt the end of the day you have a very nice watch made by a respectable manufacturer - enjoy it.Īpologies Jerry - was busy typing this out and removing typo's and posted it without realising you had posted a reply. The case bears (no pun intended) Swiss hallmarking (not British) in the form of the bear rampant and has a silver content of 90%. So all in all you have a movement from 1909 - 1911 in a case manufactured post 1906. The other scenario to that of course is that cases made before that date were held in stock and susbsequently used with that inscription applied - probably unlikely but the posssibility is there. That fits in nicely with your case - even though your movement appears to have been recased as Graham pointed out earlier in this thread - in that the case, in theory, would have been made either in or after 1906 otherwise the accolades of winning four prizes could not have appeared. It dates (approximately) the manufacture of your movement to between 19. POM have a look at this link which I found using a search engine (Google is your friend on this occasion) Despite its difficulty, the game is very popular among solitaire fans, who enjoy the challenge and the satisfaction of successfully completing the game. It requires a great deal of strategy and patience, as well as a good memory, as players must remember where certain cards have been placed in order to make the best moves. Spider Solitaire is known for its high level of difficulty, as players must carefully plan their moves in order to complete the game. The remaining cards form the stock pile, which can be used to fill empty tableau piles. The game starts with ten tableau piles, with the first four having six cards each and the remaining six having five cards each, all arranged in a specific pattern. The goal of the game is to move all the cards to eight foundation piles, four of which are based on suit and in ascending order (Ace to King) and the other four are based on suit and in descending order (King to Ace). Spider Solitaire is a popular single player card game that is played with two decks of cards (104 cards total). A full descending suit pack must be made on the tableau, and then that pack will move to the first empty foundation pile. Cards cannot be moved to foundation piles directly.Ten foundation piles that must be filled by full descending suits.For example, a 9 8 7 pack may move to a pile with 10, as long as they are all the same suit. Only packs of cards that are of the same suit can be moved as a set. Packs of cards can also be moved between piles if they continue a descending order from the fully visible face up card on the pile they are moving to.For example, a 9 can be placed on top of a pile that has a 10 card face up. Cards can be moved between piles if they are one rank lower than the fully visible face up card on the pile they are moving to.The next six piles start with five cards. There is only one full pass through the stock.Can only be dealt if all piles in tableau have cards in them.The game is won once all cards are in the foundation. Once a full sequence of ranks with the same suit is built, it automatically moves to the foundation (cards cannot be placed on the foundation individually). We don't recommend doing this before you're completely sure there are no moves left.Sort cards on the tableau so they are in descending order, from King to Ace. That will move ten cards from the stock down to the tableau, placing one card on each tableau. When you have no more moves to make on the tableau, you can click on the stock in the top left corner. You can move any card or partial run to an empty tableau spot if you have one. After that, you'll have to move them one at a time. You can't move them together if you have the eight of spades, the seven and six of clubs. For example, if you have the eight of spades through the six of spades, you can click and drag them all to a nine of hearts. If all of the cards in a run have the same suit, you can move them all simultaneously. Only if the sequence of cards is of the same suit will this happen. Once you have a complete sequence of cards, they will be moved to the foundation. The game's goal is to make runs of cards from king to ace in the same suit. As a result, different suits of cards can be stacked on top of one other. For example, if you have seven spades, you can put it on eight spades or eight of any other color. Cards can always be moved to a higher-ranking card. To get cards from the tableau onto the foundation, you have to rank them from king to ace on the tableau. The foundation: This is where you want all your cards to end up ordered by suit and rank.The stock: This is the pile of cards face down from which you draw.The tableau: This is where you'll make most of your moves.The layout of the game can be divided into three main areas: The goal of the game is to remove all cards from the tableau and on to the foundation piles. Unlike other solitaire games, this one is played with two decks of playing cards. I used to worry only about being the biggest and now I worry about looking my best no matter my weight. The “Jiggle Test” is a quick check to satisfy our longing to be better. I too use Arnold’s “Jiggle Test” and sometimes it jiggles and at other times I am firm. If they are visible I am happy, if not I am driven to make them better. I look down at my abs to see if they are visible. I always try to do better with each workout, cardio session, posing session, and with the food he prescribes for me. My greatest respect I can give him is to be my best and give my best. I’m a bodybuilding neophyte still trying to put my trunks on frontwards, but he has steadied me as make mistakes. But, like Justin says, “I like being your friend, but sometimes I have to be your coach.” Enough said! Justin has pushed me to be better and has shared his knowledge and expertise without reserve. My poor ego has been many times bruised during prep. My coach Justin Dees sees me as I am and he will tell what I need to hear and he is brutal. Well, that’s giving me way too much credit for knowing anything. When I look at myself in the mirror as I pose it seems like every deficiency jumps back at me and I again cringe. This immediately gives us a status report. The best way to tell if we are making progress is the weekly weigh in and body fat measurement by our coaches. However, all of us who compete in bodybuilding knows that the scale is only one measure of our progress. Sometimes I cringe and other times I feel like doing cart wheels all the way back to my bed. I sort of look down at the scale with one eye closed and the other squinting to the daily weight reading. I weigh myself “every” morning as soon as I get out of bed. The competitors, the coaches, the judges, the families are all impacted by the requirement to be in the best shape of our lives the day we compete. Being shredded is the demand that is placed on all of us who do bodybuilding. As I push through my prep for 2018 there is this constant pressure (often self inflicted) to be leaner and more shredded. “Compare hydrogen with kerosene, it has three times the amount of energy,” explains Kavanagh. Initially, hydrogen will be used in gaseous form. The hydrogen-powered planes envisaged to be in the skies above Britain from 2025 are little more than a stepping stone. Those involved with Napkin say that their proposals will form the basis of the UK’s answer to decarbonising air travel, in the same way that similar government-commissioned reports provided the framework for the ban on the sale of petrol and diesel cars by 2030. But in the UK, as other sectors reduce their footprint and air travel continues to grow, the industry is on course to produce 39pc of greenhouse gas emissions by 2050. “While other solutions were looked at initially, such as electric and hybrid propulsion, the consortium concluded that hydrogen technologies provide the path to zero-carbon emission flight for mainstream commercial services.”Īirlines have been blamed for their role in the climate crisis as activists such as Greta Thunberg campaigned against the industry through the Flygskam, or flight-shame, movement.īetween 2pc and 3pc of carbon emissions are generated by the global aviation industry. “Hydrogen aircraft represent a credible solution to reach zero carbon flight and are the natural complement to sustainable aviation fuels,” the blueprint says. The plans pour cold water on electric-powered aircraft playing a central role in “guilt-free flying” - this despite airlines such as easyJet previously identifying electric-powered as the answer to reducing the industry’s carbon footprint. These early flights will be operated by retrofitted planes carrying gaseous hydrogen in tanks beneath their wings.įrom 2035, a new fleet of aircraft designed specifically to run on hydrogen could fly the entire domestic schedule from regional airports such as London City, according to the blueprint, which will be unveiled at the UN’s Cop27 climate change conference in Egypt this week.Īnd by 2040, 90-seater hydrogen-powered jets are scheduled to be in service, meaning the entire UK domestic aviation market will be operated by zero-emissions planes. The Napkin blueprint, seen by The Telegraph, has been developed by a coalition of industry experts from the likes of Cranfield Aerospace, Rolls-Royce, GKN, and Heathrow airport, as well as academics from University College London and Southampton University.Īccording to Napkin, hydrogen flights carrying up to 19 passengers between the Scottish islands and the mainland could be a reality between 20. Kavanagh is among a group of British scientists involved in a government-backed initiative codenamed “Project Napkin”, which has plotted a course to providing Britain with net-zero flights. “The hydrogen was gone before the photographer turned up.” “The flames of the Hindenburg disaster were all about the canopy,” she adds. It’s just different,” says Jenny Kavanagh, chief strategy officer at Cranfield Aerospace Solutions. And hydrogen is no less or more dangerous. The television footage of the fireball, coupled with journalist Herbert Morrison’s commentary, helped cement hydrogen’s reputation as a dangerous fuel.īut this stigma baffles those that believe it is the answer to weaning air travel off fossil fuels. Shortly before 7.30pm on May 6, 1937, the Zeppelin airship burst into flames killing 36 people as it attempted to dock in New Jersey. The fallout from the Hindenburg disaster has cast a 85-year-old shadow over the aviation industry’s plans to use hydrogen fuels. Sweet haveĪll addressed the Catholic elements in “The Cask of Amontillado.” (3) Felheim speculates that theĬatholic Montressor despises Fortunato in part because the soon to be entombed man is a Mason. Marvin Felheim, Donald Pearce, Kathryn Montgomery Harris, James E. More recent commentators have made a few cursory studies of Poe and Roman Catholicism, usually focusing on theĬatholic-Masonic feud. Moment, I will state only that Forrest failed to see the significance of some of his own remarks. Later in this discussion, I will refer to some of the facts pointed out by Forrest. Poe’s characters “are good Roman Catholics.” Forrest goes on to say, “since he was a romanticist the phases ofįormal religion that attracted Poe most naturally were Catholic.” (2) Unfortunately, Forrest does notĮlaborate on these intriguing points. In Biblical Allusions in Poe, he remarks that many of Regrettably does not follow up on some of his most intriguing assertions. Yet interesting study published in 1928, William Mentzel Forrest verges on the brink of firmly linking Poe to Catholic tradition, but To date, no scholar seems to have examined in depth Poe’s familiarity with Roman Catholicism. More to our point, it appears that the Church of Rome did not escape the attention or interest (1) As we shall see, far from being a “forgotten church,” Roman Catholicism played an active, indeed prominent role Working knowledge of - perhaps even a sympathy for - a number of the Church’s basic teachings. Indeed, a careful evaluation of Poe’s literary legacy suggests that Poe possessed a good As with so many aspects of Poe’s writings, however, the On Poe’s part of the Catholic Church as a mere curious artifact. Here we are faced with what a casual reader might regard as a notable dismissal “the manual of a forgotten church” (M2:409). Secundum Chorum Ecclesiae Maguntinae ( Vigils for the Dead according to the Use of the Church of Mainz), a Roman Catholicīook of prayers for the dead referred to by Usher’s friend as This work, so we are told, served as Roderick’s “chief delight.” It is The Vigilae Mortuorum Treatises dealing with the occult, torture, and demonology - not exactly ideal material for relaxation.Īlthough the complete contents of the Usher family library are worthy of scholarly attention, one curious tome merits But what sort of books do we find on Roderick’s shelves? Usher’s study abounds with Poe’s speaker believes that reading to Roderick will help his friend “nervous agitation” deserves special notice. Unidentified condition which has elicited various explanations from scholars over the years. Most naive (and one of the luckiest) figures in American fiction, does his best to help Roderick survive a mysterious malady, an That the head of the Usher family was Poe’s nineteenth-century version of Jimi Hendrix. Her brother, theĬadaverous Roderick Usher, passes his time with wild improvisations on the guitar, which once prompted a student of mine to conclude Madeline Usher, for example, can only be described as a woman of few words. Almost immediately, the reader of this tale is confronted by a number of characters who mustĬertainly be considered quite peculiar. Few would disagree, at least, that it is one of Poe’s most One of the greatest short stories in all of world literature. MANY READERS CONSIDER EDGAR ALLAN POE’S “The Fall of the House of Usher” to be After ACE, the head region is fixed at the dorsal equatorial region, and the notochord is formed posteriorly through the vegetal pole (Fig. In the case of Xenopus laevis, ACE occurs in the first 3 h of the whole 20-h process of gastrulation at 13 ☌. 1d), at which the whole region of neural tissues is determined. The developmental stage when the physical contact between the anterior-most neuroectoderm and the head organizer occurs is called “anterior contact establishment (ACE)” (Fig. Subsequently, the prospective neuroectoderm and the organizer become closer to establish physical contact with each other by subduction and zippering (S&Z) movement, which is probably performed by the combination of both epiboly (Keller 1978) and vegetal rotation (Winklbauer and Schürfeld 1999) (Fig. Eventually, the organizer tissue is located at the dorsal portion of the blastocoel floor by the onset of gastrulation (Fig. Both tissues move downward to the equatorial region by epiboly movement (Keller 1978). Briefly, the organizer is originally located in the blastocoel roof of the blastula adjacent to the prospective neuroectoderm around the animal pole (Fig. 2015) which is totally different from the conventional model drawn in a wide variety of both scientific papers and textbooks. Previously, we proposed an amphibian gastrulation model (Fig. Thus, it has been considered so far that the direction of notochord formation is opposite between amphibians and avians, and therefore, it is difficult to discuss the evolution of the morphogenetic movement. However, whereas the amphibian dorsal blastopore lip is thought to form a notochord anteriorly by animalward migration on the inner surface of the blastocoel roof, the chick Hensen’s node migrates and forms a notochord posteriorly. Therefore, these tissues are considered the equivalent structure, termed the organizer. 1997), and both tissues show a potent secondary axis-inducing ability upon transplantation (Spemann and Mangold 1924 Leikola, 1976). 1993 Smith and Harland 1992 Connolly et al. For example, the amphibian dorsal blastopore lip and the chick Hensen’s node express the same genes, such as goosecoid and noggin (Cho et al. While the molecular mechanisms involved in gastrulation are thought to be conserved among vertebrates, the morphogenetic movement is described as divergent. Gastrulation is a critical developmental event for producing three germ layers, three body axes, and the central nervous system in the embryo. Finally, by comparing amphibian gastrulation to gastrulation of protochordates and amniotes, we discuss the gastrulation movement evolutionarily conserved among chordates. Collectively, these results are consistent with the S&Z gastrulation model and identify the embryonic region sufficient for construction of the complete dorsal structure. Furthermore, a blastocoel roof explant of the blastula, which should contain the organizer and the prospective neuroectoderm in the S&Z model, autonomously underwent gastrulation and formed the complete dorsal structure. To investigate this possibility, we conducted stepwise tissue deletions using Xenopus laevis embryos and revealed that the dorsal one-third of the marginal zone had the ability to form the complete dorsal structure by itself. According to this model, the body axis is derived from limited regions of the dorsal marginal zone at ACE. The developmental stage when contact between the head organizer and the anterior-most neuroectoderm is established is called “anterior contact establishment (ACE).” After ACE, the A-P body axis elongates posteriorly. In this model, the organizer and the prospective neuroectoderm are originally localized in the blastula’s blastocoel roof, and these embryonic regions move downward to make physical contact of their inner surfaces with each other at the dorsal marginal zone. Previously, we proposed a novel amphibian gastrulation model, the “subduction and zippering (S&Z) model”. However, the morphological movement during gastrulation appears to be divergent across species, making it difficult to discuss the evolution of the process. Gastrulation is a critical event whose molecular mechanisms are thought to be conserved among vertebrates. |
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