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Secrets of frog killer laid bare


By Richard Black
Environment correspondent, BBC News website

Scientists have unravelled the mechanism by which the fungal disease chytridiomycosis kills its victims.

The fungus is steadily spreading through populations of frogs and other amphibians worldwide, and has sent some species extinct in just a few years.

Researchers now report in the journal Science that the fungus kills by changing the animals' electrolyte balance, resulting in cardiac arrest.

The finding is described as a "key step" in understanding the epidemic.

Karen Lips, one of the world authorities on the spread of chytridiomycosis, said the research was "compelling".

"They've done an incredible amount of work, been very thorough, and I don't think anybody will have problems with this.

"We suspected something like this all along, but it's great to know this is in fact what is happening," the University of Maryland professor told BBC News.

 Signs of infection. Researchers found that chytrid infection on the frogs' undersides became fatal above a certain "load" of spores - backing findings from other research groups.

Skin deep

Amphibian skin plays several roles in the animals' life.

Most species can breathe through it, and it is also used as a membrane through which electrolytes such as sodium and potassium are exchanged with the outside world.

The mainly Australian research group took skin samples from healthy and diseased green tree frogs, and found that these compounds passed through the skin much less readily when chytrid was present.

Samples of blood and urine from infected frogs showed much lower sodium and potassium concentrations than in healthy animals - potassium was down by half.

In other animals including humans, this kind of disturbance is known to be capable of causing cardiac arrest.

The scientists also took electrocardiogram recordings of the frogs' hearts in the hours before death; and found changes to the rhythm culminating in arrest.

Drugs that restore electrolyte balance brought the animals a few hours or days of better health, some showing enough vigour to climb out of their bowls of water; but all died in the end.

Hundreds of amphibian species will become extinct unless a global action plan is put into practice very soon, conservationists warn. (Image: Glass tree frog - R.D.Holt)
Campaigners are forming an Amphibian Survival Alliance to carry through a rescue strategy. (Image: Centrolene tayrona - Fundacion Pro aves)
There are about 6,000 known amphibians, a category that includes frogs, toads, salamanders and caecilians (legless amphibians). (Image: Albericus siegfriedi - S.Richards)
More than a third of all amphibian species are said to be in peril. (Image: Golden mantella - R.A.Mittermeier)
The two main threats are habitat loss and the fungal disease chytridiomycosis. Climate change, hunting and pollution are other issues of concern. (Image: Sphenophryne cornuta - S.Richards)
In particular, the fungus Batrachochytrium dendrobatidis, first identified 1998, is doing widespread damage in parts of the Americas, Australia and Europe. (Image: Nimbaphrynoides occidentalis - P.Naskrecki)
The new Amphibian Survival Alliance will co-ordinate conservation efforts with a particular interest in field treatments for the chytrid fungus. (Image: Dendrobates azureus - R.A.Mittermeier)
"We simply cannot afford to let this current amphibian extinction crisis go unchecked," said Simon Stuart, chair of IUCN's Species Survival Commission. (Image: Centrolene tayrona - Fundacion Pro aves)


Grail quest

Lead scientist Jamie Voyles, from James Cook University in Townsville, said the next step was to look for the same phenomenon in other species.

"This is lethal across a broad range of hosts, whether terrestrial or aquatic, so it's really important to look at what's happening in other susceptible amphibians," she said.

Another step will be to examine how the chytrid fungus (Batrachochytrium dendrobatidis - Bd) impairs electrolyte transfer.

"What this work doesn't tell us is the mechanism by which chytrid causes this problem with sodium," said Matthew Fisher from Imperial College London.

"It could be that Bd is excreting a toxin, or it could be causing cell damage. This causative action is actually the 'holy grail' - so that's another obvious next step."

The finding is unlikely to plot an immediate route to ways of preventing or treating or curing the disease in the wild.

Curing infected amphibians in captivity is straightforward using antifungal chemicals; but currently there is no way to tackle it outside.

Various research teams are exploring the potential of bacteria that occur naturally on the skin of some amphibians, and may play a protective role.

Understanding the genetics of how Bd disrupts electrolyte balance might lead to more precise identification of protective bacteria, suggested Professor Lips, and so eventually play a role in curbing the epidemic.

 Ways to stop chytrid in the wild are the "holy grail" for researchers




Lizards filmed 'walking on water'




By Matt Walker
Editor, Earth News


A "Jesus Christ" lizard, filmed from above and below the water

Remarkable slow-motion footage has been taken of two lizards that seem to do the impossible - walk on water.

A high-definition film, shot at 2,000 frames per second, shows a brown basilisk lizard running across the surface of a pond in Belize.

More footage shows how a species of gecko is so tiny that it can walk across a puddle without breaking the water's surface tension.

These amazing feats are captured for the BBC natural history series Life.

The group of animals known as basilisk lizards commonly lives along the edge of rivers running through rainforests, eating small insects among the foliage.

The lizards need to bask in the sun to warm up each day, which leaves them vulnerable to being caught by predators, such as large birds of prey hunting from the air, or carnivores such as cats living on the jungle floor.

So the lizards have evolved an extraordinary escape mechanism.

They drop into the water and then run across it, earning the lizards their nickname, the "Jesus" or "Jesus Christ" lizard.

Exactly how they do so is revealed by the slow-motion, high-definition footage taken at 2,000 frames per second.

"Because they run so fast they create a bubble as their feet hit the water and then they push off from this bubble before it bursts," says Simon Blakeney, a producer on the Life series who helped direct and film the footage of both reptiles.

"They can only run at that speed. If they were going any slower, for example, they wouldn't stay upright, they would slip into the water and would have to swim."

Mr Blakeney and his colleagues filmed brown basilisk lizards (Basiliscus vittatus) running across ponds and rivers in the rainforest in Belize, around 60km from Belize City.

Capturing the footage of the animals in action proved tricky.


To a Brazilian pygmy gecko, a raindrop could be deadly

"Around 80% of the time when they are escaping from things, they don't run, they swim. So filming them running was quite a difficult thing in itself."

The lizard has long thin toes that are covered by scales underfoot. These help create the air bubbles that enable the lizard to push off and walk across the water.

Scientists had also previously established that basilisk lizards produce massive sideways forces in their running stride, which, perversely, help them stay upright.

Slowing the action of the film to 1/80th of its real-life speed reveals the true spectacle, says Mr Blakeney.

"As the water lifts up it makes this incredible trail of splashes behind it, like a pebble dropping into the water.

"Then the lizard has already gone out of frame because they are so fast."

Float like a gecko

Another lizard, a tiny species known as a pygmy gecko, faces a different problem altogether.

At just 2 to 4cm long from head to tail, the Brazilian pygmy gecko (Coleodactylus amazonicus) could be battered by a raindrop and risk drowning in even the smallest pool of water.

So it has evolved to be essentially waterproof, which in turn allows it to walk across the surface of any puddle it encounters.

Mr Blakeney's team encountered the remarkable gecko near a place called Aripauna, on the edge of the Amazon in Brazil.

With the help of expert Dr Gabriel Skuk of the Federal University of Alagoas based in Maceio, Brazil, the team filmed the geckos surviving in the leaf litter on the forest floor.

"They don't really use water as an escape response, because even if they are trying to escape from something a puddle looks like a lake to them," says Mr Blakeney.

"Because they are so tiny, they are able to float on the surface of the water like a pondskater, so they don't break the surface tension.

"I've never seen anything like that to be honest."

The geckos have hydrophobic skin which repels water just like a waterproof jacket.

One hypothesis put forward by scientists, says Mr Blakeney, is that as the geckos became smaller, they needed to evolve a way to float, to avoid drowning when it rains.

The water-walking lizards can be seen on the BBC series Life, which is broadcast at 2100BST on BBC One on Monday 19 October.



Legless frogs mystery solved




Matt Walker
Editor, Earth News


Deformed toads, each a product of 'selective predation'


Scientists think they have resolved one of the most controversial environmental issues of the past decade: the curious case of the missing frogs' legs.

Around the world, frogs are found with missing or misshaped limbs, a striking deformity that many researchers believe is caused by chemical pollution.

However, tests on frogs and toads have revealed a more natural, benign cause.

The deformed frogs are actually victims of the predatory habits of dragonfly nymphs, which eat the legs of tadpoles.

In the late 1980s and early 1990s, researchers started getting reports of numerous wild frogs or toads being found with extra legs or arms, or with limbs that were partly formed or missing completely.

The cause of these deformities soon became a hotly contested issue.

Some researchers believed they might be caused naturally, by predators or parasites.

Others thought that was highly unlikely, fearing that chemical pollution, or UV-B radiation caused by the thinning of the ozone layer, was triggering the deformations.

"Deformed frogs became one of the most contentious environmental issues of all time, with the parasite researchers on one side, and the 'chemical company' as I call them, on the other," says Stanley Sessions, an amphibian specialist and professor of biology at Hartwick College, in Oneonta, New York.

"There was a veritable media firestorm, with millions of dollars of grant money at stake."

After a long period of research, Sessions and other researchers established that many amphibians with extra limbs were actually infected by small parasitic flatworms called Riberoria trematodes.

These creatures burrow into the hindquarters of tadpoles where they physically rearrange the limb bud cells and thereby interfere with limb development.

"But that was not end of the story," says Sessions.

"Frogs with extra limbs may have been the most dramatic-looking deformities, but they are by far the least common deformities found," he explains.

"The most commonly found deformities are frogs or toads found with missing or truncated limbs, and although parasites occasionally cause limblessness in a frog, these deformities are almost never associated with the trematode species known to cause extra limbs."


Missing legs

The mystery of what causes frogs to have missing or deformed limbs remained unsolved until Sessions teamed up with colleague Brandon Ballengee of the University of Plymouth, UK. They report their findings in the Journal of Experimental Zoology Part B: Molecular and Developmental Evolution.

For a decade, Ballengee and Sessions have collaborated on a series of art and science projects that image amphibians' bodies to show the detail within, the most recent of which is funded by the Arts Catalyst organisation, based in London.


As part of this work, Ballengee and Richard Sunter, the official Recorder of Reptiles and Amphibians in Yorkshire, spent time during the summers of 2006 to 2008 surveying the occurrence of deformities in wild amphibians at three ponds in the county.

In all, they found that between 1.2% and 9.8% of tadpoles or metamorphosed toads at each location had hind limb deformities. Three had missing eyes.

"We were very surprised when we found so many metamorphic toads with abnormal limbs, as it was thought to be a North American phenomenon," says Ballengee.

While surveying, Ballengee also discovered a range of natural predators he suspected could be to blame, including stickleback fish, newts, diving beetles, water scorpions and predatory dragonfly nymphs.

So Ballengee and Sessions decide to test how each predator preyed upon the tadpoles, by placing them together in fish tanks in the lab.

None did, except three species of dragonfly nymph.

Crucially though, the nymphs rarely ate the tadpoles whole. More often than not, they would grab the tadpole and chew at a hind limb, often removing it altogether.

"Once they grab the tadpole, they use their front legs to turn it around, searching for the tender bits, in this case the hind limb buds, which they then snip off with their mandibles," says Sessions.


Stunted growth

Remarkably, many tadpoles survive this ordeal.

"Often the tadpole is released and is able to swim away to live for another day," says Sessions. "If it survives it metamorphoses into a toad with missing or deformed hind limbs, depending on the developmental stage of the tadpole."

If tadpoles are attacked when they are very young, they can often regenerate their leg completely, but this ability diminishes as they grow older.

The researchers confirmed this by surgically removing the hind limbs of some tadpoles and watching them grow. These tadpoles developed in an identical way to those whose limbs had been removed by dragonflies, confirming that losing a limb at a certain stage of a tadpole's development can lead to missing or deformed limbs in adulthood.

Adult amphibians with one one hind limb appear able to live for quite a long time, Sessions says, explaining why so many deformed frogs and toads are discovered.

Why do the dragonflies like to eat the hind legs only?



A normal and a legless toad stained to reveal details of the skeletal deformities (bones purple, cartilage blue, soft tissues transparent).


As toad tadpoles mature, they develop poison glands in their skin much earlier than those in their hind legs, which could make the hind legs a far more palatable meal.

The front legs of tadpoles also develop within the gill chamber, where they are protected.

Sessions is careful to say that he doesn't completely rule out chemicals as the cause of some missing limbs. But 'selective predation' by dragonfly nymphs is now by far the leading explanation, he says.

"Are parasites sufficient to cause extra limbs?," he asks. "Yes. Is selective predation by dragonfly nymphs sufficient to cause loss or reduction of limbs. Yes. Are chemical pollutants necessary to understand either of these phenomena? No."


From: http://news.bbc.co.uk/earth/hi/earth_news/newsid_8116000/8116692.stm

25 June 2009 10:48 UK



珠海二百鱷魚大逃亡 恐順水入港危及大嶼山













新浪科技訊 北京時間7月24日消息,據英國《每日電訊報》報導,“寂寞的喬治”是一隻巨大的加拉帕戈斯陸龜,數十年來一直獨自生活。如今它竟然有了意中“龜”,這讓公園的管理員們大為吃驚。








新浪科技訊 北京時間7月3日消息,據國外媒體報導,科學家目前正為全球最後一隻被世人所熟知的加拉帕哥斯陸龜——“寂寞的喬治”尋找配偶。但是,一些人卻表示這種避免物種滅絕的努力可能是徒勞的。








東方網08年6月26日- 百年巨鱉



四川地震 - 有關出現大量蟾蜍 的新聞

2008年06月20日-大量小蟾蜍橫穿馬路 專家稱屬正常遷徙

本報訊 (記者 沈麗莉 黨小軍)兩天來,每到傍晚,在西固區東川鄉的一些路段上,都會出現小蟾蜍浩浩蕩蕩橫穿馬路的景象,蟾蜍大量聚集讓附近村民聯想到這是不是什麼天災的徵兆。就此,西固區地震局專門派出工作人員現場查看,同時本報記者採訪了生物學專家,他們全部判定,東川鄉的蟾蜍聚集只是一種正常的現象。



2008年06月19日-上萬蟾蜍馬路邊聚會 專家稱為出行納涼

昨晚,五O四廠附近,大量小蟾蜍結隊過馬路 張言 攝
小蟾蜍出遊 居民好奇
傍田靠水 萬隻蟾蜍排長龍
就上述情況,記者採訪了蘭州大學教授、動物專家劉迺發。他在聽取了記者的現場採訪過程及瞭解了蟾蜍出沒地的環境後作出了解釋。他解釋,夏天炎熱,特別是陰天時,小蟾蜍在下午和傍晚排隊轉移實際是在尋找更加涼爽透氣的環境。而且從周圍環境來看,小蟾蜍白天活動在農田、樹林堙A到了傍晚都出來找涼快,市民自然會感覺這些小傢伙的數量激增,出現列隊前進的場面。 (本文來源:西部商報 作者:吳樹權 宋芳科)



2008年05月24日-深圳街邊出現大量蟾蜍 地震局電話被打爆

南方網5月24日報導 深圳西麗街道珠光南路近日出現大量蟾蜍,引起市民高度關注,深圳市地震局諮詢電話被打爆,有些線民稱已報警。昨日,深圳市地震局通過現場調查、儀器檢測和觀察資料與省地震局核對後得出結論:西麗出現大量蟾蜍屬繁殖期正常現象,深圳近期發生破壞性地震的可能性很小。
據地震局介紹,深圳目前已經建成數位遙測地震台網和強震台網,可以及時監測到深圳和周邊地區地震發生的時間、地點和級數。(南方都市報) (本文來源:南方網 作者:程文)




蜜蜂群遷鬧轟轟,鴿子驚飛不回巢。 (本文來源:和訊網 )


盤踞海邊 10 呎蛇遭制服

盤 踞 海 邊 10 呎 蛇 遭 制 服
人 蟒 大 戰 一 分 鐘

一 條 大 蟒 蛇 昨 趁 天 氣 回 暖 , 在 香 港 仔 華 貴 村 對 開 海 邊 曬 太 陽 , 警 員 接 報 在 旁 戒 備 。

【 本 報 訊 】 雖 然 明 日 才 到 驚 蟄 , 但 一 條 長 達 10 呎 的 大 蟒 蛇 昨 已 趁 天 氣 回 暖 , 在 香 港 仔 華 貴 對 開 海 邊 曬 太 陽 。 警 方 接 報 到 場 , 發 現 該 條 蟒 蛇 離 奇 地 被 膠 布 纏 頭 部 , 但 仍 能 張 牙 吐 舌 , 十 分 嚇 人 。 警 方 召 來 「 蛇 王 」 經 一 番 搏 鬥 將 牠 制 服 , 轉 交 漁 護 署 處 理 。 記 者 : 羅 日 昇

現 場 為 華 貴 對 開 雞 籠 灣 岸 邊 防 波 堤 , 昨 午 1 時 許 , 有 民 見 一 條 長 10 呎 , 直 徑 近 呎 大 蟒 蛇 在 堤 壩 邊 大 石 上 盤 成 蛇 餅 , 雖 然 頭 部 被 膠 布 纏 , 但 間 中 仍 張 開 大 口 , 露 出 尖 牙 及 舌 頭 , 民 報 警 。 警 方 到 場 , 一 方 面 準 備 好 運 蛇 鐵 籠 , 一 方 面 電 召 蛇 王 陳 振 福 到 場 。
不 久 , 手 持 4 呎 長 連 鐵 枝 的 陳 到 達 , 他 以 為 此 蛇 容 易 對 付 隨 即 走 近 蟒 蛇 身 邊 , 雙 手 握 住 蛇 頸 試 圖 將 牠 扯 入 準 備 好 的 布 袋 內 , 但 蟒 蛇 力 大 非 常 , 全 身 不 斷 擺 動 與 他 搏 鬥 。 人 蛇 大 戰 隨 即 展 開 。 在 旁 警 長 見 狀 立 即 用 腳 踩 住 蛇 尾 , 減 低 其 活 動 能 力 , 結 果 經 一 分 多 鐘 爭 鬥 , 蟒 蛇 被 塞 入 布 袋 再 推 進 鐵 籠 , 由 多 名 警 員 將 鐵 籠 抬 走 , 交 漁 護 署 處 理 。 蟒 蛇 在 港 屬 受 保 護 動 物 , 料 稍 後 會 被 放 歸 大 自 然 。
蛇 王 陳 事 後 對 要 花 一 番 努 力 才 能 將 蟒 蛇 制 服 說 : 「 呢 條 係 緬 甸 蟒 , 仲 百 斤 重 , 好 大 力 , 估 佢 有 過 百 歲 呀 , 捉 佢 真 係 要 鬥 智 鬥 力 … … 」

蟒 蛇 頭 部 被 膠 布 纏 , 原 因 不 明 。

蛇 王 被 召 到 場 , 經 一 番 角 力 後 , 終 將 蟒 蛇 制 服 。 羅 日 昇 攝

數 名 警 員 將 裝 有 蟒 蛇 的 大 鐵 籠 抬 走 。

去 年 西 貢 蛇 吞 羊

據 資 料 稱 , 10 呎 蟒 蛇 屬 中 等 類 別 , 一 般 壽 命 約 20 年 , 在 香 港 只 有 緬 甸 蟒 一 種 , 每 年 驚 蟄 後 出 來 活 動 , 初 夏 尤 為 活 躍 。 去 年 5 月 26 日 , 西 貢 井 欄 樹 曾 出 現 一 條 大 蟒 蛇 將 一 頭 小 黑 羊 活 活 纏 死 , 然 後 將 之 吞 下 再 吐 回 羊 頭 , 十 分 可 怖 。
據 華 貴 居 民 說 , 他 們 不 時 都 在 海 邊 見 過 大 蟒 蛇 , 並 曾 見 過 流 浪 貓 被 吞 噬 。 平 日 有 很 多 民 會 到 海 邊 釣 魚 , 甚 至 有 人 在 該 處 海 邊 游 泳 , 「 如 果 有 蛇 石 罅 捐 出 , 就 大 件 事 啦 ! 」

本 港 常 見 蟒 蛇 簡 介

品 種 : 緬 甸 蟒

身 形 : 最 長 20 呎 , 重 40 多 公 斤 , 壽 命 約 20 年

分 佈 : 西 貢 、 大 埔 、 港 島 和 大 嶼 山

攻 擊 能 力 : 有 利 齒 但 無 毒 性 , 粗 壯 身 軀 可 將 獵 物 纏 絞 至 窒 息 而 死 , 再 吞 入 腹 中

資 料 來 源 : 《 蘋 果 》 資 料 室

轉載自: 蘋果日報 2008年3月4日

75 隻龜放雪櫃冬眠

整 個 雪 櫃 都 是 烏 龜, 難 道 是 龜 苓 膏 店 子 的 存 貨 ? 不 是 , 是 英 國 尼 利 太 太 ( Shirley Neely ) 為 使 飼 養 的 75 隻 烏 龜 能 順 利 冬 眠 , 於 是 清 空 家 中 雪 櫃 , 讓 牠 們 可 在 雪 櫃 冬 眠 三 周 舒 舒 服 服 地 不 吃 不 喝 不 拉 。
尼 利 太 太 說 , 大 部 份 烏 龜 都 由 機 場 海 關 充 公 得 來 , 過 去 一 直 把 牠 們 放 在 屋 外 的 盒 子 內 , 兩 周 前 見 春 天 就 快 來 臨 , 於 是 趁 氣 溫 仍 低 , 給 每 隻 烏 龜 排 便 、 洗 澡 、 磅 重 , 然 後 放 入 雪 櫃 。 由 於 烏 龜 冬 眠 時 每 分 鐘 只 呼 吸 一 次 , 所 以 她 每 天 都 打 開 雪 櫃 門 , 讓 新 鮮 空 氣 進 入 雪 櫃 內 。 一 雪 櫃 烏 龜, 並 非 人 人 都 想 像 到 , 上 周 六 便 曾 有 不 知 就 的 訪 客 , 打 開 雪 櫃 欲 拿 酒 喝 時 , 被 眼 前 滿 的 景 象 嚇 倒 。
英 國 《 每 日 郵 報 》




80斤重蟒蛇 冬眠被凍死












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