Puberty Clock

Like humans, insects go through puberty. The process is known as metamorphosis. Examples include caterpillars turning into butterflies and maggots turning into flies.

But, it has been a long-standing mystery as to what internal mechanisms control how insects go through metamorphosis and why it is irreversible.

Now, a team of scientists, led by an assistant professor at the University of California, Riverside, has solved the mystery. They also believe the findings, which were published in the journal PLOS Genetics, could be applied to mammals, including humans.

Using the model organism fruit flies, the researchers found that the amount of DNA in the fruit fly controls the initial production of steroid hormones, which signal the start of metamorphosis.

More specifically, the cells that produce steroid hormones keep duplicating their DNA without cell division, making their nuclei huge. The team found that this amount of DNA in steroid hormone-producing cells is a critical indicator of their juvenile development, and it even determines when the insects get into metamorphosis.

Naoki Yamanaka, an assistant professor of entomology at UC Riverside, likened the accumulation of DNA to rings found inside trees that are used to date trees.

“The amount of DNA is like an internal timer for insect development,” Yamanaka said. “It tells the insect, ‘OK, I will grow up now.'”

Their finding explains, for the first time, why insect metamorphosis, just like human puberty, is an irreversible process. It is irreversible since DNA duplication cannot be reversed in cells. Once the cells increase the amount of DNA and start producing steroid hormones, that is the point of no return; they cannot go back to their childhood.

The findings could have multiple applications. In the short term, they could be used to help control agricultural pests by manipulating their steroid signaling pathways. They could also be used to aid beneficial insects, such as bees.

In the long term, the findings could also be used to develop better ways to treat diseases in humans related to sexual maturation, since human puberty is also controlled by steroid hormones, just like insects. The results may also aide future studies on steroid-related diseases such as breast cancer, prostate cancer, and menopause-related symptoms.

Yamanaka will continue this research by focusing on other insects, such as bumblebees and mosquitos, to see if they have a similar internal timer.

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Andean Bears

A recent wildlife survey led by SERNANP (Servicio Nacional de Áreas Naturales Protegidas por el Estado) and WCS (Wildlife Conservation Society) in the Historic Sanctuary of Machu Picchu in Peru has confirmed that the world-famous site is also home to a biologically important and iconic species: the Andean bear (Tremarctos ornatus).

Funded by the Andean Bear Conservation Alliance, the U.S. Agency for International Development, and the Gordon and Betty Moore Foundation, the year-long survey revealed the presence of Andean bears in more than 95 percent of the 368-square-kilometer study area, which includes the famous Incan ruins of Machu Picchu, one of the most visited places in South America. While it was previously known that Andean bears existed in the sanctuary, the new survey’s findings reveal a much wider presence of bears throughout the protected area.

The Historic Sanctuary of Machu Picchu is classified as a World Heritage site by UNESCO (the United Nations Educational, Scientific, and Cultural Organization) and is one of only 35 sites worldwide listed as a mixed natural and cultural site. The findings from this survey are critical for establishing a baseline for future assessments and to plan for the long-term conservation of Andean bears both within and beyond the sanctuary.

“It is amazing that this world famous location is also important habitat for Andean bears,” said Dr. Isaac Goldstein, Coordinator of WCS’s Andean Bear Program. “The results of the survey will help us to understand the needs of this species and how to manage Andean bears in this location.”

With a range stretching from Venezuela to Bolivia, the Andean bear inhabits the mist-shrouded montane forests and upland grasslands of the Andes Mountains and is South America’s only native bear species. The Andean bear is sometimes called the spectacled bear due to yellowish or white patches that surround its eyes. The species features prominently in the cultural fabric of the region, yet much is still unknown about the behaviour and ecology of the Andean bear.

The survey results also show that the Andean bears of Machu Picchu are not an isolated population, but part of a much larger population connected by montane grasslands that occur over an elevation of 3,400 meters (more than 11,000 feet above sea level). Understanding this connectivity will help wildlife managers to maintain the corridors needed for healthy bear populations. The survey itself is part of a larger effort by SERNANP and its partners to monitor Andean bears across the Machupicchu-Choquequirao Landscape, a large mountainous region containing both archeological sites and natural areas.

Fieldwork to collect data on the presence of Andean bears in the Historic Sanctuary of Machu Picchu was conducted between August 2014 and September 2015. A team of more than 30 trained researchers and park officials looked for signs of bears in a variety of habitats in the Machu Picchu protected area, ranging from Andean rainforest to montane grasslands. The study area was divided into sections 16 square kilometres in size (more than 6 square miles, the typical size of a female Andean bear’s range) to evaluate the bear’s presence in the protected area. Researchers looked for bear activity such as scat, footprints, and signs of feeding on terrestrial bromeliads (plants native to tropical and subtropical regions) along 166 kilometers (more than 100 miles) of transects throughout the sanctuary.

In addition to finding signs of bears in most of the sanctuary, the research team also determined that the presence of cattle is a potential risk to Andean bears in the sanctuary. The survey results will help inform the effective management of the Historic Sanctuary of Machu Picchu, the most visited protected area in Peru.

WCS has contributed to extensive research on the ecological needs of the Andean bear throughout its range. In 2014, WCS published the document “Andean Bear Priority Conservation Units in Bolivia and Peru” that consolidated information from 25 Andean bear experts on the distribution of the species and recommendations for conservation. In the U.S., WCS’s Queens Zoo is home to the only Andean bear exhibit in New York City. Queens Zoo Director and Curator Scott Silver serves as Coordinator for the Andean Bear Species Survival Plan (SSP), a cooperative breeding program administered by the Association of Zoos and Aquariums that ensures genetic variability within accredited zoo populations.

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Domestic Cats

DNA found at archaeological sites reveals that the origins of our domestic cat are in the Near East and ancient Egypt. Cats were domesticated by the first farmers some 10,000 years ago. They later spread across Europe and other parts of the world via the trade hub of Egypt. The DNA analysis also revealed that most of these ancient cats had stripes: spotted cats were uncommon until the Middle Ages.

Five subspecies of the wildcat Felis silvestris are known today. All skeletons look exactly alike and are indistinguishable from that of our domestic cat. As a result, it’s impossible to see with the naked eye which of these subspecies was domesticated in a distant past. Paleogeneticist Claudio Ottoni and his colleagues from KU Leuven (University of Leuven) and the Royal Belgian Institute of Natural Sciences set out to look for the answer in the genetic code. They used the DNA from bones, teeth, skin, and hair of over 200 cats found at archaeological sites in the Near East, Africa, and Europe. These remains were between 100 and 9,000 years old.

The DNA analysis revealed that all domesticated cats descend from the African wildcat or Felis silvestris lybica, a wildcat subspecies found in North Africa and the Near East. Cats were domesticated some 10,000 years ago by the first farmers in the Near East. The first agricultural settlements probably attracted wildcats because they were rife with rodents. The farmers welcomed the wildcats as they kept the stocks of cereal grain free from vermin. Over time, man and animal grew closer, and selection based on behaviour eventually led to the domestication of the wildcat.

Migrating farmers took the domesticated cat with them. At a later stage, the cats also spread across Europe and elsewhere via trade hub Egypt. Used to fight vermin on Egyptian trade ships, the cats travelled to large parts of South West Asia, Africa, and Europe. Bones of cats with an Egyptian signature have even been found at Viking sites near the Baltic Sea.

“It’s still unclear, however, whether the Egyptian domestic cat descends from cats imported from the Near East or whether a separate, second domestication took place in Egypt,” says researcher Claudio Ottoni. “Further research will have to show.” The scientists were also able to determine the coat pattern based on the DNA of the old cat bones and mummies. They found that the striped cat was much more common in ancient times. This is also illustrated by Egyptian murals: they always depict striped cats. The blotched pattern did not become common until the Middle Ages.

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See also; Domestic Mice.


 

Domestic Mice

Long before the advent of agriculture, hunter-gatherers began putting down roots in the Middle East, building more permanent homes and altering the ecological balance in ways that allowed the common house mouse to flourish, new research in the Proceedings of the National Academy of Sciences indicates.

“The research provides the first evidence that, as early as 15,000 years ago, humans were living in one place long enough to impact local animal communities, resulting in the dominant presence of house mice,” said Fiona Marshall, study co-author and a professor of anthropology at Washington University in St. Louis. “It’s clear that the permanent occupation of these settlements had far-reaching consequences for local ecologies, animal domestication and human societies.”

Marshall, a noted expert on animal domestication, considers the research exciting because it shows that settled hunter-gatherers rather than farmers were the first people to transform environmental relations with small mammals. By providing stable access to human shelter and food, hunter-gatherers led house mice down the path to commensalism, an early phase of domestication in which a species learns how to benefit from human interaction.

The findings have broad implications for the processes that led to animal domestication.

“The findings provide clear evidence that the ways humans have shaped the natural world are tied to varying levels of human mobility,” said Marshall, the James W. and Jean L. Davis Professor in Arts & Sciences. “They suggest that the roots of animal domestication go back to human sedentism thousands of years prior to what has long been considered the dawn of agriculture.”

Led by Thomas Cucchi of National Center for Scientific Research in Paris, France, and Lior Weissbrod of the University of Haifa in Israel, the study set out to explain large swings in the ratio of house mice to wild mice populations found during excavations of different prehistoric periods at an ancient Natufian hunter-gatherer site in the Jordan Valley of Israel.

Examining tiny species-related variations in the molar shapes of fossilized mice teeth dating back as far as 200,000 years, the team built a timeline showing how the populations of different mice fluctuated at the Natufian site during periods of varying human mobility.

The analysis revealed that human mobility influenced competitive relationships between two species of mice; the house mouse (Mus musculus domesticus)and a short-tailed field mouse (M. macedonicus), that continue to live in and around modern settlements in Israel. These relationships are analogous to those of another pair of species called spiny mice which Weissbrod and Marshall discovered among semi-nomadic Maasai herders in southern Kenya.

Findings indicate that house mice began embedding themselves in the Jordan Valley homes of Natufian hunter-gatherers about 15,000 years ago, and that their populations rose and fell based on how often these communities picked up and moved to new locations.

When humans stayed in the same places for long runs of time, house mice out-competed their country cousins to the point of pushing most of them outside the settlement. In periods where drought, food shortages or other conditions forced hunter-gatherers to relocate more often, the populations of house mice and field mice reached a balance similar to that found among modern Maasai herders with similar mobility patterns.

The study confirms that house mice were already a fixture in the domiciles of eastern Mediterranean hunter-gatherer villages more than 3,000 years before the earliest known evidence for sedentary agriculture.

It suggests that the early hunter-gatherer settlements transformed ecological interactions and food webs, allowing house mice that benefited from human settlements to out-compete wild mice and establish themselves as the dominant population.

“The competition between commensal house mice and other wild mice continued to fluctuate as humans became more mobile in arid periods and more sedentary at other times, indicating the sensitivity of local environments to degrees of human mobility and the complexity of human environmental relationships going back in the Pleistocene,” said Weissbrod, currently a research fellow at the Zinman Institute of Archaeology at the University of Haifa.

Weissbrod’s research involves analysis of microvertebrate remains from a wide range of prehistoric and historic sites in Israel and the Caucasus dealing with paleoecology and human-ecosystem interactions.

A 2010 graduate of the doctoral program in archaeological anthropology at Washington University, he began research for this study as part of a dissertation examining fluctuations in populations of mice and other small animals living around Maasai cattle herding settlements in Kenya.

Marshall helped Weissbrod to develop the ethnographic context for underlying research questions about the ecological impact of human mobility. Together they built field-based ecological frameworks for understanding changing animal human interactions through time focusing on mice and donkeys.

Working from his lab in Paris, Cucchi used a new technique called geometric morphometrics to identify the mouse fossils and reliably distinguish telltale differences in the miniscule remains of house mice and wild species. The method relies on high resolution imaging and digital analysis to categorize species-related variations in molar outlines nearly as thin as a single millimeter.

The findings, and the techniques used to document them, are important to archaeological research in a broader sense because they lend further support to the idea that fluctuations in ancient mouse populations can be used as a proxy for tracking ancient shifts in human mobility, lifestyle and food domestication.

“These findings suggest that hunter-gatherers of the Natufian culture, rather than later Neolithic farmers, were the first to adopt a sedentary way of life and unintentionally initiated a new type of ecological interaction; close coexistence with commensal species such as the house mouse,” Weissbrod said. “The human dynamic of shifts between mobile and sedentary existence was unraveled in unprecedented detail in the record of fluctuations in proportions of the two species through time.”

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See also; Domestic Cats.


 

Dairy Camel

A growing number of wild camels from central Australia are being turned into dairy cows, as interest in the camel milk industry builds.
The number of dairies has now risen to around 10 and more products are starting to appear on the market including fresh pasteurised camels’ milk, cheese, ice-cream, yoghurt, camel milk powder and skincare.

Dairy Camel
Chris Williams and his wife Megan are former dairy cattle farmers, who first encountered camels when they worked on a beef property in the outback, where the humped animals were seen as pests.
But when they decided to set up their own business at Kyabram in Victoria, Mr Williams said they “wanted something niche”, and gave camels a second look.

“We researched many different things… milking goats, buffalo, even miniature Herefords at one stage and then we heard you can milk camels,” he said.
The high retail price was also a drawcard.
Pasteurised camel milk sells for more than $20 per litre in some states.
Farmers say camel milk is expensive because the production costs are high and the yields are much lower than what dairy cattle produce.
“We couldn’t have budgeted for how much it was going to cost to just get a litre of milk from a camel, having been no major research or industry,” Ms Williams said.
“Even just last year, cost of production was up around $17 per litre just to produce it.”
One producer who is diversifying into new products is Lauren Brisbane who owns QCamel in the Sunshine Coast Hinterland.
“We have a real opportunity to develop this industry and be able to supply milk around the world if we all work together,” she said.
Ms Brisbane has been working with camels for 12 years and decided to start milking them a few years ago.
“I’m really passionate about them. They’re so intelligent, that’s what I love,” she said.
But she also warns it is a risky industry not a cash cow.
“If people are coming, looking at it and going oh we’re going to make all this money then don’t bother,” she said.
“There’s nothing quick about a camel, it takes time.”

That isn’t stopping a growing number of local and international companies from investing.
It’s understood Chinese investors are looking at setting up a camel milk business in South Australia.
And investors from the United Arab Emirates have already funded Camilk’s $8 million pilot farm at Rochester, north of Melbourne.
Then there’s The Australian Wild Camel Corporation at Harrisville, south-west of Brisbane, which has the country’s largest herd of 450 animals including 65 milkers.
The company, which is being funded by local investors, aims to build the milking herd to 1,000 over the next few years.
“Our main issue is to take it from that cottage industry,” chief operating officer Paul Martin said.
“We’ve got to jump that hurdle and get it into a commercial where we can sell the produce overseas on volume and start to get our efficiencies on farm.”
Like other farmers, Mr Martin is trying to get the public to see camels in a new light by producing cheese, ice-cream and skincare.
“In a land like Australia we’ve got this animal that can survive through pretty well anything mother nature can throw at it and we’re shooting it,” he said.
“And yet it produces meat, it produces milk, it produces fat products, hide leather. It’s an amazing animal.”

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Milk

New knowledge on milk composition and quality is of essential importance to consumers as well as the industry. There are therefore considerable research efforts in milk worldwide. One of the major topics, concerns milk’s content of different proteins and their importance to human health. Basically, milk consists of two protein types, whey and casein. Casein can be further divided into four categories. One of these, beta casein, attracts particular attention. Several beta casein types exist and A1 and A2 are the most common.

It has been suggested that A2-protein milk is a healthier alternative to A1-protein milk, as the latter is claimed to metabolise into potentially detrimental peptides in the intestine. One specific peptide formed during digestion is further claimed to have unfavourable effects on the consumers drinking it. However, the European Food Safety Authority (EFSA) dismissed these claims in 2009 as undocumented.

It is currently debated whether some of the discomfort reported by some milk consumers regarding impact on the gastrointestinal system may be caused by discomfort originating from these detrimental peptides. A2-milk has been labelled a more “original” milk and is closer to breast milk. Foreign companies have succeeded in establishing specialised industries that sell milk that only contains A2-type beta casein. In December 2016, the Danish dairy Thise, introduced a Danish variant.

 

This particular area still requires additional research and there is no scientific evidence to substantiate that one protein type is superior compared to the other, states Professor Lotte Bach Larsen, Department of Food Science at Aarhus University:

“ I acknowledge that further research and examination is required within this particular area in order to base the debate on solid, fact-based argumentation. We cannot rule out that some consumers, who feel discomfort when consuming milk, might benefit from drinking solely A2-milk.”

In a recently finished investigation, Lotte Bach Larsen and her colleagues from the Department of Food Science cooperated with Norwegian scientists to examine if the two different protein types give rise to different metabolisation patterns and thus the formation of potentially bioactive protein fragments. In their examination the scientists used gastric and intestinal juices from humans to study how enzymes in the gastrointestinal tract break down the proteins. The experiment was accomplished in a laboratory model system and using protein types that were purified from milk from cows whose milk contained either solely A1 or A2 variants of the protein.

“The examination demonstrates quite as expected, that a number of different peptides are formed from both protein types, when the milk is metabolised. But, it also turns out that the peptide in question is actually present when both A1 and A2 milk is digested. However, the content of this specific peptide formed from A1 beta casein protein variant by the human digestion enzymes was approx. three times higher than liberated from the A2 beta casein variant. As this study was carried out with purified beta casein variants, there is a need to examine whether there is a difference in content of this specific peptide, if digestion is going on using milk and not simply isolated beta casein proteins. In addition, it would be beneficial to carry out a proper human intervention study on the eventual effects when consuming the two different types of milk, and also examine if the peptide can be measured in the blood” says Lotte Bach Larsen.

 

Another interesting aspect when discussing the difference between A1 and A2 milk is the fact that milk containing the A2-type beta casein is actually the most frequent type in Danish dairy cattle. Scientists from the Department of Food Science were able to conclude this fact when they, in connection with a major research project, carried out a screening of the protein composition of Danish milk. Actually, the frequency of the A2 protein was almost the same in both Danish Jersey cattle and Danish Holstein cattle.

“It is rather interesting if consumers consider A2 milk to be something unique and special. We should point out that even though most of the Danish milk is mixed, dairy milk will normally contain both types, but with levels of the A2 type over the A1 type, as it seems that A2 is present in highest frequency over the A1 variant. If you choose a milk type that specifically contains the A2 protein of the beta casein, you should know that this milk comes from cows that have been screened for the variants and selected for this production” says Lotte Bach Larsen.

She hopes that the future will bring an increased focus on studies in the metabolism of milk proteins in human studies.

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A Matter Of Scale

A Fishy Defence.

While many lizards can drop their tails when grabbed, fish-scale geckos in the genus Geckolepis have large scales that tear away with ease, leaving them free to escape whilst the predator is left with a mouth full of scales. Scientists have now described a new species (Geckolepis megalepis) that is the master of this art, possessing the largest scales of any gecko.

The skin of fish-scale geckos is specially adapted to tearing. The large scales are attached only by a relatively narrow region that tears with ease, and beneath them they have a pre-formed splitting zone within the skin itself. Together, these features make them especially good at escaping from predators. Although several other geckos are able to lose their skin like this if they are grasped really firmly, Geckolepis are apparently able to do it actively and at the slightest touch. And while others might take a long time to regenerate their scales, fish-scale geckos can grow them back, scar-free, in a matter of weeks.

This remarkable ability has made these geckos a serious challenge to the scientists who want to study them. Early researchers described how it was necessary to catch them with bundles of cotton wool, to avoid them losing almost all of their skin. Today, little has changed and researchers try to catch them without touching them if possible, by luring them into plastic bags. But once they are caught, the challenges are not over; identifying and describing them is even harder.

“A study a few years ago showed that our understanding of the diversity of fish-scale geckos was totally inadequate,” says Mark D. Scherz, lead author of the new study and PhD student at the Ludwig Maximilian University of Munich and Zoologische Staatssammlung München, “it showed us that there were actually about thirteen highly distinct genetic lineages in this genus, and not just the three or four species we thought existed. One of the divergent lineages they identified was immediately obvious as a new species, because it had such massive scales. But to name it, we had to find additional reliable characteristics that distinguish it from the other species.” A challenging task indeed: one of the main ways reptile species can be told apart is by their scale patterns, but these geckos lose their scales with such ease that the patterns are often lost by the time they reach adulthood. “You have to think a bit outside the box with Geckolepis. They’re a nightmare to identify. So we turned to micro-CT to get at their skeletons and search there for identifying features.” Micro-CT (micro-computed tomography) is essentially a 3D x-ray of an object. This method is allowing morphologists like Scherz to examine the skeletons of animals without having to dissect them, opening up new approaches to quickly study the internal morphology of animals.

By looking at the skeletons of the geckos, the team was able to identify some features of the skull that distinguish their new species from all others. But they also found some surprises; a species named 150 years ago, Geckolepis maculata, was confirmed to be different from the genetic lineage that it had been thought to be. “This is just typical of Geckolepis. You think you have them sorted out, but then you get a result that turns your hypothesis on its head. We still have no idea what Geckolepis maculata really is, we are just getting more and more certain what it’s not.”

The new species, Geckolepis megalepis, which was described by researchers from the US, Germany, and Columbia in a paper published in the open access journal PeerJ, is most remarkable because of its huge scales, which are by far the largest of any gecko. The researchers hypothesize that the larger scales tear more easily than smaller scales, because of their greater surface area relative to the attachment area and larger friction surface. “What’s really remarkable though is that these scales, which are really dense and may even be bony and must be quite energetically costly to produce and the skin beneath them tear away with such ease and can be regenerated quickly and without a scar,” says Scherz. The mechanism for regeneration, which is not well understood, could potentially have applications in human medicine, where regeneration research is already being informed by studies on salamander limbs and lizard tails.

Fish scale gecko

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