The department is not a typical bioscience major, called ecology and evolution, and includes many scientists who have traditionally been thought to be in the field in ecology and evolutionary biology. With the contact with them, Xiaobian gradually discovered that in fact, many ecologists study problems that are inseparable from programming, and will often use bioinformatics and modeling methods to solve ecological problems, and will also study ecological problems at the genetic level. In this way, ecologists are often overlooked on the WeChat platform of "Shengxinren", a WeChat platform with genomics and bioinformatics researchers as the main reading group. Therefore, Xiaobian had the idea of writing a push from the perspective of an ecological person. Of course, for many ecologists, the most important thing is to go out into the field to do experiments and collect data. This article reviews the scientific research story of a field ecologist and takes you to see the "strategy along the creek" of ecological people.
Mosquitoes are hated by humans for their bloodthirsty creatures and their notoriety as pushers of disease. However, not all mosquitoes suck the blood of humans or mammals, and many of them feed on the blood of birds, reptiles, amphibians, and even fish. Studying the host-use patterns of different species of mosquitoes is valuable in disease prevention, prediction, and ecology.
Among the many species of mosquitoes, Uranotaenia sapphirina (a blue-banded mosquito, no Chinese translation found, here in Latin, friends with knowledge are welcome to leave a message below) is a somewhat special one: this mosquito widely distributed in the eastern United States, its host has not been identified, and scientists in previous studies have used traditional methods (molecular and serologic blood meal identification). techniques) tend to be fruitless (1).
Lawrence Reeves is a postdoctoral fellow at the University of Florida. Its research areas are the biodiversity and ecology of mosquitoes. In early 2015, Reeves and his colleagues began a search for a host for Ulanoaenia sapphirina. Like their predecessors, their research did not go well. Reeves's conventional methods of extracting mosquito blood and then PCR amplification failed, and the host DNA was not amplified. The author first wonders whether Uranotaenia sapphirina is a booty to steal other species of mosquitoes. If so, the DNA contained in the blood obtained by Uranotaenia sapphirina may be susceptible to degradation due to too long time due to the fact that it is not sucked directly from the vertebrate body (1). So Reeves et al. took blood samples in the morning, often believing that the mosquitoes had just been full. Brought back to the lab for PCR amplification, however, without any banding (1).
The authors then speculate whether the PCR primers will happen to match the host (1). To this end, the authors designed multiple PCR amplifications of primers, but all failed. Presumably, many friends know that if they encounter such problems in the laboratory, they will be told by experienced brothers and sisters to try different experimental conditions. The authors were no exception here, adjusting magnesium ions, DNA concentrations, and annealing temperatures to no avail. So the authors made a fourth guess, whether it was because the host itself had something interfering with the PCR. If this is the case, then everything should not be P out. This time, however, the author gets the strip (1).
Reeves must have been very upset at this point. But in the end he didn't give up, and he finally decided to try his luck in the wild, the mosquito's habitat: if the character outbreak happened to meet a mosquito sucking blood by a stream, he would know directly who its host was (I figured that if the lab work wasn't going to tell me anything, I'd try my luck with field observation) (1).
Friends who know Greek mythology may know that there is a legendary River Styx (transliterated as the Styx River). In fact, the Styx River really exists. It is the destination of Reeves' "Raiders along the Creek", about half an hour's drive from the University of Florida, where Reeves is located.
On the left is the location of Florida in the United States, and on the right is the university of Florida to the Stix River driving route map
On the night of September 12, 2015, the author drove to the Styx River, hoping to try his luck in such a somewhat "helpless" way (1).
Caves of the Styx River. Image from Wiki
Such a wild trip is not easy. Florida is located in the southeast of the United States, and its unique geographical location and climatic conditions have created a harsh environment of high heat and humidity and overgrown overgrown in the Styx River, and also seriously restricted the play of ecological people's housekeeping skills - "eight steps to catch cicadas". The Styx River is not only a settlement of Uranotaenia sapphirina, but also a habitat for a variety of mosquitoes and creatures such as water-bellied snakes and crocodiles. Since mosquitoes are nocturnal animals, this time out of the wilderness also needs to work at night. In short, in such a difficult environment to carry out scientific investigation, in addition to full courage and patience, it is also necessary to always raise a hundred times the spirit. To avoid missing out on moments due to drowsiness, Reeves drank double espresso (double serving espresso) before leaving (1).
As it turned out, Reeves was overly concerned. Reeves searched carefully along the stream and did not take much time to find the target object, Uranoaenia sapphirina. He quickly used a macro lens to capture almost 20 photographs (1). Strange phenomena appeared, and Reeves was keenly aware of the female mosquitoes standing on certain link animals in the photo, and appearing as if their proboscises were in contact with the animal. To his surprise, however, Reeves' rigorous and skeptical approach to science as a good ecologist made him quickly realize that it should be just a coincidence (1).
This time, Reeves was wrong again. After continuing to take and carefully studying the numerous photographs, Reeves began to believe that everything he saw was by no means a coincidence: he clearly saw a large number of mosquitoes enjoying a feast of animals such as earthworms or earthworms in the mud. The truth gradually surfaced, and Reeves finally dawned on it. It turned out that the reason for the failure of pcR host DNA was that the primers traditionally used to amplify the DNA in the blood of mosquito hosts were templated by vertebrates, and these templates were likely to be helpless to invertebrates such as link animals. This major discovery thrilled Reeves. Excited, Reeves made several phone calls, presumably to report the exciting news (Satisfied, I made a few excited phone calls from the bridge that crosses the River Styx) (1).
Feeding mosquitoes; Figure 2 in (2).
To further validate his point, back in the lab, Reeves designed specific primers for link animals (note that mosquitoes of the same invertebrate genus are also avoided). They went on to find that the DNA contained in the blood that Ulanoaenia sapphirina smoked came entirely from the animals. At this point, the secret of Uranotaenia sapphirina's blood sucking has finally been revealed. The study demonstrated for the first time that mosquitoes can host a specific link animal (we provide the first evidence, to our knowledge, that a mosquito, Uranotaenia sapphirina, specializes on annelid hosts (earthworms and leeches)), It tells us that mosquitoes can have a wider range of hosts and vary between closely related species (2). Reeves and collaborators wrote a paper on the hard-won discovery, which was published last month in Nature's magazine Commons Biology. Reeves also wrote a blog post about his research history in the nature research ecology and evolution community, which is citation 1 in this push.
In the paper, the authors further relate to the evolutionary history of mosquito blood-sucking. As we all know, most of the mosquitoes that live are based on the blood of mammals or birds. However, fossil evidence suggests that the ancestors of mosquitoes lived on Earth 30-40 million years before the origin of birds and mammals. That is to say, the act of mosquitoes sucking the blood of mammals and birds is obviously derived later. 100 million years or even earlier, the ancestors of mosquitoes should have chosen other organisms as a source of blood (2).
The evolutionary course of Culicomorpha and its relationship to the host; Figure 3 in (2).
The previous view was that the ancestors of mosquitoes may have sucked the blood of other insects. This has also been found in individual species of mosquitoes (see (2) and the citation therein for more details). The authors note that the insect's circulatory system is open, unlike vertebrates. The circulatory system of the link animal is exactly a closed cycle, that is, similar to the modern host of mosquitoes, and the immune system and hemostasis mechanism of the link animal are simpler. The authors speculate that this way of living by feeding on the blood of the animals may represent a transitional stage for mosquitoes from drinking insect blood to drinking vertebrate blood, and then slowly sharpening a sharper "sword sheath" in the long evolutionary process, and finally breaking through the tight defenses of vertebrates (2). Of course, the author said in the article that the survival mode of the Uranotaenia sapphirina sucking link animal is not necessarily a direct inheritance of the mosquito's most ancestral state, but may be transformed by its close relative species sucking frog blood. But in any case, the interaction between mosquito ancestors and animals is still a very tempting conjecture. The author discusses this in detail in the article, and interested readers should refer to the original article (2).
From a blood-sucking question to a playful exploration process, this article can really be described as a twist and turn. So, when your lab work isn't working, you might as well be like Reeves and go out and see the outside world.
citation
1.Reeves L. At the River Styx, mosquitoes feed on worm blood. 2018.
2.Reeves LE, Holderman CJ, Blosser EM, Gillett-Kaufman JL, Kawahara AY, Kaufman PE, et al. Identification of Uranotaenia sapphirina as a specialist of annelids broadens known mosquito host use patterns. Communications Biology. 2018;1(1):92.
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