麋鹿沧桑命运与未来保护展望

麋鹿作为中国特有的鹿科动物,经历129年的保护努力,种群数量恢复到10000多头。因近亲繁殖严重,表面上看已无灭绝危险,但仍存在巨大隐忧。通过对麋鹿种群变迁、灭绝、重引入、恢复现状及四大种群(乌邦寺、南海子、大丰、石首野化种群)的发展趋势进行追踪分析,探究近千年来困扰麋鹿种群发展壮大的多重因素,提出种群保护与栖息地保护并重、强化疫病监测等保护对策,为麋鹿及其它大型陆生濒危哺乳动物突破种群发展瓶颈提供借鉴。     

Do Père David's Deer Lose Memories of Their Ancestral Predators?

Whether prey retains antipredator behavior after a long period of predator relaxation is an important question in predator-prey evolution. Père David''s deer have been raised in enclosures for more than 1200 years and this isolation provides an opportunity to study whether Père David''s deer still respond to the cues of their ancestral predators or to novel predators. We played back the sounds of crows (familiar sound) and domestic dogs (familiar non-predators), of tigers and wolves (ancestral predators), and of lions (potential naïve predator) to Père David''s deer in paddocks, and blank sounds to the control group, and videoed the behavior of the deer during the experiment. We also showed life-size photo models of dog, leopard, bear, tiger, wolf, and lion to the deer and video taped their responses after seeing these models. Père David''s deer stared at and approached the hidden loudspeaker when they heard the roars of tiger or lion. The deer listened to tiger roars longer, approached to tiger roars more and spent more time staring at the tiger model. The stags were also found to forage less in the trials of tiger roars than that of other sound playbacks. Additionally, it took longer for the deer to restore their normal behavior after they heard tiger roars, which was longer than that after the trial of other sound playbacks. Moreover, the deer were only found to walk away after hearing the sounds of tiger and wolf. Therefore, the tiger was probably the main predator for Père David''s deer in ancient time. Our study implies that Père David''s deer still retain the memories of the acoustic and visual cues of their ancestral predators in spite of the long term isolation from natural habitat.     

Albert Gaudry et l'émergence de la paléontologie darwinienne au xixe siècle

In this paper, paleontologists who, after the publication of “On the Origin of Species”, applied Darwin's research program on genealogy, are labeled Darwinians, not only evolutionists. A special attention is given to two paleontologists, Albert Gaudry and Gaston de Saporta. New data included in this article are Gaudry's notes written on his copy of “De l'origine des espèces” published in French in 1862. If one tries to grasp the impact of Darwin's work in the XIXth century, contrary to the common attitude, the defense of natural selection as the driven concept of evolution is not considered to be crucial. Later, Charles Depéret synthesized the growing knowledge of the second part of the XIX^th century but did not appear to be more Darwinian than his forerunners. From Darwin's writings it is concluded that the reference to biological progress inherent to Gaudry's and Saporta's works does not radically exclude these authors from the Darwinian realm.     

Evidence of effects of human disturbance on alert response in Père David's deer (Elaphurus davidianus)

To understand effects of human disturbance on alert response of Père David's deer, we carried out an experiment in the Dafeng Père David's Deer Reserve (32°59′–33°03′N, 120°47′–120°53′E), China. In the spring and summer, we observed alert responses (including stare, walking away, and flee) of deer and recorded the intensity of tourist disturbance in a small display pen using a laser‐range finder to measure the alert distance of a free‐ranging group in a large enclosure. We also recorded the pattern of head orientation when deer were resting in these two deer groups. After statistical analysis, we found that: 1) in small pen, the frequency of alert response was significantly different among different intensities of human disturbance; strong disturbance resulted in higher frequency of alert response; 2) stare distance in the free‐ranging group in summer was significantly longer than that in spring, but the distance of walking away and the distance of flee showed no significant difference between the two seasons; and 3) in free‐ranging group, there was no significant directional difference in head orientation, whereas in display group, there was a significant directional difference in head orientation. We suggest that: 1) under the captive situation, human disturbance may be one of the factors that affect alert response in Père David's deer; and 2) Père David's deer adopted different alert response to adapt to human disturbance under different circumstance. We recommended that relationships between alert response and human disturbance should be considered in ex situ conservation of this field extinct deer. Zoo Biol 26:461–470, 2007. © 2007 Wiley‐Liss, Inc.     

湿地自然保护区旅游者环境教育感知研究——以盐城丹顶鹤、麋鹿国家自然保护区为例

环境教育是当前生态旅游研究中的热点论题。基于生态旅游动机、环境教育途径、环境教育感知及环境教育效果4个结构变量,以生态旅游发展处于起步阶段的盐城丹顶鹤保护区和处于稳定发展阶段的盐城麋鹿保护区为例,构建湿地自然保护区旅游者环境教育感知影响结构关系模型,深入分析不同生命周期阶段生态旅游地旅游者环境教育感知分异及其影响因素。结果表明:(1)生态旅游动机、环境教育途径、环境教育感知均对环境教育效果产生正向影响。丹顶鹤保护区生态旅游动机对环境教育效果产生显著正向影响,环境教育途径、环境教育感知对环境教育效果均产生正向影响;麋鹿保护区生态旅游动机、环境教育途径均对环境教育效果产生正向影响,环境教育感知对环境教育效果产生显著正向影响。(2)在生态旅游动机、环境教育途径、环境教育感知3个分维度上,丹顶鹤保护区分别以一般生态旅游动机、常规环境教育途径、表层环境教育感知为主,麋鹿保护区则分别以严格生态旅游动机、专门环境教育途径、深度环境教育感知为主。(3)不同生命周期阶段生态旅游地游客环境教育效果存在差异。丹顶鹤保护区游客环境教育效果主要集中在态度、行为效果上,意识效果为辅,知识、技能效果作用较小;麋鹿保护区游客环境教育效果则以知识、态度效果为主,行为、技能、意识效果均起辅助作用。     

Diet composition and selection of Père David's deer in Hubei Shishou Milu National Nature Reserve,China

Hubei Shishou Milu National Nature Reserve is an ideal place to restore the wild population of Père David's deer (Elaphurus davidianus). Understanding foraging ecology and diet composition is essential for assessing population development or establishing long-term effective conservation measures for endangered species. However, little is known about the diet composition of Père David's deer and its diet selection mechanism. In this study, we used stable isotope technology to investigate the diet composition of Père David's deer according to various tissues (i.e., fur, muscle, liver, heart, and feces) and seasons, and evaluated the correlation between the nutrient composition of plants and diet composition. Bayesian isotope analysis showed that the autumn and winter diet estimated by fur and fecal samples indicated a diet dominated by C₃ grasses (42.7%–57.2%, mean), while the summer diet estimated by muscle and liver samples was dominated by C₃ forbs (30.9%–41.6%, mean). The Pearson correlation test indicated that the contribution of winter diet composition reflected by fur and fecal samples was associated with correlations with crude protein (r = .666, p < .01) and soluble sugars (r = .695, p < .01). The results indicated that crude protein and soluble sugars were important factors influencing the winter diet selection of Père David's deer. In the context of the current reintroduction facing many challenges, such as habitat fragmentation, wetland degradation, and human disturbance, comprehensively evaluating the diet selection mechanism of Père David's deer under different resource specificities and temporal changes should be considered in the future.     

Motivated research

While Europe is locked in the debate about basic versus applied research, Louis Pasteur solved the problem more than 100 years ago. Antoine Danchin comments on Pasteur''s notion of ‘motivated research'' and how it leads both to new discoveries and to new applications.Three years ago, a senior politician attended his country''s Annual Congress for the Advancement of Science to give the introductory lecture. He asked the attending scientists to make science and research more attractive to young students and the general public, and asked his countrymen to support scientists to address the urgent challenges of global climate change, energy needs and dwindling water resources. It was neither a European nor a US politician, but the Indian Prime Minister Manmohan Singh who made this speech about the relationship between research and its practical applications. This is such an important topic that one might think it deserves appropriate attention in Europe, yet we fail to address it properly. Instead, we just discuss how science should serve society or contribute to the ‘knowledge-based economy'', or how ‘basic'' or ‘fundamental'' research is opposed to ‘applied'' or ‘industrial'' research and how funding for ‘big science'' comes at the expense of ‘little academic'' research.This dichotomy between the research to generate knowledge and the application of that knowledge to benefit humankind seems to be a recent development. In fact, more than 100 years ago Louis Pasteur avoided this debate altogether: one of his major, yet forgotten, contributions to science was the insight that research and its applications are not opposed, but orthogonal to each other (Stokes, 1997). If Niels Bohr ‘invented'' basic academic research—which was nevertheless the basis for many technological inventions and industrial applications—Pasteur developed what we might call ‘motivated'' research.How is research motivated and by what? By definition, scientists are citizens and members of the general public and, like the public, they are motivated by two forces: on the one hand, in Rudyard Kipling''s words, “man''s insatiable curiosity”; on the other hand, a desire for maintaining and improving their well-being. These are not contradictory to one another; curiosity nourishes dreams of a brighter future and leads to discoveries that contribute to well-being.Pasteur understood that it is essential to take account of society''s demands and desires; that science must be motivated by what people want. Still, there are severe misgivings about the nature of research. These stem from the mistaken but popular assumption that the scientists'' main task is to find solutions to current problems or to fulfil our desires. Problems and desires, however, are not enough, because finding solutions also requires creativity and discovery, which, by their very nature, are unpredictable. Often we do not even know what we need or desire and it is only through curiosity and more knowledge that we find new ways to improve our well-being. Motivation by itself is, therefore, not enough to lead to discovery. Motivation simply helps us choose between many different goals and an infinite number of paths to gain novel knowledge. Subsequently, each path, once chosen, must be explored using the scientific method, which is the only way to new discoveries.Motivation helps us to ask relevant questions. For example, why do wine and beer go sour without any apparent reason? Pasteur set out to design experiments that showed that fermentation is caused by microorganisms. A few years later, silkworms were suddenly dying of a terrible disease in the silk factories of southern France. The French government called on Pasteur for help, who eventually found that a parasite had infected silkworm eggs and proposed solutions to eradicate the disease. The original question therefore led to germ theory and bacteriology, helped to develop solutions to infectious diseases, and eventually created the whole field of microbiology.Motivation leads to conceptual and experimental research, which generates discoveries and new technologies. Discoveries, in turn, are the basic resource for the creation of general knowledge and the development of new products, services and other goods that fulfil public demands and generate jobs. The study of the ‘diseases'' of beer and wine also led to the development of fermentation processes that are still in use today. The same motivation that drove Pasteur in the nineteenth century now enables us to tackle current problems, such as pollution, by studying microbial communities that make compost or thrive in garbage dumps. Motivated research therefore reconciles our curiosity with the creation of knowledge and enables us to address pressing needs for humanity.Because it is strongly inspired by—even rooted in—society''s demands and desires, motivated research also raises accompanying ethical, legal, social and safety issues that should be compelling for all research. As mentioned above, scientists are members of the public who share the same concerns and demands as their fellow citizens and therefore participate with a general, public intelligence that, too often, is absent from academic research. This absence of ‘common sense'' or societal expectations generates the misunderstandings concerning research in biology and the development of biotechnology. These misconceptions—whether about the purported risks of genetically modified organisms or the exaggerated expectations for cancer therapies—can create real suffering in society and inefficient allocation of limited resources. It is therefore advisable for researchers to listen more to the public at large in order to find the motivation for their work.     

麋鹿鹿角脱落、群主更替、产仔的年节律及其环境影响因子

本文在2014—2016年三个冬季(12月—翌年2月)收集了北京南海子麋鹿苑半散放麋鹿自然脱落的角,并观察和记录了2015—2017年发情期(5—9月)群主更替和2016—2018年产仔期(3—7月)麋鹿幼仔出生情况,结合2014—2018年年平均气温、季平均气温、月平均气温、年降雨量、雨季开始时间、种群密度等环境因子,对鹿角脱落、群主更替、产仔等繁殖特征的年节律及其环境影响因子进行了研究。结果表明：1)麋鹿鹿角脱落、群主更替、产仔的年节律均存在年际差异。2)鹿角脱落时间为12月开始,1月下旬或2月上旬结束。3)发情期为5月下旬或6月上旬开始,9月上旬结束;2015—2017年发情期时间有延长的趋势。4)产仔期为3月中旬或4月中旬开始,5月下旬或7月下旬结束。5)麋鹿鹿角脱落、群主更替、产仔的年节律存在明显的同步关系,其中鹿角脱落开始时间、鹿角脱落高峰期、鹿角脱落结束时间、第一次发情期开始时间、群主更替高峰期、产仔期开始时间、产仔高峰期、产仔期结束时间与前一年度比较均出现同步提前的现象。6)鹿角脱落年节律存在随着12月平均气温升高而提前的现象;产仔期开始时间和产仔高峰期存在随着前一年9月平均气温的升高而提前的现象。7)鹿角脱落年节律表现出随着年降雨量的增多而提前的现象;第一次发情期开始时间、群主更替高峰期的年节律表现出随着前一年度年降雨量的增多而提前的现象。8)麋鹿鹿角脱落、群主更替、产仔的年节律均不存在随着种群密度升高或降低而提前或延迟的现象。麋鹿繁殖特征的年节律是一个复杂的过程,受气候、营养、种群密度、纬度等环境因子的影响。     

Pater Davids Hirsch oder Milu (Elaphurus davidianus Milne Edwards, 1866), 150 Jahre, 1865 bis 2015

The population of the Père David's deer or milu (Elaphurus davidianus), which was discovered in China by Père Armand David in 1866, has grown from five, or even merely three individuals, imported from China to approximately 5000 during a time-span of 140 years. We tried to find out more about the origin of the 18 individuals which formed the original herd of the 11^th Duke of Bedford at Woburn Abbey. His breeding-group was the only safeguard for this species between the years 1900 and 1946. Of the 18 individuals three were offspring of Berlin Zoo, three originated from Cologne Zoo and probably all the rest came from the Jardin d‘Acclimatation in Paris. The origin of the breeding herd at the Jardin d‘Acclimatation is not clear. The first individuals either came from Berlin Zoo or were imported directly from China in the years between 1876 and 1886. In Berlin Zoo's breeding records there is a remarkable gap for the years 1879 and 1880. If they came from Berlin Zoo, the imported male and two females would be the sole founders of the herd, and if the Jardin d‘Acclimatation had done an own import, then there would be at least five founders. At Berlin Zoo at least 18 milu calves were born between the years 1878 and 1895. The final destinations of most of these could be traced in literature. Some of them are not quite conclusive yet. We sketched the development of the worldwide zoo-stock of Père David's deer, the return to China and the re-settlement in the original habitat in newly established reserves and finally even outside the reserves. After centuries the milu has again gained the status of a free-living species thanks to the efforts of several zoological gardens, the Dukes of Bedford and the Chinese conservation authorities.     

Zoo behaviour science in the Research Centre for Vertebrate Studies of the Academy of Sciences of the German Democratic Republic (in the Animal Park of Berlin)

This is a report of the results of behaviour science studies in the Animal Park of Berlin and the Academy of Sciences in the German Democratic Republic (G.D.R.). The major goal of this research is to investigate the behaviour of rare animals as a basis for zoological research, systematics and comparative studies in evolution. In addition, further research provided information directly applicable to behavioural management in zoos, farms and wild animal collections. Three main comparative studies dealt with urination and defecation in mammals, allelomimetic behaviour in vertebrates, and audio-visual orientation responses in several species of birds and mammals. Ethograms were created for the Red Woolly Opossum, Maned Wolf, Takin and Giant Eland Antelope. Social and reproductive behaviour studies were conducted on the Wolf, Golden Lion Marmoset, Père David's Deer, Mouflon and Wild Boar. Reports are included on the circadian activity of Pigmy Armadillo and Wild Boar. New information was revealed regarding communication in Mouflon and Père David's Deer, in addition to the new finding that some social behaviour patterns in Wild Boar are dependent on circadian rhythms. Three wolf packs studied consecutively in the same enclosure revealed that each pack differed in its social behaviour and that the dominant female (alpha female) determined the social structure. The problem of animal-human interactions is discussed. Zoos are seen as a medial stage between wilderness and farm management. It is suggested that an important task of zoo behaviour science is to study the ability of wild animals to adapt to purposes such as animal farms, animal husbandry institutes and domestic animal productivity, and to study the behaviour of the original forms of domestic animals in order to better understand and manage them.     

Incisor size and community structure in rodents: Two tests of the role of competition

We used two different approaches to test for the effect of interspecific competition on community-wide patterns in the size of the upper incisor in six rodent communities. One tests for constancy of size ratios between adjacent species (Barton and David's test), and the other tests for minimum mean size overlap between species pairs (randomization test). The results of the two tests were more congruent for the radius of the upper incisor than for its diameter. Although a number of tests gave significant results, they led to a consistent rejection of the null hypothesis of a randomly generated pattern only in two communities from an African rainforest. Many factors are likely to disturb community structure, among which we identify recent species introductions and the presence of rare species. Our results also show that Hutchinson's rule of a limiting size similarity does not hold; the mean size ratio between adjacent species was correlated with the overall size range and the number of species in a community.     

麋鹿鹿角生长周期及影响因子

2013年8月至2014年8月,使用望远镜(SWAROVSKI 8×42 WB)和照相机(Canon 550D 70×300)观察北京南海子59只雄性麋鹿茸的生长和角脱落周期,发现麋鹿角总体趋势呈随着年龄的减少,脱角日期越迟,且等级序位高或者鹿王较年老个体先脱落。收集2012年12月至2014年2月两年度麋鹿自然脱落的角,研究表明,个体而言,左右角脱角顺序差异明显,同一天脱落两角者占17.0%,左角先脱落者占34.1%,右角先脱落者占48.8%,重量重和重量轻的角先脱落的个体各占41.5%,个体成对的左右角脱落时间间隔短,平均为1.98d;群体而言,角重量与脱角时间呈显著负相关,总体呈现角重的个体角先脱落,但不是角最重的个体角第一个脱落。2013年6月至2014年5月,对北京南海子、湖北石首、江苏大丰、天津七里海、浙江慈溪、浙江临安、海南海口、河北滦河上游、辽阳千山等9个地区麋鹿种群麋鹿角脱落起止时间进行调查,研究表明野生种群脱角时间比圈养种群早;迁入热带地区海南的麋鹿仍有规律的角周期;同一栖息地不同年份角周期存在差异,不同栖息地间麋鹿角周期存在差异;脱角起始时间与海拔、经度、纬度、年平均气温、圈养情况和气候类型等影响因子不存在统计学上显著的相关性,但光周期和激素直接主导和调节着角周期,年龄大小、角重量、营养以及与营养相关的能量、种群密度、物候等环境因子均影响角周期。     

From intestine transport to enzymatic regulation: The works of the Spanish biochemist Alberto Sols (1917–1989)

In this paper the scientific trajectory of Spanish influential biochemist Alberto Sols (1917–1989) is presented in comparative perspective. His social and academic environment, his research training under the Cori's in the US in the early 1950s and his works when coming back to Spain to develop his own scientific career are described in order to present the central argument of this paper on his path from physiological research to research on enzymatic regulation. Sols' main contributions were both scientific and academic. He and his collaborators not only contributed to biological knowledge on the biochemistry of metabolic regulation but to the active reception of biochemistry in the Spanish academia and to update of Spanish medical education.     

Estimating Neospora caninum prevalence in wildlife populations using Bayesian inference

Prevalence of disease in wildlife populations, which is necessary for developing disease models and conducting epidemiologic analyses, is often understudied. Laboratory tests used to screen for diseases in wildlife populations often are validated only for domestic animals. Consequently, the use of these tests for wildlife populations may lead to inaccurate estimates of disease prevalence. We demonstrate the use of Bayesian latent class analysis (LCA) in determining the specificity and sensitivity of a competitive enzyme‐linked immunosorbent assay (cELISA; VMRD^®, Inc.) serologic test used to identify exposure to Neospora caninum (hereafter N. caninum) in three wildlife populations in southeastern Ohio, USA. True prevalence of N. caninum exposure in these populations was estimated to range from 0.1% to 3.1% in American bison (Bison bison), 51.0% to 53.8% in Père David's deer (Elaphurus davidianus), and 40.0% to 45.9% in white‐tailed deer (Odocoileus virginianus). The accuracy of the cELISA in American bison and Père David's deer was estimated to be close to the 96% sensitivity and 99% specificity reported by the manufacturer. Sensitivity in white‐tailed deer, however, ranged from 78.9% to 99.9%. Apparent prevalence of N. caninum from the test results is not equal to the true prevalence in white‐tailed deer and Père David's deer populations. Even when these species inhabit the same community, the true prevalence in the two deer populations differed from the true prevalence in the American bison population. Variances in prevalence for some species suggest differences in the epidemiology of N. caninum for these colocated populations. Bayesian LCA methods could be used as in this example to overcome some of the constraints on validating tests in wildlife species. The ability to accurately evaluate disease status and prevalence in a population improves our understanding of the epidemiology of multihost pathogen systems at the community level.     

EXISTENCE: WHO NEEDS IT? THE NON‐IDENTITY PROBLEM AND MERELY POSSIBLE PEOPLE

In formulating procreative principles, it makes sense to begin by thinking about whose interests ought to matter to us. Obviously, we care about those who exist. Less obviously, but still uncontroversially, we care about those who will exist. Ought we to care about those who might possibly, but will not actually, exist? Recently, unusual positions have been taken regarding merely possible people and the non‐identity problem. David Velleman argues that what might have happened to you – an existent person – often doesn't merit moral consideration since the alternative person one would have been had what might have happened actually happened is a merely possible person about whom one has no reason to care. He argues that his way of thinking can eliminate the non‐identity problem. Caspar Hare argues that merely possible people have interests and are morally relevant. He argues that we can solve the non‐identity problem by rejecting the view that merely possible people are morally irrelevant. Both Hare and Velleman argue that focusing on one's de dicto rather than on one's de re children can help us avoid the non‐identity problem. I analyze the role that merely possible, nonexistent hypothetical entities ought to play in our moral reasoning, especially with regard to procreation. I refute both Velleman's and Hare's views and demonstrate the difficulties we encounter when we try to apply their views to common non‐identity cases. I conclude with the common‐sense view regarding who matters, morally: only those who do, did, or will exist.     

The heterogeneity of ion channels in chromaffin granule membranes

Chromaffin granules are involved in catecholamine synthesis and traffic in the adrenal glands. The transporting membrane proteins of chromaffin granules play an important role in the ion homeostasis of these organelles. In this study, we characterized components of the electrogenic ⁸⁶Rb⁺ flux observed in isolated chromaffin granules. In order to study single channel activity, chromaffin granules from the bovine adrenal medulla were incorporated into planar lipid bilayers. Four types of cationic channel were found, each with a different conductance. The unitary conductances of the potassium channels are 360 ± 10 pS, 220 ± 8 pS, 152 ± 8 pS and 13 ± 3 pS in a gradient of 450/150 mM KCl, pH 7.0. A multiconductance potassium channel with a conductivity of 110 ± 8 pS and 31 ± 4 pS was also found. With the exception of the 13 pS conductance channel, all are activated by depolarizing voltages. One type of chloride channel was also found. It has a unitary conductance of about 250 pS in a gradient of 500/150 mM KCl, pH 7.0.     

John Salter and the Ediacara Fauna of the Longmyndian Supergroup

John W. Salter's papers of 1856 and 1857 reported trace and body fossils from rocks of the Longmyndian Supergroup, Shropshire, that conventional wisdom had deemed literally “Azoic.” The significance of this work is reflected by its mention in On the Origin of Species, where it is cited as evidence for the existence of life prior to the Cambrian radiation. This study of Salter's historic specimens combined with recent field studies confirms that these structures likely represent microbial rather than metazoan markings. Nevertheless, this review confirms Salter as the unheralded founder of Precambrian palaeontology, many years before the existence of a Precambrian fossil record was widely known. This study also gives credit to a highly skilled palaeontologist, who appears to have struggled with psychological problems throughout his life. Salter had once been Adam Sedgwick's “youthful and cheerful companion” in the field, prior to embarking on an initially successful Geological Survey career. He was a widely renowned expert on Palaeozoic palaeontology, especially trilobites, but eventually fell into serious depression, which culminated in his suicide in 1869. Study and reinterpretation of his original materials reaffirms the importance of Salter's discoveries, and the Longmynd for our understanding of late Ediacaran palaeobiology.     

Effects of field size when using Kerley's histological method for determination of age at death

The field size at which a bone is read affects the results obtained when using Kerley's histological method for age estimation, even after applying the recommended correction factor. Whereas there is no tendency for any one of three field sizes tested to consistently underestimate or overestimate age, a field size closest to that used by Kerley in his original study had significantly lower variances for its age estimates, and thus provides greater reliability. This particular field size yields more precise estimates because it is sampling a pattern and number of structures more similar to that of Kerley. Correction factors cannot equalize the counts of osteons and osteon fragments because of spatial variations in the distributions of these histological structures. A field size similar to that used by Kerley in gathering the data from which he developed his regression equations must be used to assure that the same pattern and number of structures is being sampled. For this reason, we suggest a field size as close to 2.06 mm² as possible be used when employing Kerley's method.     

Tracking the cargo of extracellular symbionts into host tissues with correlated electron microscopy and nanoscale secondary ion mass spectrometry imaging

Extracellular bacterial symbionts communicate biochemically with their hosts to establish niches that foster the partnership. Using quantitative ion microprobe isotopic imaging (nanoscale secondary ion mass spectrometry [NanoSIMS]), we surveyed localization of ¹⁵N‐labelled molecules produced by the bacterium Vibrio fischeri within the cells of the symbiotic organ of its host, the Hawaiian bobtail squid, and compared that with either labelled non‐specific species or amino acids. In all cases, two areas of the organ's epithelia were significantly more ¹⁵N enriched: (a) surface ciliated cells, where environmental symbionts are recruited, and (b) the organ's crypts, where the symbiont population resides in the host. Label enrichment in all cases was strongest inside host cell nuclei, preferentially in the euchromatin regions and the nucleoli. This permissiveness demonstrated that uptake of biomolecules is a general mechanism of the epithelia, but the specific responses to V. fischeri cells recruited to the organ's surface are due to some property exclusive to this species. Similarly, in the organ's deeper crypts, the host responds to common bacterial products that only the specific symbiont can present in that location. The application of NanoSIMS allows the discovery of such distinct modes of downstream signalling dependent on location within the host and provides a unique opportunity to study the microbiogeographical patterns of symbiotic dialogue.