低氧对高原鼠兔和大鼠血液NO 与ET-1的影响

将Wistar大鼠暴露于3 780 m低氧环境,分别于24 h、2 wk及3 wk后采用酶联免疫法和硝酸还原酶法测定血液中的ET~(-1)和NO的含量,计算NO/ET~(-1)值,并与高原鼠兔比较,探讨低氧条件下大鼠与高原鼠兔血液中NO与ET~(-1)含量的变化趋势。结果表明,低氧24 h后,大鼠血液中NO和ET~(-1)的含量显著高于同海拔的高原鼠兔(P<0·01),而NO/ET~(-1)值无显著差异(P>0·05)。随着大鼠在高海拔停留时间的延长,血液中NO含量呈减少趋势,而ET~(-1)则有上升趋势,二者呈显著的负相关(r2=0·2416,P<0·01)。高原鼠兔NO/ET~(-1)值约为大鼠低氧2 wk和3 wk的2倍(P<0·01)。说明不同低氧暴露时间,高原鼠兔和大鼠的NO、ET~(-1)及NO/ET~(-1)值有显著差异,提示NO/ET~(-1)值可以作为有机体是否适应高原低氧环境的一个指标。     

不同海拔地区高原鼠兔探究性和静止代谢率的差异

环境的差异影响动物种群生活史对策的进化。对地理分布范围广的物种而言,栖息地环境差异大,不同种群的生活史对策亦存在显著差异。个性特征作为生活史的一部分,反映了动物对环境的适应模式。前期研究表明,不同海拔区域的高原鼠兔的生活史对策存在显著差异,然而,其个性特征及与能量代谢的关联性是否也存在差异,目前尚不清楚。2018年9-10月,分别在海拔3268 m的贵南县和3980 m的玛沁县测定当地高原鼠兔的探究性与静止代谢率。结果发现,高海拔雄性高原鼠兔的探究性显著低于低海拔雄性个体;高海拔雌性高原鼠兔体重矫正静止代谢率显著高于低海拔雌性个体。高海拔地区,雌性高原鼠兔的探究性和体重矫正静止代谢率呈显著正相关,雄性高原鼠兔的探究性和体重呈显著负相关;低海拔地区,高原鼠兔的探究性和体重矫正静止代谢率或体重之间均无显著相关性。该结果 表明,调整个性特征和能量代谢及其两者的关联性也是高原鼠兔适应不同海拔栖息地环境差异的生活史对策之一。     

The correlation of the size of the pinna and the auditory bulla in specialized desert rodents

Relation between size of pinna and auditory bulla in specialized desert rodents (families Allactagidae, Dipodidae, Gerbillidae, Heteromyidae, and genus Selevinia) is statistically significant and described by hyperbola. The empirical distribution of respective sizes can be interpreted as a total of two main trends. One is enlargement of the pinna, the bulla remains small (most of Allactagidae), another is enlargement of the bulla, the pinna remains small (Gerbillidae, Heteromyidae, Selevinia, most Dipodidae). A few species display moderate enlargement of both pinna and bulla, while in Euchoreutes they both are hypertrophied. Biomechanical preconditions are supposed to be following. Enlargement of the pinna is responsible for increasing of both sensitivity and locatory abilities of the hearing organ, while enlargement of the bulla is responsible for the first function only. So, the two main trends are results of selection of development of the hearing organ at the level of either pinna or bulla. It is shown by dispersion and correlation analyses that size of the parts of the hearing organ under investigation are correlated mostly with mobility and escaping mode. It is concluded therefore that the rodents characterized by active and speedy escaping from predation display the first of the above trends, while the rodents characterized by passive escaping from predation display the second trend.     

Hearing dimorphism, trait variation and conflicts over space in the thorax of the bushcricket Requena verticalis (Listroscelidinae: Tettigoniidae: Orthoptera)

The hearing system of Requena verticalis is sexually dimorphic. Previous work has shown size of the auditory spiracle determines absolute threshold and as female spiracles are, on average, larger than males, females are more sensitive to the main energy of the male call. In all measured traits in morphology and physiology, females showed lower coefficient of variation than males. This difference was significant for bulla volume and hearing threshold. In addition, female ear size covaries with thorax dimensions but this is not so in males. Such a finding suggests stabilising selection on ear size in females, perhaps explained by the requirement of females to recognise and locate the male. As the auditory bulla is larger in females than males, so occupying thoracic space, we suggest a possible trade-off in this brachypterous species between hearing sensitivity and sound production. Finally, we examine relative growth of body structures not associated with hearing and those that influence hearing sensitivity. Scaling, where traits are under strong selection, may result in allometry. Female hearing traits show positive allometry with absolute size and while the relationship between bulla volume and spiracle area was positively allometric in females this was not the case for males.     

Morphologische Untersuchungen am Mittelohr der Marsupialial

Morphological studies on the auditory bulla of marsupials The resent study on the comparative anatomy of the marsupial auditory bulla starts with that of the didelphids; ontogenetic data are included. It becomes clear from these comparisons, that the marsupial bulla is throughout composed of the same skeletal elements. Contrary to widespread opinion, there exists no good evidence for the existence of an entotympanic in any marsupial. The tympanic process of the petrosal develops relatively late in ontogeny as ‘additional bone’ (“Zuwachsknochen” of Starck ); the same holds true for the tympanic process of the alisphe-noid. Biometric study of the tymanic ring in didelhids reveals that the tympanic membrane does only slightly increase with skull size (pronounced negative allometry). It is surprising, however, that the data of the tympanic diameter do arrane at two distinct levels of regression. Several taxa of didelphids must have jumped at this level independently. The possible functional meanings of these data are briefly discussed.     

Allometry, bilateral asymmetry and sexual differences in the vocal tract of common eiders Somateria mollissima and king eiders S. spectabilis

Intraspecific sexual differences, high variation, and positive allometry of sexually-selected external display structures are common. Many sexually-selected anatomical specializations occur in the avian vocal tract but intraspecific variation and allometry have been investigated little. The tracheal bulla bulla syringealis occurs in males of most duck species. We quantified variation and size-scaling of the bulla, plus sexual differences in size of trachea, bronchi, and vocal muscles, for 62 common eiders Somateria mollissima and 51 king eiders S. spectabilis. Trends were similar in both species. Bullar ossification and definitive size occurred early in life: bullar size did not differ between first-year and older males. Bullar size did not vary more than size of other body parts (CVs of 3.4–7.0% for bullar length and breadth). Bullar size scaled to body size with negative allometry or isometry. Vocal muscles were 10–50% thicker in males than females, a much greater sexual difference than in body size (CVs of 3–6% on linear body-size variables). Vocal muscles were larger on the left side in both sexes and bilateral asymmetry was slightly more pronounced in males. Low variation and a trend towards negative allometry suggest that bullar size is under stabilizing selection; if bullar size affects vocal attributes of voice, then the latter cannot be condition-dependent. We recommend comparative research on vocal communication, vocal individuality and vocal-tract anatomy and function in eiders and other ducks.     

First Description of the Auditory Region of a Tremarctinae (Ursidae,Mammalia) Bear: The Case of Arctotherium angustidens

Here we present the first detailed morphological study of the auditory region of a tremarctine bear, the South American giant short-faced bear Arctotherium angustidens. We compared 19 specimens of A. angustidens with other tremarctines and ursines. Through the use of CT scans, we confirmed the presence of a recesus epitympanicus and an anterior incomplete septum of uncertain homology, not related with the septum bullae nor with the longitudinal septum formed by the ecto- and the entotympanic. A secondary crus formed by the lateral semicircular canal (LSC) with the posterior semicircular canal (PSC) of the inner ear was observed in A. angustidens, A. bonariense, Tremarctos ornatus, Ursus spelaeus, and Ursus arctos. This secondary crus was not previously reported for ursids. We also observed that the intraspecific variation in the auditory region of A. angustidens is related to 1) the position of the foramen postglenoideum, 2) the anterior projection of the bulla tympanica over the foramen lacerum and over the opening of the Eustachian tube (medial process of the bulla tympanica), and 3) the projection of the bulla tympanica over the posterior surface of the processus postglenoideus (tympanic process). In addition to this variation, we also identified the presence of interspecific variation in the external auditory region among Tremarctinae and Ursidae. These differences are related to the size of the processus mastoideus and the processus paraoccipitalis, the position of the foramen postglenoideum, and the presence/absence of contact between the bulla tympanica and the processus paraoccipitalis.     

高原鼢鼠和高原鼠兔红细胞低氧适应特征

为探讨高原鼢鼠对低氧高二氧化碳洞道生境及高原鼠兔对高海拔低氧生境的适应机制,用Sysmex SF-3000血细胞分析仪及聚丙烯酰胺凝胶电泳对两种高原动物的血常规及血红蛋白类型进行分析,后者采用聚丙烯酰胺凝胶电泳法。结果表明,高原鼢鼠和高原鼠兔的红细胞数(RBC)、红细胞压积(HCT)及平均红细胞容积(MCV)组间无显著差异(P>0.05),但高原鼢鼠和高原鼠兔的红细胞数显著高于SD大鼠,红细胞压积及平均红细胞容积均显著低于SD大鼠(P<0.05);高原鼢鼠的血红蛋白浓度(HBC)与SD大鼠无显著差异(P>0.05),但显著高于高原鼠兔的HBC(P<0.05)。高原鼢鼠血红蛋白主要有2种类型,高原鼠兔血红蛋白主要有3种类型,而SD大鼠血红蛋白主要有5种类型。从血红蛋白电泳迁移来看,2种高原动物血红蛋白类型有明显的趋同特征并与SD大鼠具有明显的差异。上述结果提示,长期适应高海拔低氧环境的高原动物的红细胞和血红蛋白表现出趋同进化,同时因生境和习性的差异又表现出各自的特异性。     

7,8,3'-Trihydroxyflavone, a potent small molecule TrkB receptor agonist, protects spiral ganglion neurons from degeneration both in vitro and in vivo

Most sensorineural hearing loss cases occur as a result of hair cell loss, which results in secondary degeneration of spiral ganglion neurons (SGNs). Substantial loss of SGNs reduces the benefit of cochlear implants, which rely on SGNs for transmitting signals to the central auditory centers. Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) play essential roles in cochlear development and are required for SGN survival. Here we report that 7,8,3'-trihydroxyflavone (7,8,3'-THF), which is a small molecule agonist of tyrosine receptor kinase B (TrkB), promoted SGN survival with high potency both in vitro and in vivo. The compound protected the SGNs in a TrkB-dependent manner, as its effects on SGNs disappeared when the TrkB was blocked. Application of 7,8,3'-THF in the bulla of conditional connexin26 (cCx26)-null mice dramatically rescued SGNs in the applied ear compared to untreated control cochlea in the same animal. Our findings suggest that 7,8,3'-THF is a promising therapeutic agent protecting the SGNs from degeneration both in vitro and in vivo.     

Changes in the composition of the auditory bulla in southern Solomon Islands populations of the grey cuscus, Phalanger orientalis breviceps (Marsupialia, Phalangeridae)

The auditory bulla is a much-scrutinized taxonomic character of mammals, which is generally regarded as showing a high degree of structural consistency within higher taxa. Observations of bulla variability in populations of the marsupial Phalanger orientalis from the Solomon Islands demonstrate considerable flexibility in bulla makeup, with variable incorporation of the squamosal into the tympanic floor. Studies of the ontogeny of the bulla in Phalanger show the presence of three ossification centres, including an entotympanic. Squamosal invasion of one of these ossificiation centres is seen as a possible result of inbreeding, arising from the mode of colonization of the Solomon Islands by this species. This suggests that, under certain conditions, considerable morphological plasticity may be induced within the selective constraints of bulla function.     

高原鼠兔血清无机元素含量的分析

测定分析了高原鼠兔血清电解质、无机元素、血清铁和总铁结合力, 并与人和其它实验动物的相应指标进行了比较。得出以下主要结论: 1.高原鼠兔血清电解质浓度不受生活环境和食物条件的影响, 其机体能自身调节血清离子浓度, 以维持电解质在血液中的相对衡定; 2.高原鼠兔血清铁含量与其栖息地海拔相关, 随海拔升高血清铁含量增加; 3.高原鼠兔通过增加运铁蛋白与铁的结合力作为适应高原低氧环境的方式之一。     

高原鼢鼠、高原鼠兔和大鼠肺表面活性物质组成和含量的比较

本研究通过分析肺表面活性物质(pulmonary surfactant,PS)组成和含量探讨高原鼢鼠(Myospalax baileyi)和高原鼠兔(Ochotona curzoniae)的低氧适应机制.高原鼢鼠和高原鼠兔各36只,捕捉于海拔3 600 m左右的青海省海南州贵德县拉脊山地区,36只Sprague-Daw...     

Patterns of variation in the tympanic bulla of tuco-tucos (Rodentia,Ctenomyidae, Ctenomys)

As subterranean rodents live in burrows and are constrained by the physics of their environment to vocalize, mainly in low frequencies, their expanded middle ear cavities are associated with enhanced lower-frequency hearing. Previous literature has widely acknowledged inflated tympanic bulla as a character to be found in the majority of the Ctenomys species. To explore the morphology of Ctenomys tympanic bulla, we studied a sample of 669 skulls, obtained from 21 species, for tympanic bulla size, volume, and internal structure. The study determined that bullar inflation does not seem to be the rule in Ctenomys and that the relationship between bullar size (volume) and skull size do not correspond to the phylogeny based on cytochrome b sequences thus probably being a species-specific adaptive characteristic. We also found that the internal bullar structure differs between taxa, depending on the relative contributions of cancellous (alveolar) and septate patterns to the partitioning of the bulla.     

Intraspecific morphological variation of the middle ear in the European badger,Meles meles (Carnivora: Mustelidae)

Many studies have been conducted about the information contained in the anatomy of the mammalian middle ear. Most of these only use a few specimens. Thus we aim to provide a quantitative analysis of the intraspecific and interspecific variations of the middle ear, focusing on the auditory bulla. For that purpose, we focused on the mustelids, as a quite generalist taxon and, more specifically, on the European badger, Meles meles. Our study includes two types of statistical methods. We first compared the mean of a subjectively chosen measure between individuals of the same species and between individuals of different species. We then used a multidimensional scaling procedure to cluster individuals according to different measures. We conclude that the middle ear varies effectively less intraspecifically than interspecifically. However, we think that the few anatomical parameters to measure in the auditory bulla involve using more specimens or focusing on geometric morphometrics in studies focusing on middle ear.     

Cranial morphology of the early tertiary Phenacolemur and its bearing on primate phylogeny

An early Eocene skull of the paromomyid Phenacolemur, a plesiadapoid primate, is described with particular emphasis on the ear region. The auditory bulla is composed of the petrosal and of a large ectotympanic plate which is outside of the bulla. The preserved morphology of the middle ear is distinctly more primitive than that of the older Plesiadapis. It cannot be determined with certainty whether Phenacolemur had the carotid circulation enclosed in bony tubes or not. The auditory bulla of early primates and relevant living ones is discussed and it is suggested that an extrabullar ectotympanic, as seen in all non-lemuriform fossil and extant primates, was probably the primitive ordinal condition, rather than the intrabullar ring-like ectotympanic in the Lemuriformes. Aspects of the carotid circulation are discussed as they pertain to the relationship of early Tertiary primates, living Tarsiiformes, Lemuriformes and Lorisiformes.     

Partitions in the carnivoran auditory bulla: their formation and significance for systematics

The common notion that the septa in the carnivoran auditory bulla are formed by the growth of bone edges inwards the bullar cavity is a mistaken assumption based on the data of the late 19th century. Intrabullar partitions are in fact a result of the differential resorption of the bulla internal surface during the growth of the external surface. A septum develops at the boundary between local, relatively independent, ‘inflations’ of the bulla wall. This explanation, given by Van Kampen in 1905 for the case of the Canidae and some Mustelidae, can be applied to the whole order, including the aeluroid families with their ‘bilaminar’ septum bullae. Such an approach seems to solve the problem of homology of the intrabullar septa throughout the Carnivora, a question which has long been confused because of insufficient knowledge of septum morphogenesis. The partitions can really be considered as indicators of independent attempts to increase the size of a middle‐ear cavity among the infraorders. This conclusion follows immediately from the difference between major carnivoran taxa in the arrangement of separate inflations on the bulla wall, which can be considered as additional sinuses enlarging the hypotympanic space. It is precisely this difference that conditions the relative contribution of several bones (mainly of the ectotympanic and caudal entotympanic) to the intrabullar septa. Thus, the initial topographies of the above sinuses – whichever subsequent bone modelling of septa occurs – represent unique patterns useful in the higher‐level systematics of the Carnivora.     

Geometric morphometrics of the skull of various murid rodents (Mammalia, Rodentia): relation of the skull shape to the trophic specialization

Presented is a brief overview of basic principles and notions of geometric morphometrics, a new approach to quantitative analysis of shape variations. This approach is applied to analysis of variation of the skull shape in the sample of 18 muroid genera belonging to the families Cricetidae, Arvicolidae and Gerbillidae. The skull shape is described by landmarks, and skulls are compared by resistant fit and superimposition methods. Under consideration is relation of skull shape to the trophic specialization, to family belonging, and to body size. Axial skull reveals more conspicuous relation to each of the factor analyzed as compared to mandible. Zygomatic region and tooth raw are most differentiable, while change of auditory bulla is of secondary effect. Transition from omnivorous through granivorous to grass-eating specialization involves the same trend in each of the family studied in the case of axial skull but not of mandible. Most dependent of trophic specialization appeared to be shape of axial skull rather then of mandible. Arvicolines are most specific in respect to the skull shape. Shape to size relation, although rather slight, also involves the same zygomatic-dental region. The results obtained indicate probably that geometric morphometrics does reveal variations in the skull shape that are free of the size effect.     

Adaptive population divergence and directional gene flow across steep elevational gradients in a climate‐sensitive mammal

The ecological effects of climate change have been shown in most major taxonomic groups; however, the evolutionary consequences are less well‐documented. Adaptation to new climatic conditions offers a potential long‐term mechanism for species to maintain viability in rapidly changing environments, but mammalian examples remain scarce. The American pika (Ochotona princeps) has been impacted by recent climate‐associated extirpations and range‐wide reductions in population sizes, establishing it as a sentinel mammalian species for climate change. To investigate evidence for local adaptation and reconstruct patterns of genomic diversity and gene flow across rapidly changing environments, we used a space‐for‐time design and restriction site‐associated DNA sequencing to genotype American pikas along two steep elevational gradients at 30,966 SNPs and employed independent outlier detection methods that scanned for genotype‐environment associations. We identified 338 outlier SNPs detected by two separate analyses and/or replicated in both transects, several of which were annotated to genes involved in metabolic function and oxygen transport. Additionally, we found evidence of directional gene flow primarily downslope from high‐elevation populations, along with reduced gene flow at outlier loci. If this trend continues, elevational range contractions in American pikas will likely be from local extirpation rather than upward movement of low‐elevation individuals; this, in turn, could limit the potential for adaptation within this landscape. These findings are of particular relevance for future conservation and management of American pikas and other elevationally restricted, thermally sensitive species.     

不同海拔高原鼠兔个性特征与SERT基因多态性关联

个性特征是指动物个体间稳定、可遗传的行为差异,与相关基因多态性有关,反映了动物对环境的适应模式,探究个性相关基因变异,将有助于更好地理解动物对环境的适应与进化机制。本文以高原鼠兔 (Ochotona curzoniae) 为对象,研究了5个不同海拔地区高原鼠兔的个性 (探究性、勇敢性和温顺性) 差异特征,并检测了个性相关基因5-羟色胺转运体 (SERT) 的单核苷酸多态性 (SNP) 和mRNA表达。结果发现,高海拔地区高原鼠兔的探究性和勇敢性显著高于低海拔地区,而高海拔地区高原鼠兔SERT基因mRNA表达量显著低于低海拔地区,提示不同海拔高原鼠兔个性特征差异可能与SERT基因mRNA表达有所关联。进一步检测不同海拔地区高原鼠兔SERT基因多态性及其分布差异情况,发现该基因存在6个SNP (其中5个位于外显子3,1个位于外显子5 );不同海拔地区鼠兔基因分布差异分析显示外显子5的c.A1063C 同义突变与海拔之间存在显著相关,高海拔地区该位点CC基因型分布频率显著高于低海拔地区;c.A1063C的基因型虽然与探究性、勇敢性无显著相关,但与温顺性显著相关。综上所述,随着海拔升高,高原鼠兔探究性和勇敢性增加,这有利于动物获取更多的食物资源,进而增加其生存机会。与此同时,SERT基因多态性显示与不同海拔地区的生存环境相适应的特征,且与温顺性有关,暗示不同海拔高原鼠兔个性差异可能与SERT基因SNP的差异有关。本研究从基因表达与突变的角度尝试阐述高原鼠兔适应不同海拔环境的行为差异,显示了不同海拔地区高原鼠兔行为生存策略潜在的分子机制。