Phylogenomics of the dog and fox family (Canidae,Carnivora) revealed by chromosome painting

Canid species (dogs and foxes) have highly rearranged karyotypes and thus represent a challenge for conventional comparative cytogenetic studies. Among them, the domestic dog is one of the best-mapped species in mammals, constituting an ideal reference genome for comparative genomic study. Here we report the results of genome-wide comparative mapping of dog chromosome-specific probes onto chromosomes of the dhole, fennec fox, and gray fox, as well as the mapping of red fox chromosome-specific probes onto chromosomes of the corsac fox. We also present an integrated comparative chromosome map between the species studied here and all canids studied previously. The integrated map demonstrates an extensive conservation of whole chromosome arms across different canid species. In addition, we have generated a comprehensive genome phylogeny for the Canidae on the basis of the chromosome rearrangements revealed by comparative painting. This genome phylogeny has provided new insights into the karyotypic relationships among the canids. Our results, together with published data, allow the formulation of a likely Canidae ancestral karyotype (CAK, 2n = 82), and reveal that at least 6–24 chromosomal fission/fusion events are needed to convert the CAK karyotype to that of the modern canids. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

组织工程化同种异体椎间盘移植的动物实验研究

目的观察组织工程技术的运用能否延缓椎间盘移植后的退行性改变。方法将髓中受细胞复合至同种异体椎间盘,体外培养后植入犬L4／k椎间隙作为实验组（A组）,对照组（B组）行同种异体椎间髓移植。使用影像学、生物力学及组织学分析评估植入椎间盘的转归并行组间比较。结果移植椎间盘可与宿主椎体实现骨性融合。对照组椎间盘术后退变明显,12周时其椎间盘高度及髓核信号比灰度值明显低于实验组,稳定性丧失明显;组织学观察发现实验组移植椎间盘结构保持较好,髓核细胞数量较多,排列规则;对照组髓核形态保持欠佳,结构紊乱,髓核细胞数量减少,退行性改变明显。结论通过复合种子细胞实现异体椎间盘的组织工程化可有效延缓椎间盘移植后的退行性改变。     

比例辅助通气、压力支持通气对健康和急性肺损伤犬心肺功能影响的比较

目的 比较比例辅助通气(PAV)和压力支持通气(PSV)模式对健康和急性肺损伤(ALI)犬心肺功能的影响.方法 对10例健康和急性肺损伤犬先用间歇正压通气(IPPV)模式通气,同时计算弹性阻力(Ers)和粘性阻力(Rrs),然后将模式改为PAV,设置辅助比例60%,稳定后记录呼吸力学、血气和血流动力学参数的变化.再将模式改为PSV,设置支持压力分别使得气道峰压(Ppeak)和潮气量与PAV时相似.稳定后记录各项参数.结果 对于健康犬,PSV与PAV60%潮气量相同时其平均气道压(mPaw)、呼吸机呼吸功(WOBv)较PAV60%时高,差异有统计学意义,余各指标间差异无统计学意义.PSV和PAV比较,对血流动力学影响差异无统计学意义.对于ALI犬,PSV潮气量与PAV60%相同时,其Ppeak和mPaw较PAV60%高,差异有统计学意义,余指标差异无统计学意义.对血流动力学的影响,PSV潮气量与PAV60%相同时,其肺毛细血管楔压(PCWP)较PAV60%增高,差异有统计学意义.结论 PAV与PSV相比,其气道压力低,对血流动力学影响较小.     

缺血后处理减轻犬肾缺血再灌注损伤的作用

目的 探讨缺血后处理减轻犬肾缺血再灌注损伤的作用及其相关机制.方法 随机将犬分为假手术组、缺血再灌注组和缺血后处理组,每组5只.假手术组:犬麻醉后,取其腹正中切口进入腹腔,游离双侧肾脏,切除右肾后,关腹.缺血再灌注组:手术操作与假手术组相同,仅在切除右肾和游离左肾之后,将左肾动、静脉夹闭60 min,然后开放血管.缺血后处理组:手术操作与缺血再灌注组相同,仅在肾动、静脉被夹闭60 min后,以再灌注(开放血管)30 s、夹闭血管30 s为1个循环,共进行6次循环,然后完全放开血管.分别于术后24、48及72 h采集犬静脉血2 ml,使用全自动生化分析仪测定各组犬血清肌酐(Cr)和尿素氮(BIJN)水平;术后第3天取犬肾组织,采用硫代巴比妥酸法测定丙二醛(MDA)含量,采用黄嘌呤氧化酶法测定超氧化物歧化酶(SOD)活性,采用化学比色法测定髓过氧化物酶(MPO)活性,并观察犬肾组织的病理改变和细胞凋亡情况.结果 术后各时间点,缺血再灌注组、缺血后处理组和假手术组犬的血清Cr和BUN水平均依次降低,3组间比较,差异均有统计学意义(P<0.05).术后第3天,缺血再灌注组、缺血后处理组和假手术组犬肾组织中SOD活性依次升高,而MDA含量和MPO活性均依次降低,3组间比较,差异均有统计学意义(P<0.05).假手术组肾小球和肾小管结构正常,未见明显病理改变;缺血再灌注组肾间质水肿,大量炎症细胞浸润,肾小管上皮细胞刷状缘消失,大量上皮细胞坏死、脱落,管腔扩张,其中可见大量管型;缺血后处理组可见肾间质轻度水肿,肾小管上皮细胞扁平,部分刷状缘消失、坏死,偶见管型,管周血管有少量淤血.假手术组、缺血再灌注组、缺血后处理组犬肾的细胞凋亡指数分别为2.7±1.3、28.4±6.2和15.4±4.1,3组间比较,差异均有统计学意义(P<0.05).结论 缺血后处理能减轻犬肾缺血再灌注损伤,其机制可能与缺血后处理减少氧自由基的产生、抑制细胞凋亡及减少炎症细胞浸润有关.     

去细胞猪主动脉瓣移植于犬腹主动脉内构建组织工程瓣

目的 探讨在犬腹主动脉内构建组织工程心脏瓣膜的实验方法。方法 将预种犬血管间质细胞和内皮细胞的去细胞猪主动脉瓣叶(猪瓣),移植于6条犬的腹主动脉内,于术后4,6,8和10周对移植瓣叶进行形态、组织结构及免疫组化染色观察。结果 (1)移植术后4周时瓣叶周边有多层细胞长入,新细胞外基质形成,原支架组织部分吸收。(2)10周末猪瓣组织完全吸收,为宿主细胞及新合成的细胞外基质取代。基质中间质细胞主要为成纤维细胞和肌纤维母细胞。细胞外基质成分主要为Ⅰ、Ⅲ型胶原和少量弹力纤维,并含有中性和酸性黏多糖。(3)内皮细胞覆盖于瓣叶表面。结论 (1)移植于犬腹主动脉内的去细胞猪瓣于移植术后10周末基本构成组织工程瓣叶;(2)腹主动脉内异位移植是一种可供选择的实验研究方法。     

Evolution in coyotes (Canis latrans) in response to the megafaunal extinctions

Living coyotes modify their behavior in the presence of larger carnivores, such as wolves. However, little is known about the effects of competitor presence or absence on morphological change in coyotes or wolves over long periods of time. We examined the evolution of coyotes and wolves through time from the late Pleistocene, during which many large carnivorous species coexisted as predators and competitors, to the Recent; this allowed us to investigate evolutionary changes in these species in response to climate change and megafaunal extinctions at the end of the Pleistocene. We measured postcranial skeletal morphologies of wolves (Canis lupus) and coyotes (C. latrans) from Pleistocene-aged tar deposits, as well as early, mid, and recent Holocene populations of both. We found few morphological differences between Pleistocene and Holocene wolf populations. Conversely, we found many differences in coyotes: Pleistocene coyotes were larger and more robust than Holocene populations. However, within 1,000 y of the megafaunal extinctions, coyotes are morphologically indistinguishable from modern populations. We cannot attribute these differences directly to climate change because modern coyotes do not follow Bergmann's rule, which states body size increases with decreasing temperature. Instead, we suggest that Pleistocene coyotes may have been larger and more robust in response to larger competitors and a larger-bodied prey base. Although we cannot separate competition from predator-prey interactions, this study indicates that the effects of biotic interactions can be detected in the fossil record.     

Running,jumping, hunting,and scavenging: Functional analysis of vertebral mobility and backbone properties in carnivorans

Carnivorans are well-known for their exceptional backbone mobility, which enables them to excel in fast running and long jumping, leading to them being among the most successful predators amongst terrestrial mammals. This study presents the first large-scale analysis of mobility throughout the presacral region of the vertebral column in carnivorans. The study covers representatives of 6 families, 24 genera and 34 species. We utilized a previously developed osteometry-based method to calculate available range of motion, quantifying all three directions of intervertebral mobility: sagittal bending (SB), lateral bending (LB), and axial rotation (AR). We observed a strong phylogenetic signal in the structural basis of the vertebral column (vertebral and joint formulae, length proportions of the backbone modules) and an insignificant phylogenetic signal in most characteristics of intervertebral mobility. This indicates that within the existing structure (stabilization of which occurred rather early in different phylogenetic lineages), intervertebral mobility in carnivorans is quite flexible. Our findings reveal that hyenas and canids, which use their jaws to seize prey, are characterized by a noticeably elongated cervical region and significantly higher SB and LB mobility of the cervical joints compared to other carnivorans. In representatives of other carnivoran families, the cervical region is very short, but the flexibility of the neck (both SB and LB) is significantly higher than that of short-necked odd-toed and even-toed ungulates. The lumbar region of the backbone in carnivorans is dorsomobile in the sagittal plane, being on average ~23° more mobile than in artiodactyls and ~38° more mobile than in perissodactyls. However, despite the general dorsomobility, only some representatives of Canidae, Felidae, and Viverridae are superior in lumbar flexibility to the most dorsomobile ungulates. The most dorsomobile artiodactyls are equal or even superior to carnivorans in their ability to engage in dorsal extension during galloping. In contrast, carnivorans are far superior to ungulates in their ability to engage ventral flexion. The cumulative SB in the lumbar region in carnivorans largely depends on the mode of running and hunting. Thus, adaptation to prolonged and enduring pursuit of prey in hyenas is accompanied by markedly reduced SB flexibility in the lumbar region. A more dorsostable run is also a characteristic of the Ursidae, and the peculiar maned wolf. Representatives of Felidae and Canidae have significantly more available SB mobility in the lumbar region. However, they fully engage it only occasionally at key moments of the hunt associated with the direct capture of the prey or when running in a straight line at maximum speed.     

管状胃制作宽度对犬胃组织微循环灌注及反流功能的影响

目的 探索管状胃胃体宽度对胃组织微循环灌注及反流功能、术后吻合口瘘的影响.方法 90只雄性比格犬随机分为A、B、C组,每组30只,分别制作管状胃胃体宽度为2/3、1/2、1/3原胃模型.比较3组手术时间、术中出血量及术后吻合口瘘发生率;采用超声造影技术比较3组胃组织微循环灌注情况;采用pH监测仪监测管状胃内pH值、反流次数及时间.结果 C组手术时间显著长于A、B组(P<0.05),B组显著长于A组(P<0.05);C组术中出血量显著多于A、B组(P<0.05);B组术后吻合口瘘发生率显著低于A、C组(P<0.05).B组曲线下面积显著高于A、C组(P<0.05),A组显著高于C组(P<0.05);B组曲线上升支斜率显著高于A、C组(P<0.05);B组曲线达峰时间均少于A、C组(P<0.05).A组胃内pH<4总时间显著长于B、C组(P<0.05),B组显著长于C组(P<0.05);A组反流次数显著多于B、C组(P<0.05),B组显著多于C组(P<0.05);A组最长反流时间显著长于B、C组(P<0.05),B组显著长于C组(P<0.05).结论 管状胃宽度对术后吻合口瘘发生率、微循环灌注及反流情况影响巨大,过宽及过窄均不好,管状胃宽度为原胃1/2具有较高的应用价值.     

Iterative adaptive radiations of fossil canids show no evidence for diversity-dependent trait evolution

A long-standing hypothesis in adaptive radiation theory is that ecological opportunity constrains rates of phenotypic evolution, generating a burst of morphological disparity early in clade history. Empirical support for the early burst model is rare in comparative data, however. One possible reason for this lack of support is that most phylogenetic tests have focused on extant clades, neglecting information from fossil taxa. Here, I test for the expected signature of adaptive radiation using the outstanding 40-My fossil record of North American canids. Models implying time- and diversity-dependent rates of morphological evolution are strongly rejected for two ecologically important traits, body size and grinding area of the molar teeth. Instead, Ornstein–Uhlenbeck processes implying repeated, and sometimes rapid, attraction to distinct dietary adaptive peaks receive substantial support. Diversity-dependent rates of morphological evolution seem uncommon in clades, such as canids, that exhibit a pattern of replicated adaptive radiation. Instead, these clades might best be thought of as deterministic radiations in constrained Simpsonian subzones of a major adaptive zone. Support for adaptive peak models may be diagnostic of subzonal radiations. It remains to be seen whether early burst or ecological opportunity models can explain broader adaptive radiations, such as the evolution of higher taxa.A central prediction of modern adaptive radiation theory is that rates of diversification and phenotypic evolution are fastest early in clade history and subsequently slow as niches become saturated (1). This prediction is derived in large part from the writings of Simpson (2, 3), who suggested that fast rates of phenotypic evolution are required during the early phases of adaptive radiation to move lineages rapidly through inadaptive phases of the adaptive landscape to a new peak. Although the fossil record provides many examples of rapid early accumulation of morphological disparity (4–10), direct evidence for early rapid rates of phenotypic evolution, a so-called “early burst,” has proved rare in phylogenetic comparative data (11). There are several plausible explanations for why early bursts are seldom observed. For example, temporally declining rates are difficult to detect in datasets comprising only extant taxa, and comparative methods are extremely sensitive to noise from convergence or measurement error (11, 12). Incorporation of fossil taxa in phylogenetic tests for early bursts can improve detection of these patterns (13), although isolated analyses of subclades within a larger adaptive radiation may fail to show evidence of declining disparity with time if rates have already significantly decreased, even when fossil species are sampled (14).An alternative explanation for the lack of early bursts in comparative data is that ecological opportunity, not time, is the key determinant of rates of morphological evolution. If opportunity is the dominant force driving rates of morphological evolution in adaptive radiation, then the early burst model should be a particularly poor fit when clade age is a weak predictor of species richness. Patterns of diversity through time in the fossil record strongly suggest that diversity-dependent speciation and extinction dynamics are common (15–17) and weak or negative relationships between clade age and species richness are increasingly recognized in molecular phylogenies (18–20). To test the role of ecological opportunity in driving the morphological component of adaptive radiation more explicitly, Mahler et al. (21) developed a novel approach to model rates of morphological evolution as function of estimated past diversity at nodes of a time-calibrated molecular phylogeny (a similar method can be found in ref. 22). Using estimated lineage diversity as a proxy for past ecological opportunity in island communities of Anolis lizards, they found strong support for diversity dependence of evolutionary rates for body size and limb bone lengths, both of which influence habitat use and performance (21). This result would seem to lend support to a primary role for ecological opportunity in regulating rates of morphological evolution during adaptive radiation. It remains to be tested, however, whether diversity dependence can provide a compelling mechanism to explain patterns of morphological disparity through time in more general contexts, such as on continents, or over longer geological times scales.In this article, I test for diversity dependence of rates of body size and dental evolution in living and fossil members of the dog family, Canidae. Canids are an attractive system for such a study. Living canids exhibit a range of dietary and predatory behaviors that can be readily diagnosed for fossil species on the basis of craniodental traits (23, 24). The canid fossil record is also well sampled, yielding a diverse radiation of ∼140 species (25–27) that spans the Late Eocene (40 Mya) through present day. Perhaps most importantly, however, for the first 35 My of their evolutionary history, canids were restricted to and diversified exclusively within North America. If ecological opportunity plays a prominent role in regulating rates of morphological diversification over geological time scales, we should expect to find support for a link between diversity and the tempo of ecomorphological diversification in continental radiations with excellent fossil records, such as Canidae.