Cabinet of Curiosities: Venom Systems and Their Ecological Function in Mammals,with a Focus on Primates

Venom delivery systems (VDS) are common in the animal kingdom, but rare amongst mammals. New definitions of venom allow us to reconsider its diversity amongst mammals by reviewing the VDS of Chiroptera, Eulipotyphla, Monotremata, and Primates. All orders use modified anterior dentition as the venom delivery apparatus, except Monotremata, which possesses a crural system. The venom gland in most taxa is a modified submaxillary salivary gland. In Primates, the saliva is activated when combined with brachial gland exudate. In Monotremata, the crural spur contains the venom duct. Venom functions include feeding, intraspecific competition, anti-predator defense and parasite defense. Including mammals in discussion of venom evolution could prove vital in our understanding protein functioning in mammals and provide a new avenue for biomedical and therapeutic applications and drug discovery.     

Lung Development of Monotremes: Evidence for the Mammalian Morphotype

The reproductive strategies and the extent of development of neonates differ markedly between the three extant mammalian groups: the Monotremata, Marsupialia, and Eutheria. Monotremes and marsupials produce highly altricial offspring whereas the neonates of eutherian mammals range from altricial to precocial. The ability of the newborn mammal to leave the environment in which it developed depends highly on the degree of maturation of the cardio‐respiratory system at the time of birth. The lung structure is thus a reflection of the metabolic capacity of neonates. The lung development in monotremes (Ornithorhynchus anatinus, Tachyglossus aculeatus), in one marsupial (Monodelphis domestica), and one altricial eutherian (Suncus murinus) species was examined. The results and additional data from the literature were integrated into a morphotype reconstruction of the lung structure of the mammalian neonate. The lung parenchyma of monotremes and marsupials was at the early terminal air sac stage at birth, with large terminal air sacs. The lung developed slowly. In contrast, altricial eutherian neonates had more advanced lungs at the late terminal air sac stage and postnatally, lung maturation proceeded rapidly. The mammalian lung is highly conserved in many respects between monotreme, marsupial, and eutherian species and the structural differences in the neonatal lungs can be explained mainly by different developmental rates. The lung structure of newborn marsupials and monotremes thus resembles the ancestral condition of the mammalian lung at birth, whereas the eutherian newborns have a more mature lung structure. Anat Rec, 2009. © 2008 Wiley‐Liss, Inc.     

单孔和三孔电视胸腔镜治疗自发性气胸的对比研究

目的 探讨单孔与三孔电视胸腔镜治疗自发性气胸的临床疗效.方法 回顾性分析2012年4月-2013年4月就诊于咸阳市中心医院胸外科诊断为自发性气胸的患者58例,按照随机数字表法将患者随机分配至单孔电视胸腔镜组28例,三孔电视胸腔镜组30例,并用电话随访法进行随访.采用SPSS19.0统计学软件对两组患者的临床指标、并发症发病率及生存资料进行统计学分析.结果 与传统三孔电视胸腔镜手术相比,单孔电视胸腔镜手术具有术后住院时间更短(t=-4.151,P=0.001)、引流持续时间更短(t=-3.436,P=0.001)、切口满意度评分更高(t=-6.141,P=0.001)、术后6h疼痛视觉评分更低(t=-4.942,P=0.006)、术后24 h疼痛视觉评分更低(t=-3.326,P=0.02)及术后胸腔积液的发病率更低(Z=-2.096,P=0.036)的优点,但手术时间长(t=6.369,P=0.000),在其他并发症发病率、总生存时间(x2 =0.001,P=0.979)及中位无疾病进展生存时间(x2=1.797,P=0.180)方面差异无明显统计学意义(P＞0.05).结论 与三孔电视胸腔镜手术相比,单孔电视胸腔镜手术在住院时间短、术后疼痛轻等方面具有一定的优势,但不能明显缩短手术时间和改善患者术后生活质量.     

The oldest platypus and its bearing on divergence timing of the platypus and echidna clades

Monotremes have left a poor fossil record, and paleontology has been virtually mute during two decades of discussion about molecular clock estimates of the timing of divergence between the platypus and echidna clades. We describe evidence from high-resolution x-ray computed tomography indicating that Teinolophos, an Early Cretaceous fossil from Australia's Flat Rocks locality (121-112.5 Ma), lies within the crown clade Monotremata, as a basal platypus. Strict molecular clock estimates of the divergence between platypus and echidnas range from 17 to 80 Ma, but Teinolophos suggests that the two monotreme clades were already distinct in the Early Cretaceous, and that their divergence may predate even the oldest strict molecular estimates by at least 50%. We generated relaxed molecular clock models using three different data sets, but only one yielded a date overlapping with the age of Teinolophos. Morphology suggests that Teinolophos is a platypus in both phylogenetic and ecological aspects, and tends to contradict the popular view of rapid Cenozoic monotreme diversification. Whereas the monotreme fossil record is still sparse and open to interpretation, the new data are consistent with much slower ecological, morphological, and taxonomic diversification rates for monotremes than in their sister taxon, the therian mammals. This alternative view of a deep geological history for monotremes suggests that rate heterogeneities may have affected mammalian evolution in such a way as to defeat strict molecular clock models and to challenge even relaxed molecular clock models when applied to mammalian history at a deep temporal scale.