Origin of whales in epicontinental remnant seas: new evidence from the early eocene of pakistan

Pakicetus inachus from the early Eocene of Pakistan is the oldest and most primitive cetacean known. The dentition of Pakicetus resembles that of carnivorous mesonychid land mammals as well as middle Eocene cetaceans. The otic region of the cranium lacks characteristic specializations of whales necessary for efficient directional hearing under water. Pakicetus occurs with a land-mammal fauna in fluvial sediments bordering epicontinental Eocene remnants of the eastern Tethys seaway. Discovery of Pakicetus strengthens earlier inferences that whales originated from terrestrial carnivorous mammals and suggests that whales made a gradual transition from land to sea in the early Eocene, spending progressively more time feeding on planktivorous fishes in shallow, highly productive seas and embayments associated with tectonic closure of eastern Tethys.     

Specialized face learning is associated with individual recognition in paper wasps

We demonstrate that the evolution of facial recognition in wasps is associated with specialized face-learning abilities. Polistes fuscatus can differentiate among normal wasp face images more rapidly and accurately than nonface images or manipulated faces. A close relative lacking facial recognition, Polistes metricus, however, lacks specialized face learning. Similar specializations for face learning are found in primates and other mammals, although P. fuscatus represents an independent evolution of specialization. Convergence toward face specialization in distant taxa as well as divergence among closely related taxa with different recognition behavior suggests that specialized cognition is surprisingly labile and may be adaptively shaped by species-specific selective pressures such as face recognition.     

An aegialodontid upper molar and the evolution of mammal dentition

The most obvious key synapomorphy of the therian mammals is the tribosphenic pattern of their molars. Tribosphenic teeth are capable of both shearing and grinding, which substantially increase effectiveness of food processing and, in turn, permit evolution of a wide range of dietary specializations. Functional tribospheny developed repeatedly during mammalian evolution but was successful only in the Boreosphenida. The earliest stage in the development of boreosphenidan tribospheny has remained poorly understood, being documented only by lower molars of aegialodontids. Here, we report a known upper molar of an aegialodontid mammal, Kielantherium, from the Early Cretaceous of Mongolia.     

Physiological constraint on feeding behavior: intestinal membrane disaccharidases of the starling

Animals clearly choose what they eat and can even choose among chemically different sugars. The physiological and biochemical mechanisms that constrain feeding choices are largely unknown. In this study, European starlings (Sturnus vulgaris) preferred mixture solutions of D-glucose plus D-fructose to equimolar (double molar caloric value) solutions of sucrose. Intubation feeding of sucrose did not increase blood glucose levels. Sucrose is a useless energy source for these birds because they lack a single digestive enzyme (sucrase) on the small intestinal brush border membrane. However, the membranes possessed separate maltase and isomaltase disaccharidases. This expression pattern and expression patterns of membrane disaccharidases among mammals suggest a role for intestinal enzymes in the coevolutionary interactions between vertebrates and their plant food sources.     

Skeleton of diacodexis, oldest known artiodactyl

A nearly complete skeleton of early Eocene Diacodexis, the oldest known member of the mammalian order Artiodactyla, is described. Its slender, elongate limb elements indicate that Diacodexis was highly cursorial and closer in postcranial adaptations to tragulids and other primitive ruminants than to living or extinct nonruminant artiodactyls. Its skeletal specializations call into question the widespread notion that Diacodexis was the ancestor of all later artiodactyls.     

METTL21C蛋白的序列特征、三维结构及分子进化

METTL21C蛋白作为甲基转移酶参与多种细胞进程的翻译后修饰,在生命活动中发挥重要的调控作用。从蛋白质信息数据库UniprotKB中选取36个不同代表物种的METTL21C蛋白作为研究对象,理化参数分析显示一级序列中氨基酸残基个数差异较大,平均为254个氨基酸残基,大多为偏酸亲水性蛋白。系统进化树显示36种METTL21C蛋白共分为哺乳类、爬行类、鸟类和鱼类4支,与物种的亲缘进化关系基本吻合。多序列比对和motif分析结果表明不同物种METTL21C蛋白的序列相似度较高,10个motif序列几乎覆盖了全长多肽链,大都含有motif 1～motif 5,但N端序列差异较大,在哺乳动物中包含特有的motif 7、motif 8和motif 10,而在多种鸟类中有大段序列缺失。结构对比分析发现不同物种METTL21C蛋白的空间构象绝大部分区域近乎完全重叠,仅少部分自由度较高的局部肽段有一定程度的差异,表明不同物种METTL21C在进化过程中一级序列有一定的差异,但是空间结构极为相似。以人METTL21C为蛋白质互作网络中心,直接相关蛋白质共11种,间接相关蛋白质共9种,说明METTL21C直接或间接参与多种细胞进程,调控机体的生命活动,为进一步深入研究METTL21C的生物学功能及其分子机制提供了理论基础。     

地震灾后北川村庄小兽种群动态

为了调查灾后北川村庄小兽种群动态变化,掌握小兽种群数量及变化规律,防止灾后兽害及自然疫源性疾病爆发.从2010年1月至2011年7月,每季度采用夹夜法对北川村庄进行小兽种群动态调查.整个调查期间捕获小兽176只,分属2目2科3属4种,捕获率为10.88％,其中四川短尾鼦为优势种,占捕获数的94.89％.调查期间,小兽种群数量在2010年10月为最高峰,每年4、7月为其繁殖高峰期,雌体怀孕率为41.56％,平均胎仔数为4.16个,雄体睾丸下降率为69.89％.不同季节、不同年度间小兽种群数量存在差异,可能受栖息环境改变及季节、气候、食物等因素影响.     

Homo erectus calvarium from the Pleistocene of Java

A Homo erectus calvarium [Sambungmacan 4 (Sm 4)] was recovered from Pleistocene sediments at Sambungmacan in central Java. Micro-computed tomography analysis shows a modern human-like cranial base flexion associated with a low platycephalic vault, implying that the evolution of human cranial globularity was independent of cranial base flexion. The overall morphology of Sm 4 is intermediate between that of earlier and later Javanese Homo erectus; apparent morphological specializations are more strongly expressed in the latter. This supports the hypothesis that later Pleistocene Javanese populations were substantially isolated and made minimal contributions to the ancestry of modern humans.     

A Late Jurassic digging mammal and early mammalian diversification

A fossil mammal from the Late Jurassic Morrison Formation, Colorado, has highly specialized teeth similar to those of xenarthran and tubulidentate placental mammals and different from the generalized insectivorous or omnivorous dentitions of other Jurassic mammals. It has many forelimb features specialized for digging, and its lumbar vertebrae show xenarthrous articulations. Parsimony analysis suggests that this fossil represents a separate basal mammalian lineage with some dental and vertebral convergences to those of modern xenarthran placentals, and reveals a previously unknown ecomorph of early mammals.     

东北地区兽类分布格局的统计分析

应用多元统计分析中的因子分析和聚类分析方法,使用Spss统计软件系统对东北地区94个市县的兽类分布格局进行了统计分析.根据兽类在各个特定分布区的分布特点,并结合自然地理条件以及东北地区兽类动物地理分布格局,将东北地区兽类动物地理区划划分为5个区.结果表明:兽类的分布格局与食物组成、栖息地类型密切相关,区域环境一致性较高的地区,其兽类区系成分相似性亦较高,聚类结果一致性较强.     

南漳县烤烟新品种比较试验研究

为了筛选出适应南漳烟区的栽培品种,2011年对烟草新品种(系)A9进行大田生产示范。结果表明:新品种(系)均表现为长势强,生长整齐,植株筒形,烟叶落黄均匀,易烘烤,外观质量好。在抗病性方面,新品种(系)对普通花叶病具有良好的抗性;在经济性状方面,A9的产量、产值、优质烟率均优于K326。A9整体表现优于K326,在南漳县具有较好的推广价值。     

Cretaceous sauropods from the sahara and the uneven rate of skeletal evolution among dinosaurs

Lower Cretaceous fossils from central Niger document the succession of sauropod dinosaurs on Africa as it drifted into geographic isolation. A new broad-toothed genus of Neocomian age ( approximately 135 million years ago) shows few of the specializations of other Cretaceous sauropods. A new small-bodied sauropod of Aptian-Albian age ( approximately 110 million years ago), in contrast, reveals the highly modified cranial form of rebbachisaurid diplodocoids. Rates of skeletal change in sauropods and other major groups of dinosaurs are estimated quantitatively and shown to be highly variable.     

Coexistence of clones in a heterogeneous environment

Two genetically distinct clones of the asexual triploid fish Poeciliopsis 2 monacha-lucida inhabit the Rio del Fuerte of northwestern Mexico. Their coexistence apparently depends on feeding specializations that result in partitioning of the limited food resources in the desert streams. The findings suggest that these asexual organisms have sufficient clonal diversity to occupy a broad, heterogeneous, adaptive zone.     

The origin of the turtle body plan: bridging a famous morphological gap

A restudy of pareiasaurs reveals that these primitive reptiles are the nearest relatives of turtles. The two groups share numerous derived characters, such as a reduced presacral count, an acromion process, and a trochanter major, which are absent in other basal amniotes. Many traits long thought specific to chelonians also occur in pareiasaurs and must have evolved before the distinctive turtle shell appeared. Evidence uniting captorhinid or procolophonoids with turtles is shown to be weak. The phylogeny proposed here also suggests that certain features of the earliest turtle (Proganochelys) that have been interpreted as specializations, such as the large supratemporal and robust metacarpals, are primitive for turtles. In pareiasaurs, the osteoderms represent the precursors of the chelonian shell and the morphology of the anterior region is consistent with the idea that the shoulder girdle in turtles has migrated posteriorly into the rib cage.     

Study of Application of Isozymic Marker to Distinguish the Multiplasmic Lines of Maize

On the basis of previous work, the study of screening marker bands of maize ( Zea mays L. )isozyme was carried out. 11 multiplasmic lines were used as experimental materials. The different tissues at different development stages were taken for each material. DPAGE system and double vertical gel slabs were used. The experimental results are as follows: (1) POD: A total of 20 isozymic bands. (Fli)Mo17 and (su1)Mo17 possessed the POD1 and POD3, while POD7 was absent. (sh2)MoI7-POD15 and POD16. (bt1)Mo17-POD1, POD11. (Pop)Mo17-POD15. (wx)Mo17 did not possess the POD3, 4, 5, 6, 8, 15, 16. The other lines possessed different POD. (2) EST: A total of 18 isozymic bands. (Fli)Mo17 possessed the EST 2, 17,but EST15 was absent. (su1)Mo17-EST13. (bt1)Mo17-EST6, 12, 14. (Pop)Mo17 possessed the EST12, but EST2, 8, 11, 13, 14 were absent. For the other multiplasmic lines, some possessed this EST, some possessed other EST. (3)According to the above data, some specific isozymic bands can be used as biochemical markers to distinguish these multiplasmic lines from each other.     

Hyperphoretic dispersal of a pyxidiophora anamorph

It has been suggested that Thaxteriola species and other minute, nonmycelial fungi associated with arthropods have phylogenetic relationships with the Laboulbeniales. However, direct development of the thallus of Thaxteriola from an ascospore of Pyxidiophora has now been discovered. Thaxteriola is specialized for dispersal by mites carried on pine bark beetles; other fungi dispersed by arthropods in this symbiotic assemblage rely primarily on arthropod specializations.     

小麦细胞质雄性不育系的分子细胞遗传学检测

利用 C-分带和 APAGE技术 ,对不同核型的具有粘果、易变、偏凸和二角山羊草细胞质的小麦雄性不育系进行了分子细胞遗传学标记检测。 APAGE分析发现 ,新不育系 5 - 1A和 7- 2 1A与 1BL/ 1RS易位型不育系77(2 )、82 2 2、偃师 9号、83(37) 6 5、80 (6 )同样均含有 1RS醇溶蛋白标记位点 Gld1B3。同时根尖染色体 C-分带显示5 - 1A和 7- 2 1A也含有 1RS端带。证明了 Gld1B3位点和 1RS端带可作为 1BL/ 1RS易位型不育系分子细胞遗传学标记。     

Convergent and alternative designs in the digital adhesive pads of scincid lizards

Prasinohaema virens, an arboreal scincid lizard, differs from its closest relatives in that it exhibits subdigital adhesive setae resembling those of anoles in shape and those of geckos in some aspects of size. The other scincid species in this genus as well as those in a presumed ancestral genus exhibit pad scales with surface folds and ruffles but no setae; at least one of these species uses an adhesive grip similar to that of anoles and geckos. Thus, there appear to be two strikingly different epidermal specializations for adhesive grip within this small radiation.     

An ossified Meckel's cartilage in two Cretaceous mammals and origin of the mammalian middle ear

An ossified Meckel's cartilage has been recovered from two early Cretaceous mammals from China. This element is similar to Meckel's cartilage in prenatal and some postnatal extant mammals and indicates the relationship of Meckel's cartilage with the middle ear in early mammals. The evidence shows that brain expansion may not be the initial factor that caused the separation of postdentary bones from the dentary as middle ear ossicles during mammalian evolution. The failure of the dentary to seize reduced postdentary elements during ontogeny of early mammals is postulated as an alternative mechanism for the separation. Modifications of both feeding and hearing apparatuses in early mammals may have led to the development of the definitive mammalian middle ear.     

利用SSR分子标记技术揭示"硬粒小麦-节节麦"人工合成六倍体小麦的遗传差异

为引入小麦近缘属种的优良基因和遗传变异、扩宽普通小麦的遗传基础,本文选用36对小麦A,B和D基因组的微卫星引物,对135份人工合成六倍体小麦的遗传多样性进行了评价。36对引物共检测到193个等位变异,每个位点等位变异数在2~14个之间,平均每个位点检测到5.36个等位变异;A,B和D 3个基因组检测到的等位变异数D>A>B,遗传多样性指数D>A>B。综合平均遗传丰富度和香浓指数两个指标分析结果表明,人工合成六倍体小麦第1和6同源群遗传多样性水平较高,第4和7同源群遗传多样性水平较低;21条染色体中,6D和2D染色体的遗传多样性最高,7D和4B染色体的遗传多样性最低。135份人工合成六倍体小麦遗传相似系数在0.36~0.85之间,平均遗传相似系数A>B>D基因组。人工合成六倍体小麦变异类型丰富,是改良普通小麦的重要基因资源。