Current Location:home > Browse


Your conditions: Biology(4,064)

1. chinaXiv:201906.00025 [pdf]

The tetrapod fauna of the upper Permian Naobaogou Formation of China— 4. the diversity of dicynodonts

Subjects: Biology >> Zoology

The Permian dicynodont records were previously rare in North China, but many dicynodont specimens have been collected from the Naobaogou Formation in Daqingshan area, Nei Mongol since 2009. Among these specimens, seven morphotypes have been identified, and they may represent seven different species: two of them are closely related to Daqingshanodon limbus, three or four are closely related to Jimusaria sinkianensis, and one may be closely related to Turfanodon. This study shows the dicynodonts also have a high diversity at the species level in North China.

submitted time 2019-06-11 From cooperative journals:《古脊椎动物学报》 Hits20Downloads8 Comment 0

2. chinaXiv:201906.00026 [pdf]

Molecular clock dating using MrBayes

Subjects: Biology >> Zoology

This paper provides an overview and a protocol of molecular clock dating using MrBayes. Two modern approaches, total-evidence dating and node dating, are demonstrated using a truncated dataset of Hymenoptera with molecular sequences and morphological characters. The similarity and difference of the two methods are compared and discussed. Besides, a non-clock analysis is performed on the same dataset to compare with the molecular clock dating analyses.

submitted time 2019-06-11 From cooperative journals:《古脊椎动物学报》 Hits16Downloads5 Comment 0

3. chinaXiv:201906.00027 [pdf]

Metatarsal II osteohistology of Xixianykus zhangi (Theropoda: Alvarezsauria) and its implications for the development of the arctometatarsalian pes

QIN Zi-Chuan; ZHAO Qi; XU Xing
Subjects: Biology >> Zoology

The late-branching alvarezsaurian Xixianykus zhangi is among the smallest known non-avialan theropods. With great similarity to its close relatives, it is highly cursorial as indicated by proportionally long lower segments of the hindlimbs and the presence of an arctometatarsalian pes–a highly modified structure that has been suggested to improve cursorial capability in theropods. Here we describe the osteohistology of the metatarsal II of the holotype of X. zhangi (XMDFEC V 0011). Two rarely reported histological features, radial vascular canals and Sharpey’s fibers, are presented in this study. We suggest that both features are related to the development of the arctometatarsalian pes; however, further investigations of metatarsal osteohistology in theropods are required for the validation of our interpretation.

submitted time 2019-06-11 From cooperative journals:《古脊椎动物学报》 Hits18Downloads7 Comment 0

4. chinaXiv:201906.00028 [pdf]

Cladistic approach on chronological relationship of the Pleistocene mammalian faunas from China

DONG Wei; LIU Wen-Hui; BAI Wei-Peng
Subjects: Biology >> Zoology

There are many localities yielding the Pleistocene mammalian faunas in China. It offers excellent material for the study of mammalian evolution, biochronology,paleoecology,paleoenvironment, paleozoogeography, etc. Faunal assemblage characters and taxonomic extinction rates were widely used for determining the faunal ages in biochronology. Faunal binary similarity coefficients sequenced according to Brainerd-Robinson’s rule and antiquity coefficients were further developed methods in biochronology for dating the faunal ages. The faunal binary similarity coefficients are based on the presence or absence of a taxon in a fauna. It is similar to the presence or absence of a character of a species in cladistic analyses for phylogeny, and all faunas have a special ancestor-descendant relationship. The present work is an attempt to find the relationship of the faunas with cladistic methods by selecting three groups of faunas sequenced by faunal binary similarity coefficients according to Brainerd-Robinson’s rule and antiquity coefficients, to compare the results with different methods, and then to estimate the ages of the faunas not yet dated by physical or chemical methods. The estimations are as follow: Gulongshan in Dalian, Liaoning Province: 16–20 ka; Shanchengzi at Benxi, Liaoning Province: 20–30 ka; Hualongdong at Dongzhi Man site, Anhui Province: 150–400 ka; Xinghuashan at Nanzhao Man site, Henan Province: 150–400 ka; Donghe at Luonan Man site, Shaanxi Province: 500–700 ka; Bailongdong at Yunxi Man site, Hubei Province: 500–850 ka; Meipu at Yunxian, Hubei Province: 500–850 ka; Mohui at Tiandong Man site, Guangxi Autonomous Region: 1.2–1.8 Ma; Juyuandong at Liucheng, Guangxi Autonomous Region: 1.2–1.5 Ma; Chutoulang at Chifeng, Nei Mongol Autonomous Region: 1.6–1.9 Ma; Renzidong at Fanchang, Anhui Province: 1.9–2.4 Ma.

submitted time 2019-06-11 From cooperative journals:《古脊椎动物学报》 Hits20Downloads7 Comment 0

5. chinaXiv:201905.00051 [pdf]


徐硕; 卢文玉
Subjects: Biology >> Bioengineering


submitted time 2019-05-06 Hits2413Downloads83 Comment 0

6. chinaXiv:201904.00094 [pdf]


王菲; 胡春辉; 于浩
Subjects: Biology >> Bioengineering

恶臭假单胞菌(Pseudomonas putida)KT2440中的6-羟基烟酸(6HNA)3-单加氧酶(NicC)是烟酸代谢过程中的关键酶。NicC通过在吡啶环上加羟基对吡啶环进行了活化,从而使得吡啶环可在双加氧酶催化下开环最终被完全降解。本研究通过去除NicC的N端稀有密码子增加了NicC的表达量,进一步利用Ni-Sepharose重力柱对NicC进行了纯化。通过实验发现,NicC的最适反应温度为30℃-40℃,最适反应pH为8.0。Cd2+离子对于NicC的酶活有明显的抑制作用。当NADH的浓度为0.25 mM的时候,底物6HNA所对应的NicC的最大酶活为14.1 U/mg,Km值为51.8 μM;当6HNA的浓度为0.25 mM的时候,底物NADH所对应的NicC的最大酶活为10.79 U/mg,Km值为15.0 μM。通过HPLC和LC-MS分析表明,NicC可以在NADH和氧气的参与下催化6HNA转化生成2,5-二羟基吡啶(2,5-DHP)和甲酸,另外可以将对羟基苯甲酸转化生成对苯二酚。同位素标记实验表明产物2,5-DHP中的氧原子来源于参与反应的氧气。该研究为研究吡啶类化合物微生物代谢提供了理论基础。

submitted time 2019-04-21 From cooperative journals:《中国生物工程杂志》 Hits2889Downloads137 Comment 0

7. chinaXiv:201904.00073 [pdf]


李雄; Supriyo Basak; 周睿; 张卫哲; 付瑶; 周新茂; 施超; 郗厚诚; 杨永平
Subjects: Biology >> Ecology


submitted time 2019-03-30 Hits2997Downloads149 Comment 0

8. chinaXiv:201903.00232 [pdf]

Conversion of cropland into agroforestry land versus naturally-restored grassland alters soil macro-faunal diversity and trophic structure in the semi-arid agro-pasture zone of northern China

LIU Rentao
Subjects: Biology >> Ecology

Restoration of cropland (termed 'Farm') after abandonment including shrubs (termed 'Shrub'), trees (termed 'Tree') and natural grassland (termed 'Grass') has become a routine process aimed to improve land productivity and control desertification. During this restoration process, soil macro-faunal diversity, and trophic structure were investigated at four types of sites (Farm, Shrub, Tree, and Grass) during growing season in the semi-arid agro-pasture zone of northern China. Results indicated that the Staphylinidae family was found to dominate at the Grass, Shrub, and Tree sites, whiles larval Pyralidae individuals were found at the Grass site only. The density of the omnivores (i.e., Formicidae family) was significantly (P<0.05) greater at the Grass site than at the Tree and Farm sites. The total density and richness of predator and phytophages were found to be markedly (P<0.05) greater at the Grass site than at the Farm site. Meanwhile, we found the taxon richness of predators was significantly (P<0.05) higher at the Shrub site than at the Farm and Tree sites. Compared with the Farm and afforested Shrub/Tree sites, the Grass site had greater density, taxon richness, and Shannon index (P<0.05). In conclusion, natural restoration of abandoned croplands toward grassland was an effective strategy relative to artificial afforestation for improvement of soil biological diversity. Moreover, planting shrub is a preferable measure in abandoned croplands for land development in the semi-arid agro-pasture zone of northern China.

submitted time 2019-03-28 From cooperative journals:《Journal of Arid Land》 Hits5086Downloads2368 Comment 0

9. chinaXiv:201903.00233 [pdf]

Exogenously applied glycinebetaine induced alteration in some key physio-biochemical attributes and plant anatomical features in water stressed oat (Avena sativa L.) plants

Subjects: Biology >> Physiology

Although exogenous application of glycinebetaine (GB) is widely reported to regulate a myriad of physio-biochemical attributes in plants under stressful environments including drought stress, there is little information available in the literature on how and up to what extent GB can induce changes in anatomical features in water starved plants. Thus, the present research work was conducted to assess the GB-induced changes in growth, physio-biochemical, and anatomical characteristics in two cultivars (CK-1 and F-411) of oat (Avena sativa L.) under limited water supply. After exposure to water stress, a considerable reduction was observed in plant growth in terms of lengths and weights of shoot and roots, leaf mesophyll thickness, leaf midrib thickness, root cortex thickness, root diameter, stem diameter, stem phloem area, and stem vascular bundle area in both oat cultivars. However, water stress resulted in a significant increase in leaf total phenolics, hydrogen peroxide (H2O2), ascorbic acid (AsA), GB contents, activities of enzymes (CAT, SOD and POD), total soluble proteins, leaf epidermis (abaxial and adaxial) thickness, bulliform cell area, sclerenchyma thickness, root endodermis and epidermis thickness, root metaxylem area, stem metaxylem area and stem sclerenchyma thickness in both oat cultivars. Foliar-applied 100 mM GB suppressed H2O2 contents, while improved growth attributes, free proline and GB contents, activity of SOD enzyme, leaf abaxial epidermis thickness, leaf bulliform cell area, leaf midrib thickness, leaf sclerenchyma thickness, root cortex thickness, root endodermis, epidermis thickness, root stele diameter, stem diameter, stem epidermis thickness, stem metaxylem area, and stem phloem and vascular bundle area in both oat cultivars. For both oat cultivars, CK-1 was superior to F-411 in leaf abaxial epidermis thickness, leaf mesophyll, leaf sclerenchyma, root metaxylem area, stem diameter, stem epidermis, sclerenchyma thickness, stem metaxylem area, and stem vascular bundle area. Overall, both oat cultivars showed inconsistent behavior to water stress and foliar-applied GB in terms of different physio-biochemical attributes, however, CK-1 was superior to F-411 in a number of anatomical features of leaf, root, and stem.

submitted time 2019-03-28 From cooperative journals:《Journal of Arid Land》 Hits1631Downloads189 Comment 0

10. chinaXiv:201903.00235 [pdf]

Impact of air drought on photosynthesis efficiency of the Siberian crabapple (Malus baccata L. Borkh.) in the forest-steppe zone of Transbaikalia, Russia

Subjects: Biology >> Botany

The adaption of photosynthesis, being a key metabolic process, plays an important role in plant resistance to air drought. In this study, the Siberian crabapple (Malus baccata L. Borkh.) in the forest-steppe zone of Transbaikalia region, Russia, was subjected to air drought stress and its photosynthesis characteristics were analyzed. The results show that air drought and sufficient soil moisture supply lead to the decrease in the total chlorophyll (Chl) content, while the ratio of Chls to carotenoids is constant in the Siberian crabapple tree. The function of photosystem II (PS-II) in the crabapple trees is characterized by a decrease in the fraction of absorbed light energy spent on the photochemical work and an increase in the proportion of non-photosynthetic thermal quenching. These changes indicate the photosynthetic down-regulation that acts as a universal photoprotective mechanism. During the midday hours, the combination of high air temperature and low air humidity leads to the decrease in the maximum photochemical quantum yield of photosystem II (Fv/Fm) and the efficiency of photosynthesis (PABS). The parameters of leaf gas exchange show the significant differences in these values between the control and experimental variants. During the morning hours, the Siberian crabapple, growing in the Irkutsk City, assimilates carbon dioxide more intensively. Due to the higher air humidity, the stomata are kept open and the necessary amount of carbon dioxide entries the sites of carboxylation. The low air humidity combined with wind in the experimental variants leads to the unreasonably high water loss in the crabapple leaves by more than 27% as compared to the control variant (Irkutsk City). However, water use efficiency in the morning hours increases during plant photosynthetic processes, i.e., 42% higher than that of control. This, apparently, is a reflection of the adaptation processes of the Siberian crabapple to the air drought and parching wind.

submitted time 2019-03-28 From cooperative journals:《Journal of Arid Land》 Hits1596Downloads203 Comment 0

12345678910  Last  Go  [407 Pages/ 4064 Totals]