贵州省野生火棘果营养成分与气候因子相关性分析

野生火棘在贵州省的资源分布广泛，由于省内各地区气候因子的不同，导致野生火棘果实的营养性成分存在差异。为探究贵州省野生火棘果的营养性成分差异，明确影响营养成分积累的气候因子，筛选出适宜生长区域，采用硫酸-苯酚法、全自动凯氏定氮仪、索氏提取法和福林-酚比色法对火棘果粗多糖、总蛋白、总脂肪和总多酚含量进行测定，并进行差异性分析、主成分分析和聚类分析；同时结合气候因子，进行灰色关联度的相关性分析。结果显示，不同产地之间4种营养成分含量存在明显差异，可将10个不同产地火棘分成3大类；灰色关联度分析表明，相对湿度是影响贵州野生火棘果营养成分含量的主要影响因子；降低相对湿度利于火棘果中营养性成分的积累。     

Expression of the Tobacco Ext 1.4 Extensin Gene Upon Mechanical Constraint and Localization of Regulatory Regions

Abstract: The regulation of the Ext 1.4 gene encoding a tobacco ( Nicotiana tabacum L.) extensin was studied in response to mechanical constraints. Transgenic plants carrying chimeric Ext 1.4 promoter/GUS (β-glucuronidase)/ nos terminator or Ext 1.4 3'-end constructs were obtained. Expression of gene fusions was found in tissues where mechanical stresses occur, e.g., during germination, as well as in root and stem tissues. Chimeric genes were successively and transiently expressed in different tissues during germination, i.e., at the tip of the root and then in the hypocotyl, during their growth through the seed coat. Moreover, they were expressed in cortical cells surrounding the emergence of adventitious and lateral roots and developmentally-regulated in nodes. The expression of Ext 1.4 could be induced by imposing mechanical constraints due to curving of either the stems or roots. Expression then occurred in cells where it does not normally occur, i.e., in cortical cells of internodes and in the distal piliferous zone of roots. Accumulation of RNAs occurs several days after the start of the constraint. Promoter regions involved in regulation of expression of Ext 1.4 in stems, roots, and in seedlings upon mechanical constraint could be localized. Moreover, the 3' non-coding region was shown to modulate expression in roots. These results suggest that the regulation of Ext 1.4 following mechanical stress is dependent on both tissue-specific and mechanical-responsive elements.     

Swimming performance of silver eels is severely impaired by the swim-bladder parasite Anguillicola crassus

Infection with the swim-bladder parasite Anguillicola crassus is suggested as one of the principal causes of the collapse of the European eel population. This nematode has been introduced in Europe from Asia in the 80s and parasitized in a short time Anguilla eel species in different geographical regions across the globe. The parasites drain energy due to their sanguivorous feeding and they cause mechanical damage on the swim-bladder wall. These two effects are hypothesized to impair the spawning migration of the European eel. In this study, we have investigated both effects on swimming performance. We hypothesized that parasitic sanguivorous activities - related to parasite weight - reduce swimming endurance, while mechanical damage of the swim-bladder impairs buoyancy control. Eighty eels suffering various degrees of infection were introduced in swim-tunnels and subjected to a swimming fitness test. The relation between A. crassus infection and swimming efficiency was measured for large female silver eels swimming at various speeds. Infected eels had lower cruising speeds and a higher cost of transport. Eels without parasites, but with a damaged swim-bladder showed similar effects. Almost half of the eels that contained damaged swim-bladders (43%) stopped swimming at low aerobic swimming speeds (< 0.7 m/s). Simulated migration trials in a recent related study have confirmed that eels with a high parasite level or with damaged swim-bladder show early migration failure (< 1000-km). Reduced swimming performance appears to be associated with swim-bladder dysfunction. As we found that especially silver eels have much higher infection levels than yellow eels, it is concluded that migrating silver eels with severely infected or damaged swim-bladders are unable to reach the spawning grounds.     

Survival and Cause-Specific Mortality of Neonatal Mule Deer Fawns,North-Central New Mexico

Abstract: Because of significant declines in mule deer (Odocoileus hemionus) populations across New Mexico, USA, we investigated survival of fawns in north-central New Mexico, USA. We captured 19 fawns, 34 fawns, and 47 fawns in 2002, 2003, and 2004, respectively, and used fawn morphological measurements, habitat characteristics, and adult female (hereafter “female”) condition to model preweaning fawn survival. Survival was 0.0, 0.12, 0.52 for 2002, 2003, and 2004, respectively, and was related to birth mass (χ₁² = 9.5, P = 0.002), birth date (χ₁²= 8.4, P = 0.004), litter size (χ₂² = 9.4, P = 0.009), female body fat (χ₁² = 40.9, P < 0.001), annual precipitation (χ₁² = 35.0, P < 0.001), summer precipitation (χ₁²= 37.5, P < 0.001), and winter precipitation (χ₁² = 32.0, P < 0.001). Total ingesta-free body fat of females (β = 3.01, SE = 0.75; odds ratio = 20.19, 95% CI = 4.64-87.91) and birth mass of fawns (β = 1.188, SE = 0.428; odds ratio = 3.38, 95% CI = 1.42-7.59) were the best predictors of survival of individual fawns, although few of the logistic models differed in model selection criteria. Fawn survival in north-central New Mexico was driven by an interaction of total and seasonal precipitation and its effect on plant production, consequential effects on female nutrition, and ultimately, fawn birth attributes. Habitat conditions were so poor throughout north-central New Mexico during 2002 and 2003 (and likely during other drought yr) that, based upon birth attributes, few fawns could have survived regardless of proximate causes of mortality. In 2004, precipitation enhanced security cover, maternal body condition, birth attributes and, thus, survival of fawns. However, more habitat enhancements are needed to improve the nutritional quality of mule deer habitats in north-central New Mexico and further enhance maternal and fawn condition to recover mule deer populations in this region.     

灵芝液体发酵条件的优化研究

通过单因素和正交试验,优化灵芝5760深层培养的营养需求与环境条件对灵芝菌丝体生物量及次生代谢产物发酵液多糖的作用。结果表明,适宜灵芝液体菌种培养和液体发酵的培养基配方为麦麸粉5%,黄豆饼粉3%,KH2PO40.10%,MgSO40.09%;适宜的环境条件为初始pH5.5,装液量32%,生物量最大时为第8～9d;适宜接种的种龄为6d,接种量为10%;发酵周期6d,搅拌转速150r/min,消沫剂添加量可为0.20%。从硒对灵芝5760菌丝体生长及深层发酵生物量的影响,灵芝5760富硒培养适宜浓度为100μg/mL;从加硒时间对生物量的作用,在菌龄适宜时期加入即第1d。     

Unity in diversity: Lessons from macaque societies

The macaque radiation is as old as the hominin radiation, approximately 7 million years. After Homo, Macaca has the widest geographical range among primates, and both of these genera are present in tropical and temperate regions as well. Whereas the single extant representative of the genus Homo diverged through processes of cultural diversification, extant species of macaques emerged through processes of evolutionary diversification. Macaque societies are characterized by profound unity and great diversity, and can best be described as variations on the same theme. To understand macaque variation and adaptation, we must take into account the processes that insure the persistence of their societies across generations and environments.     

Unconstrained cranial evolution in Neandertals and modern humans compared to common chimpanzees

A variety of lines of evidence support the idea that neutral evolutionary processes (genetic drift, mutation) have been important in generating cranial differences between Neandertals and modern humans. But how do Neandertals and modern humans compare with other species? And how do these comparisons illuminate the evolutionary processes underlying cranial diversification? To address these questions, we used 27 standard cranial measurements collected on 2524 recent modern humans, 20 Neandertals and 237 common chimpanzees to estimate split times between Neandertals and modern humans, and between Pan troglodytes verus and two other subspecies of common chimpanzee. Consistent with a neutral divergence, the Neandertal versus modern human split-time estimates based on cranial measurements are similar to those based on DNA sequences. By contrast, the common chimpanzee cranial estimates are much lower than DNA-sequence estimates. Apparently, cranial evolution has been unconstrained in Neandertals and modern humans compared with common chimpanzees. Based on these and additional analyses, it appears that cranial differentiation in common chimpanzees has been restricted by stabilizing natural selection. Alternatively, this restriction could be due to genetic and/or developmental constraints on the amount of within-group variance (relative to effective population size) available for genetic drift to act on.     

Peptide folding driven by Van der Waals interactions

Contrary to the widespread view that hydrogen bonding and its entropy effect play a dominant role in protein folding, folding into helical and hairpin-like structures is observed in molecular dynamics (MD) simulations without hydrogen bonding in the peptide-solvent system. In the widely used point charge model, hydrogen bonding is calculated as part of the interaction between atomic partial charges. It is removed from these simulations by setting atomic charges of the peptide and water to zero. Because of the structural difference between the peptide and water, van der Waals (VDW) interactions favor peptide intramolecular interactions and are a major contributing factor to the structural compactness. These compact structures are amino acid sequence dependent and closely resemble standard secondary structures, as a consequence of VDW interactions and covalent bonding constraints. Hydrogen bonding is a short range interaction and it locks the approximate structure into the specific secondary structure when it is included in the simulation. In contrast to standard molecular simulations where the total energy is dominated by charge-charge interactions, these simulation results will give us a new view of the folding mechanism.