休眠卵孵化对策与食物浓度对萼花臂尾轮虫(Brachionus calyciflorus)两品系干雌体种群增长的影响

周期性孤雌繁殖的轮虫靠休眠卵度过不良环境,等环境适宜时休眠卵孵化出干雌体,再次通过孤雌繁殖建立种群。通常休眠卵要经历一段休眠期再孵化,但也有些休眠卵生成后很快孵化,称为早孵化现象。有关休眠卵不同孵化对策如何影响其干雌体克隆种群的增长,目前尚不清楚。分别观测了萼花臂尾轮虫（Brachionus calyciflorus）的两个品系H1（窄温度生态位）和D1（宽温度生态位）的休眠卵在不同孵化对策和不同食物浓度下所生产的干雌体克隆群的种群增长差异。孵化对策包括早孵化（early hatching,EH）和晚孵化（late hatching,LH）;食物浓度包括高食物浓度（high food concentration,HF：2×10⁶个细胞/mL）和低食物浓度（low food concentration,LF：5×10⁵个细胞/mL）,每个品系下各设置4个实验组（LH-HF、LH-LF、EH-HF、EH-LF）,每组10个重复。结果发现,对D1品系来说：孵化对策和食物浓度对最大种群数量具有显著的综合影响（P=0.002）,但两因素间不存在交互作用（P=0.911）;早孵化的干雌体种群在最大种群数量上显著高于晚孵化的干雌体种群（P=0.001）。对H1品系：孵化对策和食物浓度对最大种群数量综合影响显著（P<0.001）,且两个因素之间存在交互作用（P<0.001）;高食物浓度下,EH干雌体克隆群的最大种群数量显著低于LH干雌体克隆群（P<0.001）。高食物浓度下干雌体克隆群开始有性生殖的密度阈值,D1品系EH组显著高于LH组（P=0.041）;而H1品系EH组却显著低于LH组（P=0.022）。最高种群密度下,H1品系的有性生殖率在两种孵化对策之间存在显著差异（P=0.044）,EH种群的有性生殖率低于LH种群,而D品系却未见有性生殖率在不同孵化对策间存在明显差异。本研究结果显示休眠卵的孵化对策会影响其后代干雌体种群的增长特性,其影响的结果可能与种群的生境适应相关。     

Raman-based dynamic feeding strategies using real-time glucose concentration monitoring system during adalimumab producing CHO cell cultivation

The use of Process Analytical Technology tools coupled with chemometrics has been shown great potential for better understanding and control of mammalian cell cultivations through real-time process monitoring. In-line Raman spectroscopy was utilized to determine the glucose concentration of the complex bioreactor culture medium ensuring real-time information for our process control system. This work demonstrates a simple and fast method to achieve a robust partial least squares calibration model under laboratory conditions in an early phase of the development utilizing shake flask and bioreactor cultures. Two types of dynamic feeding strategies were accomplished where the multi-component feed medium additions were controlled manually and automatically based on the Raman monitored glucose concentration. The impact of these dynamic feedings was also investigated and compared to the traditional bolus feeding strategy on cellular metabolism, cell growth, productivity, and binding activity of the antibody product. Both manual and automated dynamic feeding strategies were successfully applied to maintain the glucose concentration within a narrower and lower concentration range. Thus, besides glucose, the glutamate was also limited at low level leading to reduced production of inhibitory metabolites, such as lactate and ammonia. Consequently, these feeding control strategies enabled to provide beneficial cultivation environment for the cells. In both experiments, higher cell growth and prolonged viable cell cultivation were achieved which in turn led to increased antibody product concentration compared to the reference bolus feeding cultivation.     

芽胞杆菌中重组蛋白分泌表达的优化策略及研究进展

芽胞杆菌属具有良好的蛋白表达和分泌能力,在工业酶的生产中被广泛应用,是理想的工业宿主菌,但实现蛋白分泌表达的普遍高效性还存在许多瓶颈。本文综述了芽胞杆菌的蛋白分泌表达策略,从启动子、信号肽、分泌途径、宿主和培养条件这5个方面总结了提高芽胞杆菌中分泌表达重组蛋白的方法,对芽胞杆菌高效生产工业酶有一定的参考价值,最后展望了优化芽胞杆菌分泌表达的研究方向,各种新型生物技术的发展必将推进芽胞杆菌在分泌表达领域有更深入的应用。     

Individual and sex‐related patterns of prolonged flights during both day and night by great reed warblers crossing the Mediterranean Sea and Sahara Desert

A wide variety of the barrier crossing strategies exist among migrating songbirds, ranging from strict nocturnal flights to non‐stop flights over a few days. We evaluate barrier crossing strategies in a nocturnally migrating songbird crossing the Mediterranean Sea and the Sahara Desert, the great reed warbler, exploring variation between the sexes and within individuals. We used data from 31 year‐round light‐level geolocators tracks from 26 individuals (13 males and 13 females), with four individuals tracked for 2–3.5 consecutive years. Almost all individuals (25 of 26) prolonged their flights into the day at least on one occasion. The mean duration of these prolonged flights was 19.9 h and did not differ between sexes or seasons. Fifteen birds performed non‐stop flights during more than one full day and night (≥ 24 h; mean = 31.9 h; max = 55 h) in autumn and/or spring, but these flights were generally too short to cross an entire barrier (such as the Sahara Desert) in one non‐stop flight. Patterns of prolonged flights showed considerable within‐individual variation in females between seasons (autumn versus spring) and in both males and females between years, suggesting high individual flexibility in migration strategy. Significantly more males than females performed prolonged flights during autumn migration, but not spring, possibly reflecting sex‐specific carry‐over effects. We conclude that great reed warblers have the ability to conduct prolonged continuous flights for up to several nights and days, which potentially would allow them to cross the Sahara Desert in one non‐stop flight. However, they typically use a mixed strategy of several nocturnal flights with intermittent stopovers in combination with 1–3 prolonged flights. Prolonged flights covered less than half (44%) of the total flight time across the barriers, and the diurnal parts of the flights covered only 18% of this time.     

华北低山丘陵区常用树种木质部解剖特征及水其力学抗旱性

木本植物木质部解剖特征与水分运输和干旱适应策略密切相关,但目前对华北低山丘陵区常用树种这方面的研究仍然不足。为研究这一地区植物木质部解剖特征与抗旱性的关系,研究以抗旱树种和非抗旱树种各5种为研究对象,通过测定与木质部横截面导管、薄壁组织相关的大量解剖学性状和非结构性碳浓度,比较两类树种木质部解剖特征的差异和解剖性状间的关联,以探究这些树种水力学的干旱适应策略差异。结果显示:1)10个树种的16个木质部性状均有较大变异性;2)两类树种间的平均导管直径和导管密度无显著差异,但抗旱树种导管壁厚度、最大导管直径、旁管薄壁组织比例和轴向薄壁组织比例以及非结构性碳(NSC)浓度显著大于非抗旱树种;3)抗旱树种的导管壁厚度与平均导管直径、最大导管直径和潜在最大导水率均呈显著正相关关系,最大导管直径与潜在最大导水率呈显著正相关关系,但非抗旱树种不存在这些关系。本研究抗旱树种同时具有较大的最大导管直径和较厚的导管壁,在保证较高的水分运输效率的同时又具备一定的抗栓塞能力,较多的旁管薄壁组织和NSC也为抗旱树种提供了更大的木质部水储存和栓塞修复能力。     

海拔梯度变化对武夷山黄山松林土壤磷组分和有效性的影响

土壤磷（P）是植物生长必需的养分元素,也是亚热带森林生产力的主要限制元素。目前,关于不同海拔土壤P组分和P有效性的变化规律尚无统一定论,其原因主要是忽略了植被类型变化导致的P组分和P有效性对海拔的响应更为复杂。因此,以武夷山不同海拔黄山松林为研究对象,通过测定土壤环境因素、理化性质、微生物生物量（SMB）、酸性磷酸单酯酶（ACP）和磷酸双酯酶（PD）活性以及土壤P组分,探究土壤P组分和P有效性的变化及其影响因素。结果表明,随海拔降低,速效P含量显著增加,而易分解P、中等易分解P、难利用P和总磷含量显著减少。冗余分析结果表明,微生物生物量磷和微生物生物量氮是影响土壤P组分和P有效性变化的关键因素。研究表明,随海拔降低,黄山松林土壤微生物通过提高ACP、PD活性和降低SMB含量的能量分配策略,促进更多较难分解P组分的矿化,从而提高速效P含量,以满足微生物对P的需求。因此,在低海拔地区,微生物通过能量分配策略获取更多有效P,可能有利于提高武夷山黄山松林土壤速效P的供应,但从长期来看,可能使P矿化速率提高和P损耗增加,导致P库的储备不足,不利于土壤P素养分的可持续供应。     

野生藏酋猴冬季食物组成及营养成分

觅食是获取营养物质和能量的重要途经。对于栖息在四季分明地区的灵长类动物而言,低温以及食物资源相对匮乏的冬季是其生存和生长发育的瓶颈期。本研究以安徽黄山的野生藏酋猴（Macaca thibetana）天湖山群为对象,于2019年11月至2020年1月采用瞬时扫描取样法（Instantaneous scan sampling）采集猴群觅食行为数据,并分析其冬季食物组成及食物中各化学成分含量对取食的影响。结果显示,野生藏酋猴在冬季共取食23科31属34种植物,主要包括壳斗科（Fagaceae,21.62%）、樟科（Lauraceae,17.57%）、蔷薇科（Rosaceae,8.11%）的植物,取食部位以叶片（66.22%）和果实（种子）（24.32%）为主。不同取食部位的水分、总糖、淀粉、脂肪、单宁等成分存在显著差异。其中,叶片的水分含量高于果实（种子）、茎和芽,茎和果实（种子）含有较高的总糖,果实（种子）的淀粉和脂肪含量最高,芽的单宁含量最高。此外,取食植物中的总糖含量高于非取食植物。结果表明,野生藏酋猴适应寒冷冬季与食物匮乏的觅食策略是对植物种类、植物部位及其主要营养成分的综合结果。     

Partial bivoltinism in a gregarious endoparasitoid: larval diapause as influenced by season and sharing a host

The yearly timing of the life cycle of a parasitoid is a key element of its life‐history strategy. I examine here factors influencing the expression of partial bivoltinism in Tetrastichus julis Walker (Hymenoptera: Eulophidae), a specialist parasitoid introduced to North America to attack its univoltine host, the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae). The varying tendency was assessed of individuals of this gregarious larval parasitoid to either emerge as adults in the same summer they mature, or to enter diapause to emerge the following year. Parasitized hosts were obtained by rearing cereal leaf beetles collected as mature larvae from grain fields in northern Utah (western USA) throughout the growing seasons in 2013 and 2014. Cocoons spun by these beetles were held to determine patterns over the spring and summer in the tendency of the parasitoid to forgo larval diapause. A high percentage (nearly 90% in 2013) of parasitoid individuals were found to forgo diapause and emerge in the same summer from earliest maturing hosts. This percentage rapidly declined to 20% or less of individuals forgoing diapause and emerging from cocoons as the summer advanced. The percentage of parasitoid individuals forgoing diapause increased significantly at a given time of season (early or late) as the number of conspecifics with which an individual shared a host larva increased. These results may reflect a trade‐off for individual parasitoids in which greater success in finding – and ovipositing in – host larvae the following spring vs. in summer, is countered by reduced survivorship in diapausing over the winter vs. emerging in the same summer in which the parasitoid matures. Expression of partial bivoltinism of T. julis, as affected strongly by both season and within‐host density, results in high rates of parasitism of cereal leaf beetles both early and late in the season.     

Individual and group characteristics affecting nest building in sea lamprey (Petromyzon marinus L. 1758)

Nest building relates to reproductive effort, sexual selection, intersexual conflict and cooperation and may be linked to individual phenotype and interindividual interactions. In particular, larger individuals having more energy reserves are expected to build more, larger nests, without having to trade intrasexual competition for cooperative nest building. Capture–mark–recapture and nest survey of sea lamprey (Petromyzon marinus L. 1758) were combined to assess the relationship between individuals and nesting activity on a spawning ground, throughout a breeding season, during which 202 nests were observed and 114 individuals were captured. On average, males and females stayed 8.33 ± 1.02 and 3.57 ± 1.04 days on the spawning ground, visited 2.26 ± 1.72 and 1.67 ± 1.17 nests and encountered 2.33 ± 2.13 mates for males and 2.29 ± 1.32 mates for females, respectively, and the number of mates encountered increased with the number of nests visited. Body size had no effect on the duration of presence on spawning ground, number of nests visited, number of individuals per nest and sex ratio on nest or nest volume. Bigger nests were found at the end of the season and were not necessarily built by more individuals. This work brings insights on the mating system and cooperative nest building in sea lamprey and may inform managers who want to estimate sea lamprey populations via nest surveys.