Migratory route of Strongyloides venezuelensis in Lewis rats: Comparison of histological analyses and PCR

Strongyloides venezuelensis is a parasitic nematode that has been used as a model to study human and animal strongyloidiasis. In this study, we compared the sensitivity between traditional methodologies and PCR assay to characterize the dynamics of S. venezuelensis infection and its migration route in Lewis rats subcutaneously infected with 4000 L3. The dynamics of the infection was determined by counting the number of eggs and by detecting parasite deoxyribonucleic acid in faeces samples. Both techniques similarly detected the infection at day 6 after larvae inoculation. However, PCR performed with the genus primer showed higher sensitivity during the recovery phase. Histological analysis and PCR assay were then used to follow parasite tissue migration. S. venezuelensis migration route included the muscular fibers below the skin, the pulmonary alveoli and the small intestine vilosities. The sensitivity of these two techniques to detect parasite’s presence in these tissues was statistically similar.     

The effects of feeding time and time-restricted feeding on the fattening traits of White Roman geese

This study comprises two trials that investigated the effects of feeding time and time-restricted feeding on the fattening traits and plasma metabolite levels of White Roman geese. In Trial I, 24 geese aged 8 weeks of each sex were allowed free access to a fattening diet for 1 h either in the morning (morning-feeding group) or afternoon (afternoon-feeding group). At 12 weeks of age, blood samples were collected hourly for 4 h, beginning 1 h after feeding to determine the plasma levels of glucose, triacylglycerols and uric acid. The results showed a lower (P<0.05) daily feed intake (DFI) and daily gain (DG) and higher (P<0.05) feed efficiency (FE) for the morning-feeding group compared with those of the afternoon-feeding group. In addition, the postprandial plasma levels of glucose, triacylglycerols and uric acid did not differ (P>0.05) between groups. In Trial II, 12 geese aged 8 weeks of each sex were randomly assigned to either the ad libitum feeding group (control group) or time-restricted feeding group (restricted group). The geese in the control group were fed a fattening diet ad libitum, whereas those in the restricted group were allowed access to the diet for 2 h every morning. All geese were killed at 13 weeks of age and their carcass traits were evaluated. The results showed a lower DFI and DG and higher FE for the restricted group compared with those of the control group (P<0.05). In addition, the restricted group exhibited lower visceral and abdominal fat and higher empty digestive tract and liver weights than those of the control group (P<0.05). The results showed that time-restricted feeding in the morning resulted in superior DG and FE compared with feeding in the afternoon. Moreover, time-restricted feeding implemented in the morning during the fattening period reduced DFI and increased FE in geese compared with ad libitum feeding.     

Swainson’s thrushes in migratory disposition exhibit reduced immune function

Evidence indicates that the immune system, which protects an organism from parasitic and pathogenic infections, is frequently suppressed when animals are engaged in activities involving strenuous exercise. We tested the hypothesis that birds reduce immune function during the migratory period in preparation for the anticipated heightened energetic demands of long flights. Swainson’s thrushes (Catharus ustulatus), captured in fall, were held in an indoor aviary until January, when migratory disposition was induced in half of the birds with an artificially prolonged daylength. Experimental birds became hyperphagic and deposited fat stores, and then displayed nocturnal activity (Zugunruhe) characteristic of the spring migratory period. Cell-mediated immunity was measured by intradermal injection of phytohemagglutinin in the wing patagium of both control and experimental birds. Birds exhibiting migratory restlessness had a reduced cell-mediated immune response compared to control birds. Our results suggest that birds are immunosuppressed during the migratory period. The suppression may be a nonadaptive response due to unrelated physiological processes, or it may be an adaptive response to the physiological demands associated with migration, such as high energetic demands and the negative consequences of a hyperactive immune system.     

Diet preferences for specific fatty acids and their effect on composition of fat reserves in migratory Red-eyed Vireos (Vireo olivaceous)

Fatty acid composition of body fat in birds often differs between bird species and between seasons, and changes in diet may be responsible for this variation. We tested two related hypotheses using Red-eyed Vireos, a long-distance migratory songbird: (1) birds prefer diets with certain fatty acids, and (2) fatty acid composition of the diet primarily determines the composition of lipid reserves. During paired-choice experiments, vireos preferred semi-synthetic diets with triolein (81% digestive extraction efficiency) over diets with tristearin (54% digestive extraction efficiency) and, in general, ate more when offered diets with unsaturated fats compared to saturated fats. These results demonstrate that vireos can discriminate between diets differing only in fatty acid composition and prefer diets with long-chain unsaturated fatty acids. When vireos were fed one of two diets for 1 month, the primary fatty acids in each diet also predominated in the tissues of birds fed each diet. However, some fatty acids that were absent in the diet occurred in bird tissues (e.g., 22:4, 22:5) suggesting that selective metabolism of fatty acids along with diet composition determine the fatty acid composition of lipid reserves in migratory birds.     

Three-dimensional collective cell motions in an acinus-like lumen

Collective cell migration is an essential process in embryo development, wound healing, inflammatory response, and cancer invasion. Although cell motions in two-dimensional (2D) monolayers have been studied previously, three-dimensional (3D) collective cell migration, which constantly occurs during embryogenesis such as the establishment of ducts and acini in vivo, remains elusive. In this paper, we develop a cell-based model incorporating cell mechanics and cell motility to address coherent cell motions in a spherical acinus-like lumen with different cell populations. It is found that the interplays between cell persistence, random fluctuation, and geometrical confinement may engender rich and novel migratory modes. In a 3D spherical lumen, two cells may undergo stripe-like or cross-circular coherent rotations, whereas multiple cells can form dynamic twisting or circulating bands, leaving sparse cells at the center or even a hollow cavity in the cell aggregate. The cell density is found to profoundly influence the collective cell migration modes. Our model can reproduce the fundamental features observed in experiments and highlight the role of mechanics in steering 3D collective cell dynamics during mammary acinar morphogenesis.     

Stable individual profiles of daily timing of migratory restlessness in European quail

Temporal characteristics of migratory behavior in birds are usually studied at the species and population levels, and rarely at the individual level. Variations among species and populations of the seasonal onset of migratory behavior have been widely investigated, but very little is known about its daily organization or whether birds are conservative in their behavior. The determination of intra- and inter-individual variability is important for the study of genetic variations and can reveal the existence of different adaptation capacities within populations. This laboratory study analyzed intra- and inter-individual variability of daily initiation and time course of nocturnal restlessness in partial-migrant European quail (Coturnix coturnix coturnix). Thirty-five quail were selected randomly from a captive stock, and their spring activity was recorded under natural daylenghs. Eighteen of the thirty-five quail presented behavioral profiles of migrant birds. Migrant birds initiated their nocturnal activity punctually, and the time courses of the nocturnal activity of 88% of them revealed intra-individual stability over six consecutive nights. All birds initiated their nocturnal activity after sunset and civil twilight, and they were more active at the beginning than the middle or end of the night, suggesting that their drive to migrate could be synchronized with particular skylight conditions. For the first time, stable individual profiles in the daily time course of migratory restlessness are shown. These results support previous findings concerning biological rhythms of quail and raise questions concerning the timing of migratory behavior.     

新疆哈密地区粉红椋鸟繁殖行为及招引对策的初步研究

粉红椋鸟(Sturnus roseus)是一种长距离迁徙鸟类,新疆是其在中国境内的繁殖区。本研究于2009年5～7月粉红椋鸟繁殖期内,在哈密巴里坤山前草原地带对其繁殖行为进行了系统的野外观察。结果表明,①粉红椋鸟多选择隐蔽的场所营巢,巢内、外径分别为(8.08±0.38)cm和(25.25±2.82)cm,巢高、深分别为(4.55±1.65)cm和(63.00±35.34)cm,n=8;②粉红椋鸟一年产一窝,窝卵数平均为(4.25±0.71)枚(n=8);孵化率为94.12%,雏鸟成活率为88.24%(n=34);③粉红椋鸟每日不同时段育雏次数差异极显著(P0.01),每日6:30～7:30、10:30～12:30时出现育雏高峰,平均(7.6±1.1)min育雏一次;④粉红椋鸟雏鸟生长发育呈S型曲线变化。研究结果可为提高粉红椋鸟人工招引率提供理论指导。     

飞蝗总DNA的抽提及其RAPD分析条件的摸索

通过试验寻求得到一种快速、简便抽提飞蝗（Ｌocusta sp.)总DNA方法,使每头雄性和雌性成虫分别可以得以５０和１００μg的总ＤＮＡ。所得到的总ＤＮＡ ＯＤ２６０／ＯＤ２８０为１．５－２．２,分子量４５kb。为了获得高分子量的ＤＮＡ产品,使ＲＰＡＤ结果具重复性,酚氯仿抽提后的ＤＮＡ沉淀用灭菌Ｔip头挑出,而不用离心收集。对各种分析条件如摸板、Ｔaq酶、dNTP及引物的浓度、不同的ＰＣＲ仪、反应管进行了比较试验,发现在一定的范围内,它们对ＲＡＰＤ结果影响。用优化的试验条件对我国３个飞蝗亚种５个地理种群进行ＲＡＰＤ分析。结果在３个亚种ＵＰＧＭＡ聚类图中,东亚飞蝗和西藏飞蝗珠２个种群以１００％Ｂootstrap分别聚类在一起,亚洲飞蝗与东亚飞蝗的２个种群以６６％的Ｂootstrap聚类在一起,在３个亚种所有个体的ＵＰＧＭＡ聚类图中,亚种内的所有个体都聚类在一起,各自形成独立分支,说明３个飞蝗亚种有明显的区别。西藏飞蝗的２个种群之间,群居型与散居型东亚飞蝗之间在聚类图中混合聚类,说明它们之间存在基因交流。     

光照与飞蝗卵耐寒性的关系

用热电偶法测定长光照(L：D=14：10)和短光照(L：D=10：14)条件下饲养的飞蝗所产卵的过冷却点;并对长、短光照组分别设置5个温度(0、-5、-10、-15和-20℃)处理,每一温度又设置5个时间(6h,1、3、5和10d)处理,然后检查其28℃的孵化数,以此计算低温存活率和半致死温度。长、短光照组卵的过冷却点没有差异;两种光照条件下的低温存活率随着卵处理温度的降低和时间的延长而下降,在-5和-10℃时短光照组的低温存活率显著高于长光照组;卵的半致死温度随低温处理时间的延长而升高,短光照组的半致死温度明显低于长光照组。接受短光照的飞蝗母本能产出耐寒性较高的卵,暗示秋天所产的卵能更成功地越冬。     

混合植物油替代鱼油对中华绒螯蟹成体雄蟹常规成分和脂肪酸组成的影响

为研究育肥饲料中混合植物油替代鱼油对中华绒螯蟹(Eriocheir sinensis)成体雄蟹常规成分和脂肪酸组成的影响,采用豆油和菜籽油混合物替代鱼油制成5种不同鱼油替代水平(0%、25%、50%、75%和100%)的等氮等脂育肥饲料(分别记为1#~5#饲料组)饲喂雄蟹,测定5组雄蟹肝胰腺、肌肉和性腺中的常规成分和脂肪酸组成,并对实验数据进行方差分析。结果显示:(1)饲料1#组性腺灰分含量显著高于饲料4#和5#组(P0.05),但各组性腺中的水分、总脂和蛋白含量均无显著差异(P0.05);饲料1#组肝胰腺中的水分和灰分最高,但其总脂含量低于其他组,各组肝胰腺的蛋白含量无显著差异(P0.05);除1#饲料组外,肌肉中的总脂和灰分含量随鱼油替代水平的升高而显著上升(P0.05),而水分和蛋白含量均无显著差异(P0.05)。(2)各饲料组精巢中总饱和脂肪酸(∑SFA)、总多不饱和脂肪酸(∑PUFA)和总高度不饱和脂肪酸(∑HUFA)含量无显著差异(P0.05),其总n-6多不饱和脂肪酸(∑n-6PUFA)含量随鱼油替代水平升高而升高,而总n-3多不饱和脂肪酸(∑n-3PUFA)含量和∑n-3PUFA/∑n-6PUFA比值呈显著下降趋势(P0.05)。(3)肝胰腺中∑n-3PUFA和∑HUFA含量具有显著的组间差异,且均以饲料3#组最高。但各组的∑PUFA和∑n-6PUFA含量差异并不显著(P0.05)。(4)肌肉中大部分脂肪酸组成无显著差异,仅∑n-6PUFA含量随鱼油替代水平升高而升高。综上,中华绒螯蟹育肥饲料中植物油(豆油与菜籽油含量为1︰1)替代鱼油对成体雄蟹可食组织中水分和蛋白含量并无显著影响,但会对其脂肪酸组成造成显著的影响,50%的鱼油替代水平有利于雄蟹肝胰腺和肌肉中的脂肪沉积。