黑线毛足鼠能量策略的个体差异与权衡北大核心CSCD

为了应对由冬季低温与食物匮乏所带来的挑战,动物进化出了不同的能量策略,如迁徙、换毛、贮食、储脂和蛰眠等,但个体间可能存在差异,且不同策略之间可能存在一定的权衡。有研究者认为,黑线毛足鼠(Phodopus sungorus)的贮食和日蛰眠等能量策略之间可能存在权衡。本研究测定了低温短光[(10±2)℃,光照与黑暗之比L︰D为8︰16]及自由取食或限食条件下黑线毛足鼠的体重、摄食量、贮食量、食物摄取总量、基础代谢率、体核温度与活动性等7项指标的个体差异,并探讨摄食(包括贮食)、基础代谢率与蛰眠之间是否存在权衡,以推测黑线毛足鼠对低温与食物匮乏能量响应策略的个体差异产生的原因。结果显示,在低温短光、自由取食条件下,摄食量无性别差异,雄性个体的体重大于雌性个体,体核温度及活动性低于雌性个体。在限食阶段且低温短光情况下,出现了蛰眠个体,蛰眠个体在自由取食阶段的活动性高于非蛰眠个体,即活动性高的个体更可能产生蛰眠。蛰眠个体与非蛰眠个体的基础代谢率无差异。但是,在蛰眠个体中,基础代谢率与蛰眠频率负相关,活动性与蛰眠持续时间负相关。在非蛰眠个体中,限食程度升高后活动量显著增加。此外,虽然与贮食和蛰眠可能存在负相关关系的预测相符,贮食个体均不蛰眠,但是动物是否贮食、贮食量以及食物摄取总量(包括贮食量)均与蛰眠无显著相关。本研究表明,能量对策之间的权衡并非发生于贮食和蛰眠之间,而是存在于基础代谢率、活动性与蛰眠之间,不蛰眠的个体倾向于降低活动性以节约能量,而基础代谢率和自由取食阶段活动性高的蛰眠个体则拥有更低的蛰眠表达。     

Energy Allocation in Mammalian Reproduction

SYNOPSIS. On behavioral, hormonal, and physiological grounds,mammalian reproduction can be compartmentalized into the followingcontinuous sequence of events: mating (courtship, estrous),gestation, parturition, lactation, post-lactational parentalcare, and maternal recovery. We point out that comparing therelative allocation of energy for these events across mammalsis difficult because of life history variability (e.g., littersize, birth weight), allometry, phylogeny, and individual variation.We review the empirical and theoretical literature on each ofthese events with respect to: different methodologies in measuringenergy use;broad patterns of energy consumption across diversemammalian taxa; and, identification of particular reproductivecharacteristics (e.g., birthing, parental care) which may becostly but have yet to receive energetic measurements. Althoughmost studies have consideredgestation and lactation the criticalreproductive events for energy expenditure, variation in theseevents is substantial and almost certainly is a function ofrelative allocation of time togestation vs. lactation as wellas the presumed energetic costs of mating, birthing and parentalcare. In addition, repeated observations show that behavioralcompensation is an extremely important strategy for minimizingenergy requirements during reproduction. From this review, weargue that more complete analyses will come from (1) incorporatingenergetic measurements in studies of mammalian behavior and(2) including mechanisms of behavioral compensation into physiologicalstudies.     

Reproductive Performance Among Sows Group-Housed During Late Lactation

Four farms (540 sows) that group-housed sows from 2 weeks of lactation until weaning (G-farms) and 3 farms (300 sows) — used as controls — that kept the sows individually penned throughout the 5- to 6-week-long lactation period (C-farms) were compared in terms of reproductive performance. All sows were crossbred Swedish Yorkshirex Swedish Landrace. Sows were kept in groups in the breeding section and were also grouped on deep litter in the dry-sow section on all farms. Batchwise farrowing routines were used on all farms, and batch size ranged between 8 and 22 sows. Fertility and culling data were collected in connection with monthly visits to the farms for 16 months. Among the older (≥ 5th parity) sows, litter sizes were significantly (p = 0.02) smaller in the G-farm group compared with the C-farm group. The percentage of sows mated within 10 days post weaning was lower (p<0.001) in the G-farm group than in the C-farm group, with the difference being most evident among the older (≥ 5th parity) sows. The frequency of repeat breeders among primiparous sows was similar in the 2 housing systems, but among the multiparous sows repeat-breeder frequency was higher (p = 0.04) in the G-farm group than in the C-farm group. In both groups, repeat-breeder frequency seemed to be highest from July to September. Repeat breeding/failure to farrow was a common reason for culling in the G-farm group. These results indicate that reproductive performance was impaired in the group-housing system. This impairment could have been due partly to the occurrence of lactational oestrus, which makes it difficult to maintain adequate routines for oestrous detection and mating/insemination.     

Energy Metabolism During Late Gestation and Lactation in Muciparous Sows in Relation to Backfat Thickness and the Interval from Weaning to First Oestrus

Ten crossbred, fourth or fifth parity sows were divided into 2 groups - high (H) and low (L) - according to their backfat thickness 9 days before parturition. Body weight, backfat thickness and litter weight were recorded repeatedly during a 5 week lactation period. The length of the interval from weaning to first oestrus was also noted. All sows were fed a commercial diet (11.9 MJ/kg, 14.5% crude protein). During gestation, daily food intake was 2.2 kg/sow, while during lactation it was 3.0 kg/sow plus 0.4 kg/piglet. Blood samples were drawn on day 9 before parturition and on days 2,7,14 and 21 of lactation. The samples were analysed to determine concentrations of glucose, urea nitrogen, creatinine, triglycerides, free fatty acids and beta-hydroxybutyric acid. In both groups, concentrations of free fatty acids and urea nitrogen were low on day 9 before parturition while those of triglycerides were high, indicating anabolism regardless of backfat thickness. During the first week of lactation, concentrations of free fatty acids increased in the H-group but not in the L-group, and concentrations of urea nitrogen were higher in the H-group. These differences, together with the greater loss of weight observed in the H-group, indicate that catabolism of maternal fat and protein depots was more pronounced in the Η-group than in the L-group during this time. On day 14 of lactation, both groups showed equally low concentrations of free fatty acids, decreasing creatinine concentrations and stable triglyceride and urea nitrogen concentrations. Furthermore, weight loss during the second and third weeks of lactation was low in both groups. These facts, taken together, indicate that the catabolic rate was decreasing in both groups during this period. No differences in return to oestrus interval were noted between the groups. The present study indicates that under a restricted feeding regime the catabolic rate during the first week of lactation is higher in sows with higher backfat thickness in late gestation. As lactation progresses, a more balanced metabolism is achieved regardless of backfat thickness, which may tend to reduce differences in return to oestrous interval.     

Serum Electrolyte and Mineral Variations During Pregnancy and Lactation in Nili-Ravi Buffalo

The aim of present study was to determine the changes of sodium, potassium, chloride, copper, and zinc in serum of Nili-Ravi buffalo during pregnancy and lactation. The study was carried out on 25 Nili-Ravi buffaloes during March 2008 to February 2009 at Buffalo Research Institute, Pattoki, District Kasur. Blood samples were taken from each buffalo during early pregnancy (Phase EP), i.e., between 1 and 3 months gestation, mid pregnancy (Phase MP), i.e., between 4 and 6 months gestation, late pregnancy (Phase LP), i.e., between 7 and 10 months gestation, and during lactation (Phase LT). Serum sodium, potassium, and chloride were determined on a clinical chemistry analyzer whereas copper and zinc were determined on an atomic absorption spectrophotometer. The mean serum sodium, potassium, and chloride concentrations varied non-significantly (P > 0.05) during pregnancy and lactation. With advancing pregnancy, copper increased and was significantly high (P < 0.05) during late pregnancy whereas during lactation copper concentrations dropped significantly (P < 0.05). The zinc concentrations increased non-significantly during early and mid pregnancy. There were significant differences (P < 0.05) in zinc concentrations during lactation compared with late pregnancy. This study demonstrates that concentrations of serum sodium, potassium, and chloride remain unchanged during pregnancy and lactation whereas serum copper concentrations increased and zinc concentrations decreased with advancing pregnancy because of the demand of the fetus at different periods of pregnancy.     

Plasma Thyroxine in the Sow During Pregnancy and Lactation and During Resumption of Ovarian Activity After Weaning

Total thyroxine in plasma was studied during pregnancy, lactation and during the post weaning period. The ovarian activity was monitored by progesterone determinations, and oestrous symptoms were recorded. In the two sows studied during pregnancy there was a distinct decrease in total thyroxine values in the last month of pregnancy, reaching a minimum about the time of farrowing. Total thyroxine values stayed low during lactation, but from about the time of weaning and during the following two weeks the concentrations increased rapidly. There was no difference in the thyroxine pattern in sows resuming ovarian activity within normal time (10 days) after weaning (72 sows) compared with sows with delayed resumption of ovarian activity (19 sows). The thyroxine level after weaning did not differ between sows with “silent 11631” and sows with overt oestrus. Primiparous and pluriparous sows had also similar thyroxine values after weaning. Sows weaned in January—June had a little higher thyroxine concentrations after weaning than sows weaned in July—December. There was a significant negative correlation between number of suckling piglets and thyroxine concentrations before weaning. Free thyroxine index was calculated in some selected samples. The results suggested that the changes observed in total thyroxine reflect changes in the free thyroxine concentrations.     

Stability of the Maternal Gut Microbiota During Late Pregnancy and Early Lactation

Scarce research has been performed to assess whether the human maternal gut microbiota undergoes changes during the perinatal period. Therefore, in the present study, gut microbiota composition of seven healthy mothers(to-be) was assessed at different time points during the perinatal period (i.e. weeks 3–7 prepartum and days 3–6, 9–14, and 25–30 postpartum) using quantitative polymerase chain reaction (qPCR) and pyrosequencing, and was complemented by short-chain fatty acids (SCFA) and calprotectin quantification using high-performance liquid chromatography and enzyme-linked immunosorbent assay, respectively. qPCR revealed the predominance of members of the Firmicutes, Bacteroides, and Bifidobacterium without detectable changes over the perinatal period. Pyrosequencing supported these data in terms of microbiota stability for any population at any taxonomic level, although ratios of members of the Actinobacteria and Bacteroidetes differed between the two methods. However, the number of operational taxonomic units observed by pyrosequencing was subjected to fluctuations and the relative abundance of Streptococcus decreased numerically postpartum (P = 0.11), which may indicate that aberrancies in subdominant populations occur perinatally. Furthermore, total fecal SCFA concentrations, particularly the branched-chain fatty acids isobutyrate and isovalerate, were higher than for non-pregnant subjects throughout the perinatal period. This suggests metabolic changes and increased energy extraction via proteolytic, in addition to saccharolytic fermentation, accompanied by low-grade inflammation based on fecal calprotectin levels. Our data show that the maternal gut microbiota remained stable over the perinatal period despite altered metabolic activity and low-grade inflammation; however, it remains to be confirmed whether changes preceded earlier during pregnancy and succeeded later postpartum.     

Effect of Different Iodine Nutrition on Cerebellum Pcp-2 in Rat Offspring During Lactation

The thyroid functions of breastfed infants, as well as (indirectly) the development of their central nervous system, are dependent on the iodine status of the lactating mother. Purkinje cell protein-2 is a cell-specific marker of the cerebellum Purkinje cell and is a suitable indicator for observing the postnatal development of the cerebellum after birth. We measured the Purkinje cell protein-2 mRNA and protein levels in the rat cerebellum in the critical postnatal (14 days after birth) and maturation periods (28 days after birth) to determine the effect of different nutritional iodine levels on cerebellum growth in the offspring during lactation. We found that severe iodine deficiency resulted in thyroid dysfunction in lactating rats and their offspring on both 14 and 28 days, showing maternal total T₄ 16.7 ± 12.0 vs 36.4 ± 15.0, P < 0.05 (14 days) and 22.6 ± 18.7 vs 53.4 ± 9.4, P < 0.01 (28 days), and neonatal total T₄ 10.6 ± 2.3 vs 16.4 ± 4.7, P < 0.01(14 days) and 12.8 ± 2.9 vs 16.7 ± 3.4, P < 0.05 (28 days), respectively. The Purkinje cell protein-2 mRNA and its protein levels in offspring rats were significantly reduced that showed Purkinje cell protein-2 mRNA 1.12 ± 0.04 vs 2.25 ± 0.53, P < 0.05 (14 days) and 1.74 ± 0.94 vs 8.69 ± 2.71, P < 0.01 (28 days). However, mild iodine deficiency and excessive iodine maintained almost normal thyroid function in maternal and neonatal rats and normal Purkinje cell protein-2 mRNA and protein levels in offspring’s cerebellum. We conclude that severe iodine deficiency could significantly reduce Purkinje cell protein-2 mRNA and its protein levels, indicating that the cerebellum development was retarded, but mild iodine deficiency and excessive iodine could maintain them at an approximately normal level by the mother’s and offspring’s compensations, especially by the mother’s mammary glands.     

尖叶拟船叶藓种群能量生殖配置的研究

首次报道了苔藓类植物的能量生殖配置情况.在尖叶拟船藓(Dolichomitriopsis diversiformis)种群整个生长周期中,各器官热值由大到小顺序为:雌器苞(9305.1 J/g)＞成熟孢子体(9196.1 J/g)＞配子体(4075.6 ～ 6558.6 J/g).能量配置比例的顺序为:配子体>孢子体>雌器苞.配子体生长所分配的能量占绝对优势,成熟孢子体的能量配置仅为3.2 %.实验结果表明:尖叶拟船叶藓生殖器官(雌器苞和孢子体)的能量配置较低,但具有较高的热值,生殖期需要消耗较多的能量.     

Maternal Undernutrition During Lactation: Effect on Amino Acids in Brain Regions of Offspring

Sprague-Dawley dams were fed either a protein-calorie deficient or control diet from day 5 to day 21 after parturition. The concentrations of seven amino acids (aspartate, glutamate, gamma-aminobutyric acid, glycine, glutamine, serine, and taurine) were determined in brain regions from 17-day-old undernourished offspring and from 35-day-old rehabilitated rats. The brain regions examined were the cortex, cerebellum, corpus striatum, hippocampus, hypothalamus, brainstem, and midbrain. At 17 days of age, taurine was the amino acid with the highest concentration, whereas at 35 days glutamate had the highest concentration. This change was due to the fact that the concentration of taurine decreased significantly in all brain regions between 17 and 35 days, whereas the concentration of glutamate remained high or increased somewhat in all brain regions except the hypothalamus and brainstem. When the age-matched offspring of control and undernourished rats were compared, several interesting and significant differences were found. The concentrations of glutamate and aspartate were significantly lower (decreased 16-34%) in the cerebellum, brainstem, cortex, and midbrain in 17-day-old undernourished rats. The aspartate level was also significantly decreased in the corpus striatum and hypothalamus in 17-day-old offspring. However, the deficiencies of aspartate and glutamate were transient and reversible. In contrast, the concentration of taurine was increased in the hypothalamus (31%) and hippocampus (12-33%) at both 17 and 35 days of age and in the midbrain (17%) at 17 days. Other transient abnormalities in amino acid levels were found in undernourished offspring. The results of these experiments suggest that undernutrition during lactation causes delayed CNS development, which is manifested in altered concentrations of the neurotransmitters aspartate, glutamate, and taurine.     

哺乳期幼麝的摄食时间分配研究

采用所有事件取样法对哺乳期林麝Moschus berezorskii幼体的摄食时间分配进行研究.结果 表明,幼麝吮乳时间随周龄的增加而减少,取食固体饲料(青饲料和混合饲料)的摄食时间随周龄的增加而增加.1月龄中,吮乳时间占总摄食时间的90.8%,青饲料占9.2%.2月龄和3月龄中,幼麝取食固体饲料时间分别占总摄食时间的84.7%和94.9%,吮乳时间分别占15.3%和5.1%.哺乳期雌性幼麝取食母乳、山芋藤和桑叶的时间明显高于雄性幼麝(P＜0.05),而取食精饲料、苦荬菜时间与雄性幼麝无明显差异(P＞0.05);单胎幼麝吮乳、取食山芋藤时间明显高于双胎幼麝(P＜0.05);而取食精饲料、苦荬菜时间明显低于双胎幼麝(P＜0.05),两者取食桑叶时间差异性不显著(P＞0.05).幼麝的摄食时间分配表明,母乳是1月龄幼麝的主要食物成分;2月龄以后,幼麝大量取食固体饲料,母乳在食物组成中退居次要作用.幼麝间吮乳时间的差异反映了不同个体间营养状况的差异.     

A Chlorophyll Fluorescence Analysis of the Allocation of Radiant Energy Absorbed in Photosystem 2 Antennae of Cotton Leaves During Exposure to Chilling

When dark-acclimated cotton (Gossypium hirsutum L. cv. Coker 312) leaves, pre-treated with lincomycin to inhibit chloroplast protein repair processes, were exposed to 10 °C and a PPFD of 500 mol m^-2 s^-1, the proportion of excitation energy entering photochemistry (P) increased, but only to 5 % of the total energy absorbed at steady state levels of P, which were reached at 40 min of irradiation. Thermal dissipation (D) of absorbed energy increased throughout the 360 min irradiation period and accounted for the greatest portion of absorbed energy at 10 °C. When D was partitioned into constitutive (D_CON), regulated (D_REG), and photoinhibitory (D_PI) components, it was primarily composed of D_REG, the readily reversible portion of D. However, the induction of D was slow at 10 °C. Sixty minutes were required for D to reach 70 % of the energy absorbed. Considerable absorption of energy in excess of that utilized in photochemistry or dissipated thermally (designated as E) occurred, especially during induction of P and D. Over the irradiation period, the time-dependent averaged E exhibited an inverse, linear relationship with the ratio of variable (F_v) to maximum (F_m) fluorescence (PS2 efficiency) and a linear relationship with D_PI. We propose that time-dependent averaged E may be useful for estimating the potential for damage to PS2 under stressful environmental conditions.     

Double Effects of Age and Environment on Resource Allocation Trade-offs of Salix psammophila in Different Microtopographic Habitats of a Sand Dune

Journal of Plant Growth Regulation - Adjustments to the allocation of aboveground biomass allocation are an important component of the adaptive strategies of plant growth. Plants can modify their...     

Programmed Trade-offs in Protein Folding Networks

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温度和增加胎仔数对大绒鼠哺乳期能量代谢的影响

为了阐明温度和增加胎仔数对大绒鼠Eothenomys miletus哺乳期能量代谢的影响,本研究测定了在不同温度条件下增加胎仔数(比正常胎仔数多),大绒鼠的摄食量、胎仔数、胎仔质量、静止代谢率、非颤抖性产热和乳腺质量。结果表明:不同胎仔数对大绒鼠的摄食量、胎仔质量和产热能力没有影响。低温增加了母体的摄食量和产热能力,断奶时低温组的胎仔质量显著低于常温组。低温组和常温组大绒鼠的乳腺质量差异无统计学意义。研究结果说明低温可以增加大绒鼠摄食量,但是对乳腺质量没有影响,表明大绒鼠哺乳期的持续能量摄入上限可能受到乳腺分泌乳汁的限制,支持外周限制假说。