Activity rhythms of enzymes in human red blood cell suspensions

Abstract

We have established the presence of a rhythm in the activity of 4 enzymes in in‐vitro cell suspensions of human red blood cells. Glucose 6‐phosphate dehydrogenase and glutamate oxaloacetate transaminase demonstrated semicircadian patterns of activity, while acid phosphatese and acetylcholine esterase exhibited circadian activity rhythms. The ratios between the highest to lowest activities varied from 2:1 to 10:1 among the various enzymes. The affinity of glucose 6 phosphate dehydrogenase to its substrate and coenzyme remained constant throughout the cycle. No evidence was obtained for the presence of a soluble inhibitor at the lower levels of the activity. Sonication of hemolysates with low glucose 6 phosphate dehydrogense activity yielded additional activity comparable to that of the peak activity. Sonication of hemolysates from the time of the peak activity did not change the original activity. The observations point to a role of the cell membrane in the biological clock.     

Phase control of circadian activity in the antelope ground squirrel

Abstract

Wheel‐running activity of forty antelope ground squirrels, Ammospermophilus leucurus, was monitored for several months in both an outdoor cage and in the laboratory. The squirrels demonstrated a highly diurnal pattern which persisted in “constant conditions.” After removal from the field the initial free‐running period was close to 24 hrs, but typically lengthened in a nearly linear fashion at least for the first few months. There was no evidence of any difference in this trend for squirrels, in D/D, L/L 100 lx, 250 lx or 1200 lx. Eventually, about 90 percent of the squirrels had periods longer than 24 hrs.

The synchronizing capacity of the natural photoperiod was used to “catch the free‐running rhythm” and thereby demonstrate a response curve. Synchronization occurred by a shortening of the period when the time of sunrise was between 125° and 0° (subjective night) and by a lengthening of the period when the time of sunrise was between 0° and 125° (subjective day).

To more thoroughly examine the underlying mechanisms of phase control, phase‐response curves based on sixty one light‐pulse experiments were constructed. Comparisons of curves based on 6‐hr and 15‐min pulses, showed that the integral action of light is important (i.e., the entire pulse is involved in phase shifting). It was found that light pulses not only affected the phase of the rhythm but also the phase. Large phase shifts were usually associated with decreases in free‐running period. Several hypotheses on the controlling mechanisms were advanced.     

A change in the pattern in circadian running‐wheel activity after lesions of the intergeniculate leaflet and ventral lateral geniculate nucleus in the Syrian hamster

Abstract

The suprachiasmatic nuclei (SCN) contain the endogenous mammalian circadian pacemaker, which generates the circadian rhythm in locomotor activity. In Syrian hamsters with free‐running rhythms, the onset of running‐wheel activity is very precise and predictable while the end (offset) is more variable. From the thalamic intergeniculate leaflet (IGL) and the ventral lateral geniculate nucleus (vLGN) a projection to the SCN originates. Animals with a lesion aimed at the IGL/vLGN and sham‐and unoperated controls were kept in continuous darkness. With linear regression, lines were fitted through 10 successive onsets and offsets of activity and the mean deviation of the onsets and offsets from the fitted lines was determined. Animals with a complete or partial lesion of the IGL/vLGN had a smaller mean deviation of the circadian activity offset from the fitted regression line (0.313 h) compared with the grouped control animals (0.678 h). To test the difference statistically, we compared the sum of the square residuals of the circadian offsets between the groups. This difference was highly significant (F(69,64)=4.16, p<0.0001), which indicates that animals with a lesion of the IGL/ vLGN have a less variable circadian offset of running‐wheel activity. No differences were observed in the variability in the circadian onset of locomotor activity between experimental and control animals. It is concluded that the IGL/vLGN influence the variability of the offset of the circadian running‐wheel activity.     

不同产地天麻氨基酸的含量测定

氨基酸用途广泛,人们对氨基酸质量和品种的要求也越来越高.我国氨基酸从无到有,到现在的大市场份额,经历了五十多年的发展历程,其中包括谷氨酸、赖氨酸、苏氨酸和蛋氨酸在内的大品种氨基酸已经发展成为全球的主要供应品种,部分小品种氨基酸已形成自己的优势.绿色制造和现代生物技术的应用将成为氨基酸行业发展的主流.本文重点论述了我国氨基酸品种的现状、水平以及未来发展方向.     

Der Mengen- und Spurenelementgehalt des Rinderhaares als Indikator der Calcium-, Magnesium-, Phosphor-, Kalium-, Natrium-, Eisen-, Zink-, Mangan-, Kupfer-, Molybdän- und Kobaltversorgung

Beyond the energy requirement of maintenance, the assimilated energy, occurring in bioproducts, is linearly proportional to the intake of metabolizable energy in non‐underfed conditions. In contrast, resting metabolic rate is differing between individuals within a population of an animal species. As adaptability to changed environmental conditions may play a role, young bulls were exposed to thermoneutral (18°C) and low (4°C) ambient temperatures and were fed at two feeding levels (1.0 and 1.6 times energy requirement in maintenance) to produce metabolic rate differences, using the same animals, metabolic rate was altered by reducing the sympathetic outflow in each case. Expression of sulfonylurea receptors in circulating mononuclear leukocytes and cells from skeletal muscle (m. semitendinosus) was studied by flow cytom‐etry. Changes of metabolic rate at rest corresponded to the portion of cells with sulfonylurea receptors expression. The data from reducing the sympathetic outflow and those from sulfonylurea receptors expression are useful to explain metabolic rate differences among individuals of an animal population.     

Effects of fibre concentration of diets consisting of hay and slowly degradable concentrate on ruminal fermentation and digesta particle size in mid-lactation dairy cows

The objective of this study was to investigate the intestinal microbiota of growing kittens fed moderate- or high-protein diets using DNA-based qualitative and quantitative techniques. Kittens were weaned to a high-protein (HP; n = 7) or moderate-protein (MP; n = 10) diet at 8 weeks of age. Fresh faecal samples were collected at 8, 12, and 16 weeks of age. DNA was extracted and quantitative PCR used to quantify Bifidobacterium, Lactobacillus, Clostridium perfringens, and Escherichia coli concentrations. Denaturing gradient gel electrophoresis was performed to create a dendrogram and unrooted trees using Bionumerics 5.0 to identify similarity due to litter, age, or diet. Kittens fed HP had lower (p = 0.02) Bifidobacteria and Lactobacillus counts than MP-fed kittens. E. coli was lower (p = 0.02) in HP-fed kittens and tended to be affected by age (p = 0.09). Kittens were clustered by litter at 8 weeks of age, and then clustered by diet at 12 and 16 weeks of age. Our data suggest that faecal microbiota of growing kittens change after weaning and that dietary protein concentration affects E. coli, Bifidobacterium, and Lactobacillus populations. The relevance of these data in terms of intestinal health and disease remain to be determined and justifies further study.     

Diet choice by goats as effect of milk production level during late lactation

The diet self-regulation ability of goats during late lactation has been studied with regard to their production level. Two groups of seven Girgentana goats producing 1100 ± 157 g/day (H group) and 613 ± 138 g/day (L group) were housed in individual pens and were given alfalfa pelleted hay (1.5 kg), whole grains of maize (0.5 kg), barley (0.5 kg), faba bean (0.5 kg) and pelleted sunflower cake (0.5 kg) on a daily basis. During a 7-day pre-experimental period, goats received a mixed ration based on the same feeds used during the experimental period (1.5 kg of hay and 0.4 kg of each concentrate). Individual choice of feeds was continuously recorded for 7 days using a 24-h IR video surveillance system equipped with four video cameras. The nutrient intake in both groups was much higher than needed. Goats in the H group ate more (2016.3 v. 1744.3 g dry matter (DM)/day) and selected less hay (26.9% v. 34.6% DM), more high-protein feeds (faba bean and sunflower cake: 14.0% and 15.9% v. 8.8% and 7.9% DM, respectively) and less maize (21.5% v. 25.0% DM), reaching a higher CP concentration in the diet (17.3% v. 15.0% DM) compared with the goats in the L group. During the 24-h trial period, hay was more constantly selected (on average never reaching <20% of the total hourly basis feeding time, apart from the first hour after feed administration) compared with concentrate feeds. This feeding behaviour has probably exercised a ‘curative’ effect that enabled the goats to continue to take in very high levels of starch and protein, without manifesting any symptom of metabolic disease. Shifting goats from the pre-experimental diet, based on a mixture of the same feeds used during the experimental period, to the free-choice feeding caused more than 20% increase in milk production in both groups. From the results of the intake, we are unable to conclude that the goats can select their diet to meet their requirements, as goats consumed much more than needed. However, when free to choose their diet, the animals improved milk performance, despite the late-lactation stage.     

Changes in the genetic level and the effects of age at first calving and milk production on survival during the first lactation over the last 25 years

Survival during the first year after first calving was investigated over the last 25 years, 1989–2013, as well as how the association of survival with season of calving, age at first calving (AFC) and within-herd production level has changed over that period. The data set contained 1 108 745 Dutch black-and-white cows in 2185 herds. Linear models were used to estimate (1) effect of year and season and their interaction and (2) effect of AFC, within-herd production level, and 5-year intervals and their two-way interactions, and the genetic trend. All models contained AFC and percentage of Holstein Friesian as a fixed effect, and herd-year-season, sire and maternal grandsire as random effects. Survival and functional survival were analysed. Functional survival was defined as survival adjusted for within-herd production level. Survival rate increased by 8% up to 92% in the last 25 years. When accounting for pedigree, survival showed no improvement up to 1999, but improved since then. Genetically, survival increased 3% to 4% but functional survival did not increase over the 25 years. We found an interesting difference between the genetic trends for survival and functional survival for bulls born between 1985 and 1999, where the trend for survival was still increasing, but was negative for functional survival. Since 1999, genetic trend picked up again for both survival and functional survival. AFC, season of calving and within-herd production level affected survival. Survival rate decreased 0.6%/month for survival and 1.5% for functional survival between AFC of 24 and 32 months. Calving in summer resulted in 2.0% higher survival than calving in winter. Within herd, low-producing cows had a lower survival rate than high-producing cows. However, these effects became less important during the recent years. Based on survival optimum AFC is around 24 months, but based on functional survival it is better to have an AFC<24 months. Overall, survival rate of heifers has improved considerably in the past 25 years, initially due to the focus on a high milk production. More recently, the importance of a high milk production has been reduced towards attention for functional survival.     

应用分子标记技术改良京作1号的稻瘟病抗性

稻瘟病是危害水稻产量的重要生物胁迫之一。实践证明,解决这一问题的最有效方法是培育具广谱、持久稻瘟病抗性的品种并推广种植。本研究以优质、高产、感稻瘟病的京作1号为轮回亲本,与稻瘟病抗性基因Pi9、Pigm和pi21的供体材料进行杂交、回交和复交,结合分子标记辅助选择和农艺性状筛选,培育不同的单基因导入系和聚合系。苗期人工接种多个稻瘟病菌的结果显示,Pi9抗性改良系的抗性频率达到100%,Pigm抗性改良系平均为90%,均极显著高于轮回亲本京作1号的抗性频率,且农艺性状与京作1号基本一致。pi21抗性改良系的抗性水平与京作1号没有明显差异,单株产量极显著低于京作1号。与轮回亲本相比,Pi9和pi21聚合系的抗性频率极显著提高,达到93.33%,但单株产量明显降低。研究结果证实了Pi9和Pigm基因在大幅度提高抗瘟性的同时对主要农艺性状影响小,都具有较大的育种利用价值。基因pi21抗谱较窄,抗性不强,且可能存在对产量的负效应,不宜单独用来改良水稻品种的稻瘟病抗性,需要与抗性强的主基因聚合,通过多次回交和自交打破该基因与产量的不利连锁累赘。