Detection of genetic variants affecting cattle behaviour and their impact on milk production: a genome‐wide association study

Behaviour traits of cattle have been reported to affect important production traits, such as meat quality and milk performance as well as reproduction and health. Genetic predisposition is, together with environmental stimuli, undoubtedly involved in the development of behaviour phenotypes. Underlying molecular mechanisms affecting behaviour in general and behaviour and productions traits in particular still have to be studied in detail. Therefore, we performed a genome‐wide association study in an F₂ Charolais × German Holstein cross‐breed population to identify genetic variants that affect behaviour‐related traits assessed in an open‐field and novel‐object test and analysed their putative impact on milk performance. Of 37 201 tested single nucleotide polymorphism (SNPs), four showed a genome‐wide and 37 a chromosome‐wide significant association with behaviour traits assessed in both tests. Nine of the SNPs that were associated with behaviour traits likewise showed a nominal significant association with milk performance traits. On chromosomes 14 and 29, six SNPs were identified to be associated with exploratory behaviour and inactivity during the novel‐object test as well as with milk yield traits. Least squares means for behaviour and milk performance traits for these SNPs revealed that genotypes associated with higher inactivity and less exploratory behaviour promote higher milk yields. Whether these results are due to molecular mechanisms simultaneously affecting behaviour and milk performance or due to a behaviour predisposition, which causes indirect effects on milk performance by influencing individual reactivity, needs further investigation.     

Food sharing: a model of manipulation by harassment

Most analyses of food-sharing behavior invoke complex explanationssuch as indirect and delayed benefits for sharing via kin selectionand reciprocal altruism. However, food sharing can be a moregeneral phenomenon accounted for by more parsimonious, mutualisticexplanations. We propose a game theoretical model of a generalsharing situation in which food owners share because it is in their own self-interest—they avoid high costs associatedwith beggar harassment. When beggars harass, owners may benefitfrom sharing part of the food if their consumption rate islow relative to the rate of cost accrual. Our model predictsthat harassment can be a profitable strategy for beggars if they reap some direct benefits from harassing other than sharedfood (such as picking up scraps). Therefore, beggars may manipulatethe owner's fitness payoffs in such a way as to make sharingmutualistic.     

Minireview: Metabolic control of the reproductive physiology: Insights from genetic mouse models

This article is part of a Special Issue Energy Balance.     

Use of novel objects to enhance environments of captive chimpanzees

A small group of chimpanzees was allowed to manipulate different quantities of novel objects in order to enhance their captive conditions. This procedure led to a general increase in the manipulation frequency by the apes. It decreased their inactivity and their self-grooming, and almost eliminated the abnormal behaviors displayed by one individual. The distribution of novel objects did not affect the total frequency of social interactions and did not increase the aggressivity of the animals, even though dominant individuals secured most of the objects when only a small number of them were available. Following their familiarization with the novel objects, the chimpanzees' manipulation frequency decreased whereas self-grooming and abnormal behaviors were increased. Suggestions are made on how to maximize the use of a limited bank of toys to occupy captive chimpanzees.     

Size-dependent drift responses of mayflies to experimental hydrologic variation: active predator avoidance or passive hydrodynamic displacement?

Summary Larger nymphs within aquatic insect taxa have been frequently observed to be transported down-stream in the stream drift only at night. Others have hypothesized this pattern results primarily from large nymphs' behavioural avoidance of entering drift during daylight, when size-selective, visually-feeding fish predators are most active. This hypothesis assumes that animals can actively control their entry into the drift, which may not be the case under all flow conditions. We experimentally induced streamflow increases and decreases in adjacent riffles in a hydrologically-stable stream during the daytime to examine whether changes in diel patterns of drift abundance and size-distribution of mayflies were consistent with the hypothesis of active avoidance of diurnal drift. We assessed the likelihood of active vs. passive mechanisms of diurnal drift entry and transport for four taxa that differ with respect to body size, morpho-behavioural attributes, microhabitat use, and general propensity to drift. In each of three seasons, diurnal and nocturnal drift samples were collected in three riffles over two diel cycles. Background drift patterns were established on the first day (no flow manipulation). Six h before sunset on the second day, flow was experimentally increased in one riffle, decreased in the second, and not altered in the third (control). Between-day differences in diurnal and nocturnal drift rate and size composition were then compared among the treatment and reference riffles. Responses of two taxa were consistent with active control over drift entry, transport, or both. For Baetis spp., drift-prone mayflies typically preyed upon by fish, diurnal drift rates immediately increased following both flow reduction and flow elevation in all seasons, but only small individuals comprised the drift. Drift by large individuals was delayed until nighttime. Epeorus longimanus also exhibited significant increases in drift rates following flow reduction and elevation, but responses of this large-bodied species were restricted to nighttime. Drift responses for these two taxa were largely independent of direction of hydrologic change, thus indicating a strong behavioural control over drift. By contrast, numbers and sizes of drifting Paraleptophlebia heteronea and Ephemerella infrequens depended strongly on direction of flow change. Drift rates for both species generally declined after flow reduction and increased after flow elevation. Moreover, after flow elevation, larger individuals often drifted diurnally, a finding consistent with expectations under a passive hydrodynamic model. These experiments indicate that size-dependent mayfly drift reflects not only presumed risk from visual fish predators, but also functional attributes of species such as morphology, behaviour, and microhabitat affiliation, which influence aspects of drift entry and transport under variable hydrologic conditions.     

Experimental manipulations of the phytoplankton periodicity in large limnetic enclosures in Blelham Tarn,English Lake District

This paper reviews the results of experimental manipulations, carried out during the period 1977–1983, on the phytoplankton maintained in the limnetic enclosures at Blelham Tarn, English Lake District. Three categories of manipulations are considered.The effects of variation in the scale and frequency of phosphorus loading (range: 0.3 to 2.5 g P m^–2 a^–1) upon the mean phytoplankton biomass, its seasonal distribution and specific dominance are shown to conform to well-established patterns and relationships observed in natural lakes. Much of the seasonal variability in species dominance occurred independently of nutrient ratios, though carbon availability has been critical at times. Attempts to manipulate the rates of removal of phytoplankton by grazing have confirmed that they act selectively against certain smaller species only, that they alter the rate of successional change, rather than its direction, and that they have little lasting influence upon the total phytoplankton standing crop. Attempts to manipulate rates of sinking loss through artificial enlargement of the epilimnetic circulation also regulated the light-conditions experienced by suspended phytoplankton.Growth-rate relationships to an index of light exposure and to temperature fluctuation are also derived for several species and are related to morphological and physiological characters of the organisms concerned. These interpretations are briefly reviewed in relation to periodic cycles in natural lakes.     

培养抗性植物的细胞/组织培养途径

抗性育种在作物品种改良中已日益显得重要。近10多年来,随着细胞/组织培养、遗传操作等生物技术的迅速发展,以及由于植物具有全能性,在人工培养条件下,从单细胞原生质体可以再生成一个完整的个体成功以来,人们试图利用细胞/组织培养等生物技术将野生种的抗性基因引入到作物中来,或是人工诱发抗性变异,从而筛选出抗性愈     

Survival of Pseudomonas fluorescens and Bacillus subtilis introduced into two soils of different texture in field microplots

Abstract Antibiotic-resistant strains of Pseudomonas fluorescens and Bacillus subtilis , produced by transposon Tn5 mutagenesis and transformation with plasmid pFT30, respectively, were characterized. Both strains grew at a rate comparable to that of the wild-type strains, and the antibiotic resistance remained stable for over 50 generations without selective pressure. During the growing season, the survival of these strains was studied in two soils of different texture cropped with wheat. The B. subtilis populations declined rapidly in both soils and then stabilized at the levels of added spores. P. fluorescens showed a slow, steady decline in both soils; survival was better in the finer-textured soil, a silt loam, than in the coarser loamy sand. For both bacteria, some translocation to deeper soil layers was observed. No significant rhizosphere effects were detected in either of the two soils.     

The effects of prolonged emersion and submersion by tidal manipulation on marine macrobenthos

Effects of tidal manipulation, resulting in prolonged periods of emersion and submersion or in protracted tidal cycles, on estuarine benthic animals are reviewed.Prolonged submersion periods did not show effects on mortality of most benthic animals tested, with the exception of the crumb-of-bread sponge Halichondrea panicea, which, at low water-flow rates, was covered with a layer of bacteria and subsequently died.Protracted low-water periods of 18 hours during several weeks hardly caused any mortality. However, protracted low-water periods of 30 hours during some weeks or emersion during several days caused a strong increase in mortality, depending on: the duration of emersion, temperature, condition of the animals, species and age. At temperatures below –1 °C and above 24 °C mortality was generally high. Animals with a low glycogen content were more sensitive to emersion than those with a high content. Species with a shell and those that are relatively big were less sensitive than those without a shell or of small size.The reproductive cycle of benthic animals could be delayed or accelerated by both emersion and submersion.     

Are tissue cultures of Peganum harmala a useful model system for studying how to manipulate the formation of secondary metabolites?

This article reviews our present knowledge on the formation of tryptophan derived secondary metabolites in tissue cultures of Peganum harmala. With the presence of -carboline alkaloids and serotonin, P. harmala contains two rather simple, interrelated biosynthetic pathways. The long term disadvantage of low and unstable productivity of P. harmala suspension culture has recently been overcome by establishing highly productive hairy root cultures. The first -carboline alkaloid biosynthetic enzymes, specific for the O-methylation of harmalol and harmol as well as for the oxidation of harmaline to harmine, have been detected in these cultures, and they should thus provide a suitable source for studying the yet unknown initial two enzymatic steps of -carboline alkaloid biosynthesis. Seedlings of P. harmala have also been successfully transformed with constructed strains of Agrobacterium, as demonstrated by the overexpression of a tryptophan decarboxylase gene from Catharanthus roseus in cultures of P. harmala. In such transgenic cultures a large overproduction of serotonin was observed. The relative simplicity of these pathways and the rather easy handling of the cultures could make P. harmala a useful and attractive model system for studying the interaction, regulation and manipulation of secondary pathways in cultured cells.Abbreviations TDC tryptophan decarboxylase - tdc gene of tryptophan decarboxylase