Passive irrigation and functional morphology of crustacean burrows in a tropical mangrove swamp

Flushing measurements and a resin cast of a burrow inhabited by Sesarma messa and Alpheus cf macklay were taken from a Rhizophoraspp. forest. The burrow had 9 openings and occupied a swamp surface area of 0.64 m². Passive irrigation of the burrow was investigated by recording change in conductivity of burrow water in a chamber 45 cm below the swamp surface during tidal inundation of the swamp. The chamber was completely flushed within approximately one hour, i.e. by a single tidal event. Burrow morphology was determined by means of resin casting. The investigated burrow was of discrete structure, with an overall depth of 1.2 m and a total volume of 68 l, i.e. ca. 9% of the volume of swamp soil. The below ground surface area of chambers and tunnels was 3.8 m². The mean and maximum chamber/tunnel diameter was 7 cm and 11 cm respectively. The soil in the close vicinity of the burrow was extensively penetrated by roots, and any two parts of the burrow were located no further than 20 cm away from each other. By reducing diffusion distances within the soil and by being well flushed, the burrows provide an efficient mechanism for removal of excess salt accumulated in the soil around mangrove roots due to exclusion.     

The Thatcher illusion in humans and monkeys

Primates possess the remarkable ability to differentiate faces of group members and to extract relevant information about the individual directly from the face. Recognition of conspecific faces is achieved by means of holistic processing, i.e. the processing of the face as an unparsed, perceptual whole, rather than as the collection of independent features (part-based processing). The most striking example of holistic processing is the Thatcher illusion. Local changes in facial features are hardly noticeable when the whole face is inverted (rotated 180°), but strikingly grotesque when the face is upright. This effect can be explained by a lack of processing capabilities for locally rotated facial features when the face is turned upside down. Recently, a Thatcher illusion was described in the macaque monkey analogous to that known from human investigations. Using a habituation paradigm combined with eye tracking, we address the critical follow-up questions raised in the aforementioned study to show the Thatcher illusion as a function of the observer''s species (humans and macaques), the stimulus'' species (humans and macaques) and the level of perceptual expertise (novice, expert).     

Decoding at the ribosomal A site: antibiotics, misreading and energy of aminoacyl-tRNA binding

The binding of Phe-tRNAPhe at the programmed ribosomal A site has been investigated using antibiotics that influence this binding in different ways. The adhesion of Phe-tRNAPhe, the consumption of GTP and the extent of the peptidyl transfer reaction were monitored. All of the five known misreading-inducing antibiotics that were tested stabilised the binding of Phe-tRNAPhe after its affixture to the A site by EF-Tu with GTP hydrolysis. The stabilisation was sufficient to overcome a single mismatch in the codon-anticodon interaction. Combinations of stabilising and destabilising influences were found to be additive, thus supporting the concepts: (1) that there is a 'correct' binding energy for aminoacyl tRNA in the A site, whose reduction hampers polypeptide synthesis and whose increase makes it inaccurate by by-passing proofreading; and (2) that the different antibiotics affect the bound aminoacyl tRNA at different points.     

内蒙古部分地区骆驼和羊寄生蜱虫病毒组学分析

为了解内蒙古地区蜱虫病毒组学的本底数据,采用病毒宏基因组学方法对在内蒙古阿拉善盟左旗、右旗和四子王旗地区3个采样点采集骆驼和羊体表寄生的1789只蜱虫样品进行病毒宏基因组学分析,并对特定病毒进行巢式PCR扩增和测序,通过Clustal W和MEGA7.0等生物信息学软件对获得的病毒基因序列进行遗传进化分析.数据显示,蜱虫样品携带包括植物、脊椎动物和非脊椎动物等来源的17个病毒科和一些未分类的病毒;其中,2株弹状病毒具有丰富的遗传多样性,与新疆地区和长江地区的弹状病毒的同源性达到98.5％和96.26％,提示蜱虫弹状病毒可能是通过羊和骆驼等动物贸易导致了新疆和内蒙古地区,以及内地的跨区域传播;细小病毒仅在羊来源的蜱虫中检测到,与中国河北地区的山羊血清中的细小病毒形成同一进化分支,我们推测蜱虫细小病毒在国内不同地区间可跨区域传播,在进化分析过程中,发现这种病毒与多种的细小病毒的同源性都不低于50％,提示细小病毒可能具有遗传稳定性;Tamdy病毒与来自阿塞拜疆、乌兹别克斯坦和美国的Tamdy病毒均具有极高的同源性,结果显示该病毒在内蒙古地区已经出现,并存在潜在流行的可能,有必要对Tamdy病毒进行进一步的监测;在本研究中,我们鉴定的白蛉病毒与来自新疆的亚洲璃眼蜱所携带的博乐蜱虱病毒形成同一个进化分支,与新型布尼亚病毒和Heartland virus病毒的同源性达到50％以上,该结果提示,我们发现的蜱虫白蛉病毒可能具有潜在的致病性,需要对其流行情况和致病性进行监测和研究.本研究为完善内蒙古部分地区蜱虫病毒的多样性和本底情况提供了重要的基础数据.     

The imprecision of the ratio of two percentages observed in differential white blood cell counts: a warning

Ratios of two percentages observed in differential counts of leukocytes or lymphocytes are very imprecise if they are based on relatively small numbers of cells. This is shown by the length of the 95% confidence intervals for such ratios. A formula is given for computing the limits of such intervals. They should accompany each observed value for a ratio.     

Parallel dose-response curves in combination experiments

A possible experimental design for combination experiments is to compare the doseresponse curve of a single agent with the corresponding curve of the same agent using either a fixed amount of a second one or a fixed dose ratio. No interaction is then often defined by a parallel shift of these curves. We have performed a systematic study for various types of doseresponse relations both for the dose-additivity (Loewe additivity) and for the independence (Bliss independence) criteria for defining zero interaction. Parallelism between doseresponse curves of a single agent and those of the same agent in the presence of a fixed amount of another one is found for the Loewe-additivity criterion for linear doseresponse relations. For nonlinear relations, one has to differentiate between effect parallelism (parallel shift on the effect scale) and dose parallelism (parallel shift on the dose scale). In the case of Loewe additivity, zero-interaction dose parallelism is found for power, Weibull, median-effect and logistic doseresponse relations, given that special parameter relationships are fulfilled. The mechanistic model of competitive interaction exhibits dose parallelism but not effect parallelism for Loewe additivity. Bliss independence and Loewe additivity lead to identical results for exponential doseresponse curves. This is the only case for which dose parallelism was found for Bliss independence. Parallelism between single-agent doseresponse relations and Loewe additivity mixture relations is found for examples with a fixed doseratio design. However, this is again not a general property of the design adopted but holds only if special conditions are fulfilled. The comparison of combination doseresponse curves with single-agent relations has to be performed taking into account both potency and shape parameters. The results of this analysis lead to the conclusion that parallelism between zero interaction combination and single-agent doseresponse relations is found only for special cases and cannot be used as a general criterion for defining zero-interaction in combined-action assessment even if the correct potency shift is taken into account.     

Why do antioxidants fail to provide clinical benefit?

The results of recent randomized trials to test the influence of antioxidants on coronary-event rates and prognosis in patients with coronary-artery disease were disappointing. In none of these studies did the use of vitamin E improve prognosis. In contrast, treatment of coronary-artery disease with angiotensin-converting-enzyme (ACE) inhibitors reduced coronary-event rates and improved prognosis. ACE inhibition prevents the formation of angiotensin II, which has been shown to be a potent stimulus of superoxide-producing enzymes in atherosclerosis. The findings suggest that inhibition of superoxide production at enzymatic levels, rather than symptomatic superoxide scavenging, may be the better choice of treatment.     

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.