Interethnic variability in birth weight and genetic background: A study of placental alkaline phosphatase

The relationship between human placental alkaline phosphatase (PLAP) genotype and birth weight is investigated in a sample of white, black and Puerto-Rican new-born infants from New Haven, Connecticut (total 710 subjects). Black and Puerto-Rican infants show a higher incidence of growth retardation and a higher frequency of ALPp^*1/^*1 genotype as compared to whites. The proportion of newborns with a low birth weight (below the 10th percentile) is lower in infants with ALPp^*1/^*1 genotype than in those with other PLAP genotypes, especially among non-whites. It is argued that the higher frequency of ALPp^*1 allele among non-whites might be, at least in part, a consequence of their adaptation in the past to environmental conditions adverse to optimal intrauterine development. © 1996 Wiley-Liss, Inc.     

Geographical distribution and extinction risk: lessons from Triassic–Jurassic marine benthic organisms

Aim To evaluate the influence of geographical distribution on the extinction risk of benthic marine invertebrates using data from the fossil record, both during times of background extinction and across a mass‐extinction episode. Total geographical range is contrasted with proxies of global abundance to assess the relationships between the two essential components of geographical distribution and extinction risk. Location A global occurrence data base of fossil benthic macro‐organisms from the Triassic and Jurassic periods was used for this study. Methods Geographical distributions and biodiversity dynamics were assessed for each genus (all taxa) or species (bivalves) based on a sample‐standardized data set and palaeogeographical reconstructions. Geographical ranges were measured by the maximum great circle distance of a taxon within a stratigraphic interval. Global abundance was assessed by the number of localities at which a taxon was recorded. Widespread and rare taxa were separated using median and percentile values of the frequency distributions of occurrences. Results The frequency distribution of geographical ranges is very similar to that for modern taxa. Although no significant correlation could be established between local abundance and geographical range, proxies of global abundance are strongly correlated with geographical range. Taxon longevities are correlated with both mean geographical range and mean global abundance, but range size appears to be more critical than abundance in determining extinction risk. These results are valid when geographical distribution is treated as a trait of taxa and when assessed for individual geological stages. Main conclusions Geographical distribution is a key predictor of extinction risk of Triassic and Jurassic benthic marine invertebrates. An important exception is in the end‐Triassic mass extinction, which equally affected geographically restricted and widespread genera, as well as common and rare genera. This suggests that global diversity crises may curtail the role of geographical distribution in determining extinction risk.     

Behavioural profiles of inbred mouse strains used as transgenic backgrounds. II: cognitive tests

One of the characteristic manifestations of several neurodegenerative diseases is the progressive decline in cognitive ability. In order to determine the suitability of six mouse strains (129S2/Sv, BALB/c, C3H/He, C57BL/6j, CBA/Ca and DBA/2) as transgenic background strains, we investigated the performance on a variety of tasks designed to identify subtle changes in cognition. In addition, a test of exploratory behaviour was used to probe the level of underlying anxiety in these mouse strains, as anxiety can be a confounding factor on behavioural performance generally. The C3H/He mice exhibited the least anxiogenic behavioural profile spending most time on the open arms of the maze, in contrast to the 129S2/Sv mice which spent the least amount of time in this location and were the quickest to move into a closed arm. The C3H/He mouse strain failed to acquire a visual discrimination task and failed to demonstrate learning on a water maze spatial learning task, in contrast to the CBA/Ca, DBA/2 and C57BL/6j strains which demonstrated a degree of learning in both tasks. No significant strain differences were identified on the object recognition task. These data, taken together, suggest that care must be taken when choosing cognitive tasks to be used with particular mouse strains and that task sensitivity must be considered as a critical element to research protocols with regard to these mouse strains.     

Biodiversity and biodiversity conservation in Yunnan, China

Yunnan, an inland province at a low latitude and high elevation, lying between 21°09–29°15 N and 97°32–106°12 E in southwestern China, has a vast territory with diversified and unique nature resources. There are more than 18000 high plant species (51.6% of China's total) and 1836 vertebrate species (54.8% of China's total) living in Yunnan on a land area of 39.4 × 10⁴km², i.e., only 4.1% of China's total. Among 15000 seed plants found in Yunnan there are 151 rare and endangered plant species (42.6% of China's protected plants). Out of 335 China priority protected wild animals, Yunnan has 243 species, accounting for 72.5% of China's total, 15% of which are species endemic to Yunnan. However, Yunnan's biodiversity is faced with the menace of excessive exploitation of resources and changes in environmental conditions caused by the activities of an expanding human population. This paper discusses the background, the composition, and the structure of Yunnan's biodiversity. Its biodiversity fragility and the threatened situation are also discussed. Suggestions and recommendations on the strategy and actions of Yunnan biodiversity conservation and sustainable development are proposed.     

Increased noise sensitivity and altered inner ear MENA distribution in VASP−/− mice

Vasodilator-stimulated phosphoprotein (VASP) and mammalian-enabled protein (MENA) share similar cellular localisation and functions (signal transduction pathways, regulation of actin cytoskeleton dynamics). Functional substitution and compensation among Ena/VASP proteins have been proposed as the reason for the absence of major morphological and functional deficits in VASP–/– mice. The aim of this study was to investigate VASP expression in the mouse cochlea, to analyse cochlear function in VASP–/– mice compared with wildtype mice, and to analyse cochlear MENA distribution taking into account that MENA protein might compensate VASP loss in the cochlea of VASP–/– mice. We confirmed specific VASP expression in the pillar cells of the mice organ of Corti as previously reported for rat cochlea. By analysing the hearing function in VASP–/– mice, we found no differences in auditory brainstem responses and distortion product otoacoustic emissions from those of wildtype mice but evidence for an increased noise sensitivity at lower frequencies. When MENA protein levels in cochlea tissue were tested in mutant and wildtype mice by Western blot analysis, no significant differences were found, as was also seen with regard to MENA mRNA levels in laser-microdissected single pillar cells. Most surprisingly, however, MENA protein was absent in pillar cells of VASP–/– mice, whereas it was detected in other cochlear cells. The finding of a cell-specific, and not organ-specific, redundancy of MENA protein expression noted for the first time in VASP–/– mice is proposed as the reason for the observed distinct cochlear phenotype.     

TNF/LTα double knockout mice display abnormal inflammatory and regenerative responses to acute and chronic liver injury

Following acute liver injury, hepatocytes divide to facilitate regeneration. However, during chronic injury, hepatocyte proliferation is typically blocked and repair is mediated through liver progenitor (oval) cells. Signalling of the p55 tumour necrosis factor (TNF) receptor is central to these processes. Two ligands for p55 are known: TNF and lymphotoxin-alpha (LT). However, one study suggests that another exists that mediates liver injury following viral challenge. We have therefore investigated whether ligands other than TNF and LT are required for liver regeneration following either acute or chronic injury. Wild-type and double TNF/LT knockout (TNF^–/–LT^–/–) mice were subjected to either partial hepatectomy (PHx) or a choline-deficient ethionine-supplemented (CDE) diet. Proliferating hepatocytes, oval cells and inflammatory cells were identified and quantified in liver sections by immunohistochemistry. Liver inflammatory cells were characterised by cell surface antigen expression. Liver damage and mortality were monitored. Both hepatocyte and oval cell proliferation was reduced in TNF^–/–LT^–/– mice. Lymphocyte clusters were evident in all TNF^–/–LT^–/– livers and were heterogeneous, comprising B and T lymphocytes. PHx evoked liver inflammation in TNF^–/–LT^–/– but not wild-type mice, whereas no difference was apparent between genotypes in CDE experiments. Thus, TNF/LT signalling mediates liver regeneration involving both hepatocytes and progenitor cells. The hyper-inflammatory response following PHx in TNF^–/–LT^–/– animals, which is absent following CDE-induced injury, demonstrates that the two forms of liver injury evoke discrete inflammatory responses and provides a model in which such differences can be examined further.     

Locally differentiated cryptic pigmentation in the freshwater isopod Asellus aquaticus

A repeated pattern of background colour matching in animals is an indication that pigmentation may be cryptic. Here, we examine the relationship between pigmentation of the freshwater isopod Asellus aquaticus and background darkness in 29 lakes, wetlands and ponds in Southern Sweden. The results show that Asellus pigmentation was correlated with substrate darkness across all localities. In seven localities, in which two contrasting substrate types were noted, Asellus populations were differentiated with respect to pigmentation. These findings thus provide phenomenological support for cryptic pigmentation in Asellus. Pigmentation generally increased with body size, but the relationship between pigmentation and size differed among localities, possibly as a result of differences in correlational selection on pigmentation and size. Selection thus appears to have resulted in local differentiation over a small spatial scale, even within lakes and wetlands. This differentiation is a likely cause behind elevated phenotype variation noted in localities with two substrate types, suggesting that habitat heterogeneity promotes genetic diversity.     

标记辅助导入的原理与应用

标记辅助导入是分子遗传信息应用于动物育种的一个重要方面, 其目的是在标记信息的辅助下将一个品种(供体)中的一个或多个优良基因导入另一个品种(受体), 同时还要尽可能地保持受体群体原有的遗传背景。在标记辅助导入过程中, 标记信息既可用于辅助前景选择, 即对目标基因携带者的选择, 以保证目标基因的正确导入, 也可用于辅助背景选择, 即对受体基因组的选择, 以加快受体遗传背景的恢复。本文介绍了标记辅助导入的原理和基本方法, 综述了目前已提出的不同前景选择和背景选择方法以及消除遗传累赘(与目标基因连锁的不利基因)的方法, 同时列举了标记辅助导入在动物上的一些成功应用。     

X射线和ENU诱变的Adh基因对黑腹果蝇醇耐受性的杂合效应

为研究部分显性的机制,用１２个黑腹果蝇醇脱氢酶（ＤＡＤＨ）基因内无效突变（Ａｄｈ＾ｎ）体作为材料。这些已知序列伯突变体「包括单碱基置换或基因内小段缺失（９￣１６个碱基）」,用来分析肽的合成,二聚体的形成和杂二聚体酶活性。杂合体中酶的部分表达和很广范围显性表达（从几乎完全陷性到高度显性）具多重机制。在１０％乙醇的高度胁迫下,所有１２个Ａｄｈ＾ｎ型果蝇中都观察到醇耐受性的部分显性表达。无效「突变表达的