Distribution of Pax6 protein during eye development suggests discrete roles in proliferative and differentiated visual cells

 Although Pax6 is required during eye development in rodents and humans, little is known about the precise role of the protein in this process. To aid in the interpretation of functional studies, we have determined the precise spatial and temporal distributions of the Pax6 protein in the eye. We find that Pax6 is initially distributed contiguously throughout a large domain of the anterior neural plate of zebrafish, including the presumptive eye fields and the dorsal diencephalon. After evagination of the optic vesicle, Pax6 becomes restricted to all proliferating cells of the pigment epithelial and neural layers of the retina. Pax6 is downregulated in most cells concomitant with differentiation. However, it remains present in several mature cell types of the eye including amacrine cells and the lens and corneal epithelia. This expression is conserved across diverse vertebrate species and suggests that Pax6 has additional conserved functions in the mature eye. Received: 27 August 1996 / Accepted: 21 October 1996     

蚕豆在重金属污染条件下数量性状的分化研究

运用正交设计方法,经过４代的原位种植实验,研究了在人工控制条件下Ｐｂ＾２＋、Ｃｄ＾２＋、Ｈｇ＾２＋、Ｚｎ＾２＋对同一蚕豆种质在株高、首次开花时间、每株结豆荚数、单位豆荚豆数数（每２０个豆荚）、种子的重量（５０粒）等数量性状的代内和代间分化,实验结果表明,在初始种植代仙,低深度的重金属除使开花时间以外的各数量性状指标程度不同有刺激升高作用;高浓度则使性状明显受到抑制。对于属除使开花时间以外的各数量性     

Preadipocyte Recruitment in Stromal Vascular Cultures After Depletion of Committed Preadipocytes by Immunocytotoxicity

Glucocorticoids or the glucocorticoid analog dexamethasone (DEX) enhances the differentiation of preadipocytes in the presence of insulin and influences preadipocyte proliferation. The purpose of the present study was to determine if DEX can induce the recruitment of preadipocytes. Using monoclonal antibodies for complement-mediated cytotoxicity, preadipocytes were removed from porcine stromal vascular (S-V) cell cultures. Our experiments demonstrated for the first time that after removal of preadipocytes by cytotoxicity, preadipocytes or fat cells could be induced by DEX or DEX plus insulin but not by insulin alone. However, many more fat cells were induced (258 ± 15/unit area) when DEX was added with fetal bovine serum (FBS) followed with insulin treatment, compared to DEX with insulin (21.3 ± 5.1/ unit area) after removal of preadipocytes. Immunocyto-chemistry with AD-3, a preadipocyte marker, showed that DEX with FBS for 3 days after seeding (i.e., the proliferation phase) produced many more preadipocytes (AD-3 positive, 223 ± 45/unit area) than FBS alone (10.5 ± 1.4/unit area). Bromodeoxyuridine (BrdU) incorporation assays demonstrated that the efficiency of DEX with FBS (i.e., during proliferation) was mitosis dependent. Accordingly, we conclude that: porcine S-V cultures contain preadipocytes at different stages of differentiation and that DEX induced early preadipocyte differentiation depends on mitosis.     

The ecology of ruffe,Gymnocephalus cernuus (Pisces: Percidae) introduced to Mildevatn,western Norway

Synopsis Diet, habitat use, diel and seasonal activity and a number of population parameters were studied on ruffe,Gymnocephalus cernuus, introduced to Mildevatn, western Norway. This lake is sited outside the natural range of the ruffe and has a lower fish diversity and a different fish species composition than within its native range. From June through September the ruffe was planktivorous and mainly caught at 4 to 6 m depth in the benthic zone. At other times of year ruffe was feeding on zoobenthos and caught deeper in the benthic zone. Ruffe was mainly day active. Zooplankton feeding during summer is the clearest difference compared to ruffe populations living within its natural range. Presence of large zooplankton organisms available for ruffe is suggested as the main reason for the difference found in food choice. The availability of large zooplankton is probably due to community structure caused by a predator and lack of interspecific competition for zooplankton in the deeper parts of the lake. Piscivorous brown trout.Salmo trutta, restrict the habitat of threespined stickleback,Gasterosteus aculeatus, to the zone of littoral vegetation, allowing high densities of larger zooplankton species likeBythotrephes longimanus to be present in the lake. Brown trout is present only in the upper light and well oxygenated parts of the lake, leaving a refuge for the ruffe, where they can feed on the rich zooplankton community.     

Genetic differentiation in Hippocrepis emerus (Leguminosae): allozyme and DNA fingerprint variation in disjunct Scandinavian populations

The structure of genetic variation in disjunct Scandinavian populations of Hippocrepis emerus was studied using allozymes and DNA fingerprinting. Variation in the three native regional populations in Scandinavia was compared with that in a recently introduced population in Sweden. In contrast to the recently introduced population, the native Scandinavian isolates of H. emerus showed high levels of allozyme fixation and low levels of DNA diversity. Variation in allozymes and at DNA fingerprint loci showed closely congruent patterns of geographic variation, with pronounced differentiation between the native Norwegian and Swedish isolates of the species. The structure of genetic variation in native Scandinavian H. emerus is interpreted in terms of historical population bottlenecks and founder events during the species' postglacial immigration into Scandinavia.     

Mitochondrial DNA products among RAPD profiles are frequent and strongly differentiated between races of Douglas-fir

Racial differentiation and genetic variability were studied between and within the coastal, north interior, and south interior races of Douglas-fir using RAPD and allozyme markers. Nearly half of all RAPD bands scored (13:45%) were found to be amplified from mitochondrial DNA. They exhibited maternal inheritance among hybrids and back-crosses between the races, and were much more highly differentiated (G_ST= 0.62 for haplotype frequencies) than were allozymes (G_ST= 0.26). No evidence of hybridization or introgression was detected where the coastal and interior races come into proximity in central Oregon.     

高原鼠兔与达乌尔鼠兔食物资源维生态位的研究

作者于１９９３年在青海省刚察县年诺索玛地区发现高原鼠兔（Ｏｃｈｏｔｏｎａ ｃｕｒｚｏｎｉａｅ）和达乌尔鼠兔（０．ｄａｕｒｉｃａ）在布哈河谷二阶同域且重叠分布之现象,并从这两种鼠兔的食物资源利用出发,研究了其生态位关系问题。在食物资源维上的生态位宽度（ＰＳ）,高原鼠兔为０．４７４４,达乌尔鼠兔为０．４９６４,即它们具有相近似的生态位宽度。这两种动物的生态位在食物资源谱维上的重叠值（ＦＴ）为０．８０９     

喀喇昆仑、昆仑山地区植物元素含量的区域分异和数量分析

对喀喇昆仑、昆仑山地区87种植物21个元素含量及区域分异的研究表明,Ca、Cr、Cd、Fe、V含量比高等植物含量偏高,Ph、P的含量偏低。同种植物在不同地点元素含量有差异。盐柴荒漠植物中Na、K、Mg、P含量较高;高山草甸、冰缘植被植物Ba、Ca、Fe、V、Ti含量较高。各植被类型植物元素含量Na/K差异最大,Ca/Mg较小,Fe/Al差异最小。其变异系数分别为153.5、20.5和15.9.%