THE DISTRIBUTION AND ABUNDANCE OF DEEPWATER MACROALGAE IN CENTRAL CALIFORNIA

Silvetia compressa ( J. Agardh) Serrão et al. is a common member of the upper intertidal fucoid community on the Pacific coast of America from Humboldt County, California, to Punta Baja, Baja California, Mexico. A relatively narrow range of morphological variability is exhibited by most mainland populations, regardless of latitude, but some mainland populations and all insular populations participate in a complex pattern that we have attempted to analyze. A few populations on the Monterey Peninsula in which the fronds are atypically delicate were described by Setchell & Gardner as f. gracilis , to which was assigned a population from Santa Catalina Island. After comparing populations from various parts of the range of the species, including all of the Channel Islands, we conclude that two subspecies may be recognized. In subsp. compressa , which includes f. gracilis as a growth form and occurs chiefly on the mainland, the frond is robust with long tapered receptacles. In the variant subspecies, which is chiefly insular but also occurs on the coast of northern Baja California, the typical frond has slender axes as in f. gracilis , but is more densely branched and has short ellipsoidal receptacles. Comparison of nucleotide sequences from the ITS regions of rDNA revealed an identical pattern for subsp. compressa from Baja California and central California, including populations assignable to f. gracilis. By contrast, the pattern for the variant subspecies differed by 2 bp (0.3%) from that of subsp. compressa.     

THE DISTRIBUTION OF COCCIDIOIDOMYCOSIS IN SOUTHERN CALIFORNIA

In coccidioidin skin test surveys among persons of high school age in Saugus, Canoga Park, Banning and Palm Springs areas the average incidence of positive reaction was 15 per cent. Although considerably less than the 68 per cent incidence reported among high school students of Kern County, it is high enough to indicate pockets of relatively high endemicity in Southern California below the San Joaquin Valley.Histoplasmin tests were performed on most of the persons tested with coccidioidin in this survey. The over-all incidence of positive reaction in the group was 7.6 per cent. Most of the subjects with positive reaction to histoplasmin gave a history of having previously lived in some area in the central United States where histoplasmosis is known to be endemic.A few subjects who had positive reaction to coccidioidin tests and who had lived in areas known to be endemic for coccidioidomycosis but not for histoplasmosis, also had positive reaction to histoplasmin. However, the induration produced was always smaller than that caused by the coccidioidin reaction, and there was minimal confusion in interpreting the tests.     

佛坪大熊猫的分布与数量

作者于1990年11—12月对佛坪自然保护区境内大熊猫的分布和数量进行了调查。结果得知在区内293平方公里中共有大熊猫64只,平均密度为0.22只/平方公里。与1974、1983、1988年3次的调查结果比较,表明佛坪大熊猫现有种群基本稳定。     

中国灰鹤的分布与数量现状

分析文献结合笔者的研究得知,除广东、广西、福建、海南、香港、澳门和台湾外,中国其余省区均有灰鹤分布,但目前分布的区域正在缩小;采用模糊数学思维对灰鹤进行种群数量测算,在20世纪与21世纪之交,我国灰鹤数量可能超出21632-22401只。     

金黄地鼠视觉中枢发育过程中P物质神经元数量及分布的变化

本实验用免疫细胞化学技术观察了不同年龄金黄地鼠视皮层和上丘中P物质(SP)阳性神经元数量和分布的变化,同时观察了不同年龄金黄地鼠视皮层SP阳性神经元的形态和类型。结果表明,出生后10天小鼠视皮层SP阳性神经元为36％,Ⅱ—Ⅳ层密度最大,约占40％。上丘中SP阳性神经元约为37％。出生后20天,视皮层及上丘中SP阳性神经元分别减少到23％和16％。视皮层Ⅱ—Ⅳ层减少最明显,Ⅴ层和Ⅵ层变化不大。成年鼠视皮层及上丘中偶见SP神经元,但出现一些SP阳性纤维。出生10天及20天鼠视皮层中SP阳性神经元的形态及类型没有差别。     

蚤类在宿主体表的分布及温度和蚤数的关系

本文研究了方形黄鼠蚤松江亚种Citellophilus tesquorum sungaris和二齿新蚤Neopsylla bidentatiformis在小白鼠体表的分布及环境温度和体表蚤数的关系.结果证明,在各种温度下,鼠背部蚤数均多于腹部.5℃时,鼠前部蚤数多于后部;10—20℃时,前部与后部蚤数相近;25—40℃时,后部蚤数多于前部.鼠后背部蚤数随温度升高而增多,前腹部蚤数随温度升高而减少;温度越高二者之差越大,说明温度越高蚤越向后背部集中.鼠体蚤数较少时,背部与腹部,前部与后部,蚤数差别明显;鼠体蚤数过多时,各部位蚤数无大差别.     

单眼剥夺对金黄地鼠视觉中枢GABA神经元分布的影响

用免疫细胞化学技术观察了单眼剥夺后金黄地鼠视觉中枢GABA神经元分布的变化。结果表明:单眼剥夺后,金黄地鼠视皮层和上丘的GABA阳性神经元暂时性增多,但剥夺后六个月,其数目显著减少。在单眼剥夺前和剥夺后侧膝体中GABA阳性神经元数目没有明显差异。剥夺眼对侧视皮层GABA阳性神经元数比剥夺眼同侧视皮层GABA神经元数目少。单眼剥夺后视觉中枢GABA神经元类型及形态与剥夺前没有差别。晚期单眼剥夺也能引起视觉中枢GABA神经元数量和分布的变化。以上结果表明,单眼剥夺后视觉中枢抑制神经元的结构发生了变化。     

SEASONAL PATTERNS IN THE ABUNDANCE AND DISTRIBUTION OF CALIFORNIA CETACEANS, 1991–1992

This study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100-150 nmi (185-278 km) of the California coast during 1991 and 1992. The results of a shipboard line-transect survey conducted in July-November 1991 ("summer") were compared to those from aerial line-transect surveys conducted in March-April 1991 and February-April 1992 ("winter"). Using a confidence-interval-based bootstrap procedure, abundance estimates for six of the eleven species included in the comparison exhibited significant (α= 0.05) differences between the winter and summer surveys. Pacific white-sided dolphins ( Lagenorhynchus obliquidens ), Risso's dolphins ( Grampus griseus ), common dolphins ( Delphinus spp.), and northern right whale dolphins ( Lissodelphis borealis ) were significantly more abundant in winter. The abundance of blue whales ( Balaenoptera musculuss ) and gray whales ( Eschrichtius robustus ) reflected well-documented migratory patterns. Fin whales ( B. physalus ) were significantly more abundant during summer. No significant differences in seasonal abundance were identified for Dall's porpoises ( Phocoenoides dalli ), bottlenose dolphins ( Tursiops truncatus ), killer whales ( Orcinus orca ), sperm whales ( Physeter macrocephalus ), or humpback whales ( Megaptera novaeangliae ). Significant north/south shifts in distribution were found for Dall's porpoises, common dolphins, and Pacific white-sided dolphins, and significant inshore/offshore differences were identified for northern right whale dolphins and humpback whales.     

西藏东南部金珠藏布流域虎的数量和分布现状

采用Ｆ检验和ｔ检验的方法,对西藏东南部金珠藏布流域野外收集的孟加拉虎足迹数据进行数理统计,统计结果得到虎的６个个体样本,结合在当地的大量访查工作,确证了该流域至少有５只虎的分布。另外嘎隆藏布流域发现１只虎的踪迹。金珠藏布流域虎的活动小区有一定重叠,说明它们可能存在一定的亲缘关系。对金珠藏布流域及邻近地区虎的活动情况也进行了调查,调查结果表明虎的分布和数量自７０年代以来呈减少趋势。     

洋葱细胞核中类胀泡结构的数目,体积和分布

在电镜下观察了洋葱（Ａｌｌｉｕｍ ｃｅｐａ Ｌ．）根端分生组织细胞核的连续切片并进行了三维重组。发现：１． 类胀泡结构在细胞核中的数目与二倍染色体数有较大差异。在所观察的Ｓ期细胞核中,该结构数为４—１０ 个;在所观察的Ｇ２ 期细胞核中,该结构数为４—９ 个。２． 类胀泡结构的体积变化比较大,大多数的体积在０．１—０．４ μｍ ３ 之间。不同的Ｓ期细胞核中,类胀泡结构总体积较大者是总体积较小者的１．８ 倍;不同的Ｇ２ 期细胞核中,类胀泡结构总体积较大者是总体积较小者的２．１ 倍。３． 类胀泡结构有集中分布在细胞核内一定区域的倾向。讨论了类胀泡结构是否为着丝粒等问题     

ORIGINS AND CONSEQUENCES OF SERPENTINE ENDEMISM IN THE CALIFORNIA FLORA

Habitat specialization plays an important role in the creation and loss of biodiversity over ecological and evolutionary time scales. In California, serpentine soils have a distinctive flora, with 246 serpentine habitat specialists (i.e., endemics). Using molecular phylogenies for 23 genera containing 784 taxa and 51 endemics, we infer few transitions out of the endemic state, which is shown by an analysis of transition rates to simply reflect the low frequency of endemics (i.e., reversal rates were high). The finding of high reversal rates, but a low number of reversals, is consistent with the widely hypothesized trade‐off between serpentine tolerance and competitive ability, under which serpentine endemics are physiologically capable of growing in less‐stressful habitats but competitors lead to their extirpation. Endemism is also characterized by a decrease in speciation and extinction rates and a decrease in the overall diversification rate. We also find that tolerators (species with nonserpentine and serpentine populations) undergo speciation in serpentine habitats to give rise to new serpentine endemics but are several times more likely to lose serpentine populations to produce serpentine‐intolerant taxa. Finally, endemics were younger on average than nonendemics, but this alone does not explain their low diversification.     

损伤视神经后斑马鱼视网膜神经节细胞数量和分布的变化

中枢神经系统的再生是神经科学领域的一个重要课题。鱼类和两栖类的视神经作为中枢神经系统的一部分,具有再生的能力。已知在损伤视神经后,对与视神经纤维直接相连的视网膜神经节细胞的形态结构,数量和分布等产生一系列的影响。视神经再生过程中细胞学研究在很大程度上依赖于示踪方法和其它技术的发展,结合光镜和电镜,它们仅对神经细胞末梢的精细结构和神经细胞间突触连接构筑等研究较准确详实,但对视网膜神经节细     

舟山岛中国小鲵种数量和分布的研究

舟山岛自１９８５年发现有中国小鲵分布后,作者于每年１２月至翌年５月小鲵繁殖期间,对岛上中国小鲵的种群数量和分布情况开展全面调查,表明其种群密度大,分布广泛、资源丰富。