共查询到20条相似文献,搜索用时 62 毫秒
1.
中国水螅属一新种(水螅纲,水螅科) 总被引:1,自引:0,他引:1
报道采自广东省肇庆市的淡水水螅1新种,多形水螅Hydra polymorphus sp.nov.,研究标本均来自1只水螅的单系繁殖群体,测量数据经生物统计学处理。新种的钩刺丝囊外形及内部刺丝盘旋均有多种形态,故新种名以此命名。所有研究标本保存于深圳大学生命科学学院。 相似文献
2.
3.
4.
5.
记述采自北京地区水螅属1新种:北京水螅Hydra beijingensis sp.nov.。新种的主要鉴别特征是出现体部与柄的分化;钩刺丝囊内刺丝缠绕具有2种形态:大部分钩刺丝囊(占2/3左右)内顶端基部刺丝呈4~5圈横向弹簧状缠绕,而占所观察刺丝囊总数1/3左右的囊内刺丝为不规则缠绕和纵向缠绕。标本保存在哈尔滨师范大学生命与环境科学学院生物学系无脊椎动物研究室。 相似文献
6.
中国水螅属一新种(螅形目,水螅科) 总被引:1,自引:0,他引:1
记述水螅科水螅属1新种:哈尔滨水螅Hydra harbinensis sp.nov.。本种与其它已报告的雌雄同体水螅有明显区别,只与美洲的海曼水螅较为相似,但也有不同,其与海曼水螅的区别为:生活于静水,能直立并可横向附着生活,实验室培养用储放的自来水可正常生活及生殖。粘刺丝囊小型。胚鞘的鞘膜表面有网格,每根圆锥形的棘刺发自每一网格中央,棘刺无结节,不分叉。精巢数目为2~6个,卵为4~6个。模式标本保存于哈尔滨师范大学生命与环境科学学院生物学系无脊椎动物研究室。 相似文献
7.
五种水螅基因组DNA的RAPD多态性研究 总被引:1,自引:1,他引:1
利用RAPD技术对水螅科2属5种水螅进行了基因组DNA多态性研究.80个随机引物筛选出18个引物,共扩增出303个清晰稳定的DNA片段,分子量在0.3~3.0kb之间.以UPGMA聚类法构建树状图,阐明水螅属种的分类关系:大庆水螅Hydra daqingensis、北京水螅H.beijingensis和强壮水螅H.robusta 3种分成两组并聚在一起;不同属的漠河水螅H.mohensis和绿水螅Chlorohydra sp.聚为一支;由此2属5种水螅分为两个支系. 相似文献
8.
9.
腔肠动物具有其他动物所没有的特殊的刺细胞(cnidocyst),因而旧称刺胞动物(Cnidaria)。刺细胞来源于未分化的间细胞,发育过程很复杂(图1见封二,下同)。成熟的刺细胞一般呈椭圆形,端部的一侧具一小针状的刺针(cnidocil),细胞核位于细胞的基部。刺细胞中含有一囊状的细胞器称刺丝囊(nematocyst)(图2)。在腔肠动物中已识别出的刺丝囊有20余种。Weill(1923)研究了 相似文献
10.
11.
The effects of cell crowding on the blastogenic response to phytohaemagglutinin in in vitro cultures of lymphocytes from both normal subjects and from patients with lymphoproliferative disorders were studied. Moderate degrees of cell crowding resulted in enhancement of blast transformation; however, further increases in the degree of crowding produced relative or absolute inhibition of blast transformation, an effect which was more marked in the normal controls than in the lymphoproliferative group. The significance of these findings is discussed. 相似文献
12.
Melville C. Watson 《CMAJ》1937,37(4):337-340
13.
Abstract— Acetylcholinesterase (AChE) and pseudocholinesterase (°ChE) were studied in vivo and during the first several months of development of pectoral and posterior latissimi dorsi (PLD) muscles in normal and dystrophic chickens. Muscle extracts were prepared in a high ionic strength-nonionic detergent medium in the presence of protease inhibitors, in order to obtain complete solubilization and to prevent degradation of intrinsic molecular forms of both enzymes. In both normal and dystrophic pectoral muscles levels of AChE and °ChE increase rapidly in vivo, °ChE accounting for 5–10% of total cholinesterase activity. In the normal pectoral muscle the concentration of both enzymes drops rapidly after hatching with increasing muscle mass; total AChE per muscle remains relatively constant for 30 days post-hatch. In the dystrophic pectoral muscle both AChE and °ChE accumulate after hatching, resulting in greatly elevated levels (approx 10–25-fold) of both enzymes throughout the period studied. Multiple molecular forms of AChE and °ChE are observed in the pectoral muscle by sucrose gradient centrifugation. Four principal forms are distinguished: two light (L1, L2), one medium (M), and one heavy (H2). The °ChE forms are 0.5–1.0 S units lighter than the corresponding AChE forms. L2 is the predominant light form of AChE, whereas L1 is the major light °ChE form detected. The lighter forms of AChE predominate in normal and dystrophic embryonic pectoral muscle at day 14, being replaced by the H2 form by day 19. H2 is the major °ChE form detected at day 19. After hatching, H2 AChE is the predominant form found in both of the normal muscles studied. In the dystrophic pectoral muscle, progressive accumulation of the L2 form of AChE is detected as early as day 4 post-hatch; this form eventually becomes predominant, although the heavier forms are also elevated. In PLD muscle the same phenomenon occurs, but with a slower time course. In dystrophic pectoral muscle a similar rise in the L1 form of °ChE is first observed by day 4, with heavier forms also elevated in the mature muscle. Thus the alteration in the control of these two enzymes in dystrophic fast-twitch muscles results in an accumulation of the light forms of AChE and °ChE. 相似文献
14.
15.
16.
17.
Justin J. Stein 《The Western journal of medicine》1960,92(3):189-193
The ratio of physicians to general population in California has been approximately the same for many years, the influx of physicians having kept pace with the population trend.For many years California has licensed more physicians than any other state.The five medical schools in this state have been increasing the number of candidates admitted to the freshman class. Attempts are being made to increase the number of medical schools in this state to seven in anticipation of the future growth and medical needs of the population.The heaviest concentration of physicians is as always in the thickly populated areas as determined by the population physician ratio.A study of the detailed statistics presented in this paper should be of interest to all California physicians. 相似文献
18.
19.
20.
GENETIC ANALYSIS OF DEVELOPMENTAL MECHANISMS IN HYDRA I. SEXUAL REPRODUCTION OF HYDRA MAGNIPAPILLATA AND ISOLATION OF MUTANTS 总被引:1,自引:0,他引:1
Hydra magnipapillata strains collected from various localities in Japan were induced to reproduce sexually.
From the survival data of the progeny, it was calculated that H. magnipapillata contained an average of between 3.5 and 4.0 lethal equivalent units of recessive deleterious genes per gamate (between 7.0 and 8.0 per animal).
Various types of developmental mutants were found among the offspring of crosses made between strains isolated from the same ponds. The mutant types isolated included mini strains, maxi strains, multi-headed strains, nematocyst-deficient strains, regeneration-deficient strains and male sterile strains. The characters of these strains were stably transmissible to the successive progeny produced by budding. These strains therefore were propagated by budding and maintained as clonal lines to be used later for developmental studies. 相似文献
From the survival data of the progeny, it was calculated that H. magnipapillata contained an average of between 3.5 and 4.0 lethal equivalent units of recessive deleterious genes per gamate (between 7.0 and 8.0 per animal).
Various types of developmental mutants were found among the offspring of crosses made between strains isolated from the same ponds. The mutant types isolated included mini strains, maxi strains, multi-headed strains, nematocyst-deficient strains, regeneration-deficient strains and male sterile strains. The characters of these strains were stably transmissible to the successive progeny produced by budding. These strains therefore were propagated by budding and maintained as clonal lines to be used later for developmental studies. 相似文献