广西九万山藓类植物区系分析及其对划分热带,亚热带分界线的意义

九万山位于广西北部的中央(25°10’～25°25’N,108°27’E),界于泛北极植物区和古热带植物区的交汇处。其主要植被为亚热带常绿阔叶林。最高海拔为1693m,最低处仅170m。经对1850号标本的鉴定,共计有藓类植物35科、101属和189种。本文分析了九万山的藓类植物区系成分,将其划分为 10种类型。其中东亚成分最为丰富(39.33％),热带、亚热带成分次之(38.20％),而温带成分居第三位(18.54％)。本文选择了九万山临近的五个地区加以比较。其中,金佛山与九万山藓类植物的属和种的相似性系数分别为60.68％和36.87％,神农架为57.29％和33.13％。尖峰岭为48.83％和22.29％,西双版纳为57.29％和29.63％。而我国东部的武夷山则为69.86％和39.57％,其相似性系数在相比较的五个山区中为最高。九万山区有4个特有属并明显受喜马拉雅的影响。特别值得注意的是,在九万山区藓类区系中约有7％的种类是典型的热带成分。根据定量和定性的分析,笔者认为九万山的藓类区系表现出由热带向亚热带过渡的特性,其分界线可能位于九万山的南侧。     

Dioecy in the endemic genusDendrocacalia (Compositae) on the Bonin (Ogasawara) Islands

Dendrocacalia crepidifolia Nakai (Compositae, Senecioneae), the only species of this arboreal genus endemic to Haha Island in the Bonin Islands, was found to be dioecious. Male flowers differ from female ones in having a stunted style (style in female exserted from corolla and deeply bifurcating) and anthers filled with fertile pollen (anthers in the female lacking pollen). The size of the corolla and number of florets per head were similar between male and female flowers. The crown area of this arboreal species was also similar in male and female plants. The sex ratio was 0.55 male, not significantly different from 0.5. Both sexes produced nectar of similar sugar concentration (ca. 50%). The flowers are pollinated by feral honeybees (Apis mellifera), but they are thought to have been pollinated by small, lesshairy, endemic solitary bees before honeybees were introduced and subsequently became the dominant bee species on the island. The evolution of dioecy ofDendrocacalia on the island is thought to stem from the deleterious effects of inbreeding that are inherent in plants with geitonogamy. The increased geitonogamy on the island has resulted from increased woodiness (i.e., increased number of flowers per plant) and the original dependence on endemic bee pollinators, which are now endangered.     

Pflanzenvergesellschaftungen mit Riccia-Arten in Südwestafrika (Namibia)

Three associations of the Nanocyperion teneriffae Lebrun 1947 (Sporoboletalia festivi Lebrun 1947) are described. They are physiognomically and ecologically similar to associations of the Mediterranean Isoeto-Nanojuncetea Br.-Bl. et Tx. 1943 and Helianthemetalia guttati Br.-Bl. 1940. They are rich in very specialized therophytes and resurrection plants.

Meinem Lehrer H. Walter, Stuttgart gewidmet.     

Cryopreservation of Plasmodium chabaudi. II. Cooling and warming rates

Various cooling and warming rates were investigated to determine the optimum conditions for cryopreserving the intraerythrocytic stages of Plasmodium chabaudi. Infected blood, equilibrated in 10% v/v glycerol at 37 degrees C or in 15% v/v Me2SO at 0 degree C for 10 min, was cryopreserved using cooling rates between 1 and 5100 degrees C min-1. After overnight storage in liquid nitrogen the samples were warmed at 12,000 degrees C min-1. Warming rates between 1 and 12,000 degrees C min-1 were investigated using samples previously cooled at 3600 degrees C min-1. After thawing, the glycerol and Me2SO were removed by dilution in 15% v/v glucose-supplemented phosphate-buffered saline. Survival was assayed by inoculation of groups of five mice each with 10(6) infected cells and the time taken to reach a level of 2% parasitemia estimated. The optimum cooling rate was 3600 degrees C min-1 for parasites frozen using either 10% glycerol or 15% Me2SO; the pre-2% patent periods were 0.90 and 1.01 days above control values (representing survival levels of 21 and 17.5%, respectively). The optimum warming rate was 12,000 degrees C min-1; the pre-2% patent periods were 1.01 and 1.32 days above control values, respectively (18 and 10% survival), for glycerol and Me2SO. With ethanediol (5% v/v) and sucrose (15% w/v) as cryoprotectants the optimum warming rates were also 12,000 degrees C min-1 while the optimum cooling rates were 330 and 3600 degrees C min-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Principal-components analysis of prehistoric South Asian crania

Principal-components analysis is used as an investigative procedure for establishing temporal, spatial and evolutionary-developmental changes in Homo sapiens skeletal specimens from prehistoric sites in South Asia. It is concluded that cranial variables which cluster hunter-gatherers within the sample are related to facial architecture with respect to robusticity and size. Older models presumably reflecting genetic affinities and racial classifications of prehistoric South Asians which were based upon univariate-bivariate statistical analyses are not supported by the results of this principal-components analysis.     

Glucose-6-phosphate dehydrogenase porbandar: A new slow variant with slightly reduced activity in a South African family of Indian descent

A new variant of the red cell enzyme glucose-6-phosphate dehydrogenase has been detected in a South African male of Indian descent and in several of his relatives. The enzyme variant is characterized by slow electrophoretic mobility, low Michaelis constants for the substrates glucose-6-phosphate and NADP, and increased utilization of the substrate analogues 2-deoxyglucose-6-phosphate and deamino-NADP relative to the normal (B⁺) enzyme. There is no evidence that the enzyme variant, for which the name G6PD Porbandar is suggested, is associated with any hematological abnormality.The Atomic Energy Board and the South African Medical Research Council provided support for part of this work.     

A spectroscopic study of metal ion and ligand binding to β-lactamase II

β-Lactamase II has two metal-binding sites. The electronic spectra of Cd(II)- and Co(II)-substituted β-lactamase II have been investigated. It is suggested that a thiol ligand is involved in metal binding at the first site. The stoichiometric dissociation constants for Co(II) binding to β-lactamase II were estimated to be 0.13 and 2.66 mM (pH 6.0, 4°C, 1 M NaCl) by equilibrium dialysis. Competition between Zn(II) and Co(II) for the first metal binding site suggests a value of 0.7 μM (pH 6.0, 30°C, 1 M NaCl) for the dissociation constant o Zn(II).The electronic spectra of the Co(II) enzyme lead to the suggestion that the coordination geometries around the metal ions in the first and second sites are related to those of a distorted tetrahedron and octahedron, respectively.     

Comparison of phospho- and dephospho-ATP citrate lyase

The dephospho- form of rat liver citrate lyase has been prepared by treating purified [³²P]-ATP citrate lyase with a partially purified phosphatase. A comparison of the properties of the phospho- and dephosphoenzyme has been performed. The pH optima were the same for both forms of the enzyme in four different buffer systems although the optimum values varied identically for both enzyme forms with the buffer. Both the phospho- and dephosphoenzymes show the same kinetic properties except for the K_m observed for ATP in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer system where it was 54 μm for the phosphoenzyme and 292 μm for the dephosphoenzyme. The present study also indicates that both enzymes are cleaved by trypsin and lysosomal proteases in a similar manner. Both forms of the enzyme tend to associate with mitochondria to the same extent and both enzymes have identical temperature stability curves.     

Studies on plating efficiency and estimation of viability of suspensions of Paracoccidioides brasiliensis yeast cells

Mild sonication was used to obtain single cell suspensions of Paracoccidioides brasiliensis. These cells were intact by microscopic criteria. Direct cell counts in a given inoculum and colony formation on various media were used to determine plating efficiency. Sonicated and nonsonicated cell suspensions were used to study plating efficiency and to estimate viability by means of vital dyes. Methylene blue, Erythrosin B, and Janus green were unreliable when used with P. brasiliensis, but vital dyes were accurate when tested with Candida albicans.Acridine orange gave more meaningful results of viability. Estimates of viability, however, changed significantly as a result of relatively minor alterations in the composition of the suspending medium.In initial experiments, the plating efficiency of P. brasiliensis was dismally low. It descended abruptly with increasing dilution of inoculum. Efficiency was much improved if horse serum was added to brain heart infusion plates or if glucose glycine yeast extract (GGY) plates were incubated at room temperature and mycelial colonies were counted. With the technique we report, current plating efficiency of sonicated suspensions is of the order of 25 %. Our results and procedures have an important bearing upon those studies concerned with in vitro killing of P. brasiliensis in suspensions or with isolating this fungus from clinical or environmental specimens.     

Cellular immunity to Coccidioides immitis: In vitro lymphocyte response to spherules,arthrospores, and endospores

In vitro stimulation of incorporation of tritiated thymidine by human peripheral lymphocytes in response to two soluble antigens and three different intact but nonviable fungal forms of Coccidioides immitis was studied. Lymphocytes were obtained from three groups of subjects: healthy skin test positive, healthy skin test negative, and disseminated disease. Dose-response relationships to the intact forms (endospores, arthrospores, and spherules) were determined. Responses of lymphocytes from healthy skin test-positive subjects and subjects with disseminated disease were similar. Ranking of antigens by “potency” gave the following results: endospores = spherulin > mycelial filtrate > arthrospores = spherules. Endospores were the most potent of the intact forms in 10 of 11 subjects. The clear superiority of endospores over spherules is not due to differences in the total particle surface area available for presentation to the leukocytes. All antigens tested except spherules could discriminate between skin test-positive and skin test-negative subjects in this in vitro system. A T-cell-enriched, B-cell- and mono-cyte-depleted cell population demonstrated an active response to spherulin and to endospores. The variance of these finding with animal studies demonstrating spherules to be immunogenically superior when compared to endospores is discussed. This may have importance in future studies in humans of vaccines to C. immitis.