Paravannella minima n. g. n. sp. (Discosea,Vannellidae) and distinction of the genera in the vannellid amoebae

Paravannella minima n. g. n. sp. (Amoebozoa, Vannellidae) isolated from a freshwater aquarium, possesses all light-microscopic and ultrastructural characteristics of the genus Vannella, being one of the smallest species among the vannellid amoebae (cell size during locomotion usually between 4.5 and 10 μm). At the same time, sequence analysis of the genes encoding for nuclear SSU rRNA, actin and mitochondrial Cox1 shows this species as the earliest-branching vannellid that appears to be sister to the rest of this clade. This is correlated with the presence of some plesiomorphic characters; in particular, the secondary structure of the hypervariable helices E23-1–E23-7 in the studied species is shared with Vannella and most of the genera of Dactylopodida. The cell coat structure of the studied species corresponds to the hypothesis that vannellid amoebae were ancestrally enclosed in a cell coat consisting of pentagonal glycostyles that have undergone multiple independent losses in various clades of Vannellidae.     

The fine structure of conidial development in the genus Torula. II. T. caligans (Batista and Upadhyay) M. B. Ellis and T. terrestris Mistra.

Conidia of Torula caligans (Batista & Upadhyay) M. B. Ellis comb.nov. and T. terrestris Misra were examined by transmission- and scanning-electron microscopy. Torula caligans produced four-celled conidia in which the central cells were distinctly larger than the basal and apical cells. Conidia of T. terrestris were 4- to 7-celled long and ellipsoidal in shape. Conidiogenous cells in both species developed melanin only within the lowermost part of the lateral walls while the other cells of the conidium were uniformly melanized around the circumference of the cell; melanin in these cells being deposited within, at least, half the width of the cell wall. In both species new conidia arose from evagination of the hyaline apex of the conidiogenous cell and are therefore blastoconidia. The systematic relationships between T. caligans and T. terrestris and other species of the genus Torula are discussed.     

Leucocytozoon hamiltoni n. sp. (Haemosporida,Leucocytozoidae) from the Bukharan great tit Parus bokharensis

A new species of Leucocytozoon with gametocytes in fusiform host cells is described from the Bukharan great tit Parus bokharensis. It represents the first leucocytozoid in which the host cell nucleus is split into 2 more or less symmetrical portions, each located at an end of the host cell within its elongated fusiform processes. This species appears to be restricted with respect to geography and host.     

Organization of the teleostean nucleus rotundus.

The nucleus rotundus of 21 species of teleosts was studied by a modified Bodian and the Golgi method to clarify the histological organization, with special reference to the cell lamination and the glomerular formation. The common components of the nucleus in all species are as follows: a thick fiber bundle which comes from the commissura horizontalis and enters the nucleus from the dorsal surface, many small cells, large cells, glomeruli, and a surrounding fibrous capsule. The nuclei of all species studied are classified into three types mainly on the distribution of the small cells, and to a lesser degree on the location of the large cells and the glomeruli. The first type of nucleus has small cells, large cells and glomeruli throughout its extent. In the second type of nucleus, many small cells form a peripheral cell layer, while the large cells and glomeruli are found all over the nucleus. The third type of nucleus is clearly laminated. It is composed of four layers arranged concentrically around a central fiber net in the following order: a glomerular layer, a fibrous layer, a small-cell layer, and a peripheral fibrous capsule. In some species, the large cells are located in the fibrous capsule, and all glomeruli contain a star-like structure, which corresponds to the tips of the large cell dendrites.     

The Use of the A.P.I. Lactobacillus System for the Characterization of Pediococci

A commercially produced system for the identification of Lactobacillus , by which the reactions of concentrated cell suspensions towards 50 substrates may be determined, is useful for the characterization of strains of Pediococcus . Suitable conditions for inoculum preparation vary for slow and fast growing strains; the influence of cell concentration on the results is described. The reactions are classified in terms of their value for species characterization and the results are shown to agree well with those in other studies where classical procedures have been used.     

Survival of freeze-dried bacteria.

The aim of this study was to investigate the survival of freeze-dried bacterial species stored at the International Patent Organism Depository (IPOD) and to elucidate the characteristics affecting survival. Bacterial strains were freeze-dried, sealed in ampoules under a vacuum (<1 Pa), and stored in the dark at 5 degrees C. The survival of a variety of species following storage for up to 20 years was analyzed. The survival of freeze-dried species was analyzed in terms of two stages, freeze-drying and storing. Nonmotile genera showed relatively high survival after freeze-drying. Motile genera with peritrichous flagella showed low survival rates after freeze-drying. Vibrio and Aeromonas, which produce numerous flagella, showed very low survival rates. In Lactobacillus, non-trehalose-fermenting species showed better survival rates after freeze-drying than did fermenting species, and those species with teichoic acid in the cell wall showed lower survival rates during storage than species with teichoic acid in the cell membrane. Human pathogenic species of Corynebacterium, Bacillus, Streptococcus, and Klebsiella showed lower survival rates during storage than nonpathogenic species within the same genus. Among Pseudomonas species, P. chlororaphis, the only species tested that forms levan from sucrose, showed the lowest survival rate during storage in the genus. Survival rates of Gram-negative species during storage tended to be lower than those of Gram-positive species, though Chryseobacterium meningosepticum had stable survival during storage. The conclusion is that smooth cell surfaces (i.e., no flagella) and lack of trehalose outside the cytoplasm improved survival rates after freeze-drying. Because desiccation is important for survival during storage, the presence of extracellular polysaccharides or teichoic acids is disadvantageous for long-term survival. The lower survival rates of freeze-dried Gram-negative bacteria compared with those of Gram-positive bacteria may be attributed to the thinner peptidoglycan layer and the presence of lipopolysaccharides on the cell wall in the former species.     

Cross-reactive T-cell antigens among mammalian species.

Fluoresceinated heteroantisera prepared against T cells of rats, monkeys, and humans were reacted withthymus and spleen cells from 11 selected species. These reagents recognized cross-reacting T cell antigen(s) among rodent species (mouse, rat, guinea pig, and hamster) and among primate species (monkey and humans). With one exception, the cross-reactivity was restricted to a phylogenetic order. All three antisera required relatively few absorptions to achieve T cell specificity for related species when compared to absorption requirements for the isologous species. Differentiation antigens within a phylogenetic order thus appear to be more homologous than other cell surface constituents on T cells.     

Systematics of the genus Ceratopteris Brongn. (Parkeriaceae) II. Taxonomy

A revision of the genusCeratopteris is presented based on comparative morphology and geographical distribution. Four species are recognized:C. thalictroides, C. cornuta, C. pteridoides, andC. richardii. Characteristics of taxonomic importance include frond length, shape, and dissection; stipe width; insertion of basal pinnae; bud development; habit; annulus cell number; spore number per sporangium; spore size; and spore surface features. Evolution within species and putative hybridization between species are discussed.     

Key to the species of Hyphozyma (yeast-like Hyphomycetes) and description of H. roseonigra sp. nov.

The new species, Hyphozyma roseonigra, characterized by pink colonies, budding cells with minute annellated zones and brown, septate hyphae, is described. It is non-fermentative, shows no colouration with Diazonium Blue B, and has an ascomycete-type cell wall ultrastructure. A key to the accepted species and varieties of Hyphozyma is given.     

新疆天山一号冰川地区12种藓类植物叶形态结构研究

采用石蜡切片和扫描电镜的方法,对新疆天山一号冰川地区的12种藓类植物叶片结构及叶表面微形态进行了观察。结果显示,不同苔藓植物叶细胞、中肋、细胞壁、细胞表面等各项指标在类型、大小、分布、干燥时细胞壁的凹陷程度以及表面角质层纹饰和小孔形态、分布等都明显不同,这些微形态特点不仅在藓类植物属下种间的区分上具有分类学意义,同时也反映出藓类植物叶片为保水抗旱,抵御长期寒冷、多风和强光照射等恶劣环境对其的伤害而形成的生存策略。本研究结果为苔藓植物在极端环境地区的生态学功能研究提供了重要的科学依据。     

Systematics of two deep-water species from the Indo-West Pacific: Struvea gardineri A.Gepp & E.Gepp and Phyllodictyon orientale (A.Gepp & E.Gepp) Kraft & M.J.Wynne (Siphonocladales, Chlorophyta)

Two rare and ill-known subtidal species of stalked, net-forming green algae, Struvea gardineri A.Gepp & E.Gepp and Phyllodictyon orientale (A.Gepp & E.Gepp) Kraft & M.J.Wynne, are re-described on the basis of the examination of type material and recent collections from the Maldives, Seychelles, and Socotra Island in the tropical Indian Ocean. The taxonomic position of both species is re-appraised on the basis of morphological data (cell division, branching pattern, tenacular cells, crystalline cell inclusions, cell shape, and cell dimensions) and molecular phylogenetic evidence (partial large subunit nuclear ribosomal DNA sequences). On the basis of the occurrence of segregative cell division in young plants of S. gardineri , this species is returned to its original genus, Struvea . Cell division in P. orientale takes place exclusively by centripetal wall ingrowths, confirming its placement in the genus Phyllodictyon as currently defined. However, morphological observations and molecular phylogenetic studies indicate that the delineation of genera on the basis of modes of cell division is problematic, and that the genera Struvea and Phyllodictyon , as presently conceived, almost certainly do not represent natural groups.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 115–132.     

Steady-state methods for the study of placental exchange.

Published and new data on steady-state exchange of tracers and oxygen are characterized by marked species differences. When the placenta is treated as an ideal diffusion cell of unknown vessel geometry and permeability, the exchange characteristics of oxygen can be used to prove that the exchange of tracers such as acetylene, nitrous oxide, tritiated water and antipyrine is entirely flow limited. The recorded patterns of transfer of flow-limited tracers reveal that some placentas are as effective as counter-current exchangers whereas others mimic the behavior of the less effective types of exchangers. These species differences in apparent geometry are unrelated to the histologic nature of the barrier. The patterns of flow-limited transfer are so similar to those of oxygen transfer that the diffusion resistance to oxygen must be small. The exchange of diffusion-limited (hydrophilic) tracers mimics exchange across capillary membranes in some species and exchange across cell membranes in others. These species differences in diffusion-limited transfer are clearly related to the histologic nature of the barrier and are independent of vessel geometry.     

GnRH-systems in the forebrain of cichlid fish.

The neuronal systems that contain gonadotropin-releasing hormone (GnRH) were quantitatively examined in the forebrain of two cichlid species (Oreochromis niloticus Lin. and Tilapia maria Boulenger) using tracing methods and immunostaining. In both species the nucleus olfacto-retinalis and a population of neurons in the basal preoptic region contained GnRH. The nucleus olfacto-retinalis was divided into several neuronal subpopulations which differed with respect to cytology, projection pattern, and peptide content. GnRH cell number increased with body size, the rates being different for the different subpopulations. A sexual dimorphism was found in the basal preoptic region of Tilapia; males had significantly fewer GnRH-containing cells than females. Selective staining of the basal preoptic region demonstrated that this cell group is the main source of GnRH-innervation of the pituitary gland and indicate that the molecular forms of GnRH expressed in the two cell populations studied may be different.     

Cyclic AMP accumulation in HeLa cells induced by cholera toxin. Involvement of the ceramide moiety of GM1 ganglioside.

The influence of ceramide composition on the rate of GM1 association to HeLa cells has been investigated by incubating the cells in the presence of either native ganglioside or molecular species carrying highly homogeneous long chain base moieties, fractionated from native GM1. The GM1 ganglioside species carrying the unsaturated C18 long chain base moiety proved to have the fastest rate of association, whereas the saturated species carrying 20 carbon atoms had the slowest rate. After having increased the GM1 cell content (65-fold) by incubation with the various ganglioside species, the cells were incubated with cholera toxin and the time course of cyclic AMP accumulation was monitored. Remarkable differences among cells enriched with the various molecular species were found in the duration of the lag time preceding the accumulation of cyclic AMP, the shortest being displayed by the unsaturated C18 species. Moreover, the amount of cyclic AMP accumulated after a given time of incubation with cholera toxin was significantly higher when the C18:1-GM1 species was present than with native GM1. Fluorescence anisotropy experiments, carried out using the probe 1,3-diphenylhexatriene, show that the GM1 ganglioside ceramide moiety was also modifying the cell membrane fluidity of the host.     

Human complement factor H. Tissue specificity in the expression of three different mRNA species.

Using cDNA clones H-19 and H-46, we have shown previously that three different mRNA species (4.3 kb, 1.8 kb and 1.4 kb) for complement factor H are expressed constitutively in human liver. Here we report data suggesting that the expression of these different factor-H mRNA species is regulated by tissue-specific control mechanisms. Total RNA and poly(A)-enriched RNA from various human tissues (heart, lung, temporal cortex, kidney, spleen, bone marrow and muscle) various cell lines (HepG2, HepG3, HepG4, Hep3B, H-4, Jurkat, Molt4, H-9, KHos24Os, A-431, U937, Mono Mac 6 and Raji) and from primary cultures of peripheral blood monocytes, fibroblasts and human umbilical vein endothelial cells (HUVEC) were investigated for the expression of factor-H mRNA. In RNA preparations from extrahepatic tissue, factor-H mRNA was only detected in biopsies from the lung. Using 20 micrograms total RNA isolated from all 13 cell lines it was not possible to detect any factor-H mRNA, while mRNA for factor H was expressed in monocytes, HUVEC and fibroblasts. When expressed in extrahepatic tissues, only the 4.3-kb and the 1.8-kb mRNA species were detected, while the 1.4-kb mRNA is expressed abundantly in liver. Interferon-gamma did not induce the expression of factor-H mRNA in any of the cell lines tested. On the other hand, tumour necrosis factor-alpha induced the expression of the 4.3-kb mRNA species in U937 cells. In HUVEC and fibroblasts the relative quantities of the 4.3-kb and the 1.8-kb mRNA species and the regulatory effects of interferon-gamma, interleukin-1, dexamethasone and retinoic acid on their expression showed significant tissue specificity.     

Ultrastructural localization of pancreatic polypeptide in the F cell of the dog pancreas.

The F cell of the dog pancreas has been identified as the specific cell type containing pancreatic polypeptide. This localization of pnacreatic polypeptide was accomplished by immunocytochemical staining of ultrathin sections and direct electron microscopic identification. Verification of the specificity of the reaction was obtained by blocking experiments on serial sections of the same cell. It is proposed that the name F cell be used for defining in all species the islet cell that contains pancreatic polypeptide.     

Alterations in lysine transfer RNA during erythroid differentiation of the Friend cell.

The proportion of lysine tRNA represented by the isoacceptor species lysine tRNA4 has previously been shown to be largest in cells with the greatest ability to proliferate. Using reverse phase chromatography (RPC-5), we have analyzed the changes in the relative quantities of lysine tRNA species which occur in different cellular states of the Friend cell, a transformed murine cell infected with Friend erythroleukemia virus complex. This cell undergoes erythroid differentiation when exposed to various chemicals. Lysine tRNA4 comprises 32% of the total lysine tRNA in rapidly dividing, uninduced Friend cells, but only 16% of the total lysine tRNA in uninducase. Friend cells undergoing erythroid differentiation divide more slowly than uninduced cells, and finally cease proliferation, but lysine tRNA4 becomes the major lysine tRNA species (greater than 50%). This does not appear to reflect erythroid properties of the cell, since the lysine tRNA of the mouse reticulocyte contains very little lysine tRNA4. The non-dividing erythroid Friend cell, therefore, represents an exception to the finding that non-dividing cells usually have little or no lysine tRNA4 present.