Fatty Acid and Chlorophyll Levels of Coastal Bermudagrass during the Day and during Maturation

Lipids were extracted from fresh, field-grown coastal bermudagrass (Cynodon dactylon (L.) Pers.) and the fatty acids determined by gas chromatography. Total fatty acid levels (dry weight basis) increased during the day and reached a single maximum at sunset in 2-week-old grass; whereas, in older grass, the fluctuations in fatty acid levels showed two maxima. The first maximum occurred 4 h after sunrise and the second maximum occurred at sunset. Total fatty acid levels, based on dry weight, decreased during the first 6 weeks of growth and changed very little after an additional 4 weeks' growth in bermudagrass leaf blades. Chlorophyll levels (dry weight basis) continuously decreased during the entire growth period (10 weeks). Chlorophyll alb ratios increased at sunset in 2- and 6-week-old grass, but this ratio did not change during the day in subsequent growth stages. The results of these experiments show that stages of maturity affected fatty acid fluctuations during the day as well as total fatty acid and chlorophyll levels in Coastal bermudagrass leaf blades. Chlorophyll alb ratios varied independently of fatty acid levels.     

A Role of Calcium Ions in Chemical Induction of Mating in Paramecium tetraurelia*

SYNOPSIS. Conjugation in Paramecium tetraurelia can be induced within mating-reactive cultures of a single mating type by treating the cells with solutions of KC1 + acriflavine in culture medium low in Ca²⁺. Gene mutations with known physiologic effect were used as selective inhibitors of cell surface membrane function to see which functions are necessary for chemical induction of conjugation. The results strongly suggest that a transient increase in the internal concentration of calcium at the very beginning of chemical induction is a necessary but not sufficient step.     

Notes on the biology of Trypanosoma ambystomae Lehmann, 1954. II. The Life Cycle in the Invertebrate Host.

SYNOPSIS. The leech, Erpobdella sp., is a suitable invertebrate host for Trypanosoma ambystomae. The developmental cycle involves a mononucleate, rounded body derived from the bloodstream form; this body then transforms into a large plump crithidia. Subsequent divisions yield medium crithidia, small crithidia, and ultimately, metacyclic trypanosomes.     

Natural Variants of the Cellular Slime Mold Acrasis rosea

SYNOPSIS. Twenty different isolates of the cellular slime mold Acrasis rosea, obtained from diverse sources and geographic regions, were studied to determine similarities and differences in their development and structure in culture and their sensitivity or resistance to selected chemicals incorporated into the culture media. Six different classes of fruiting were defined based on the size, distribution, and type of sorocarps formed on the yeast, Rhodotorula, streaked on agar. In the course of these studies a significant mutant, NC-18V (variant), developed spontaneously from the wild type, normal parent strain NC-18N. The mutant differed considerably from all other Acrasis isolates, appeared several times in purified parental cultures, and represents the first laboratory derived variant of A. rosea to be described. Purified strains of the variant (V) and normal (N) cultures were obtained by single-spore isolation. Normal and variant amebae were mixed in ratios of 10:1 and 100:1 (N:V) and spore and stalk cells were selected from different sorocarps in various regions of the culture plate for analysis. The results of these selection experiments clearly indicate that the individual variant amebae have increased migratory ability and that they develop smaller, morphologically different, and more numerous sorocarps that form at distances further from the food source than NC-18N. Some isolates of Acrasis no longer were able to fruit and were classified as “non-fruiters” and a few other isolates formed only a few, small sorocarps on rare occasions. These isolates were mixed together in various combinations of 2 and 3 to screen for cell interaction, but no synergism contributing to fruiting was found. Although fruiting of many A. rosea isolates was inhibited by exposure to continuous light or constant darkness, some “escape”fruiting was noted in certain isolates even when small inocula were used. Single spore isolates of these escape fruiters still fruited in continuous light or dark, but fruiting was always greatly enhanced by a routine 12 hr light : 12 hr dark incubation cycle. It was shown by biochemical studies that actidione, crystal violet, malachite green, ethyl violet, and 5-fluorodeoxyuridine selectively killed some isolates and permitted a classification of isolates as either sensitive or resistant. In a further study of cell interaction between 2 different sets of Acrasis isolates with contrasting biochemical and morphologic markers the formation of neotypes or recombinants could not be demonstrated. The results of this study clearly indicate the existence of significant variation in A. rosea and the potential for application of these differences to developmental studies.     

Sperm structure and ultrastructure in the Hymenoptera (Insecta)

A light and electron microscopical survey of spermatozoan gross morphology and ultrastructure in the Hymenoptera is presented. Details are provided for the first time for members of the families Xyelidae, Argidae, Tenthredinidae, Diprionidae, Cephidae, Figitidae, Proctotrupidae, Diaprii- dae, Heloridae, Eurytomidae, Leucospidae, Perilampidae, Torymidae, Braconidae, Dryinidae, Sphecidae, Pompilidae and Vespidae. Spermatozoan length ranged from 8 μ m in some Braconidae to 500 μm in one chalcidoid. Considerable variation in gross morphology and ultrastructure were observed between taxa. Several phylogenetically informative characters were noted. Very small spermatozoa characterized most of the non-cyclostome subfamilies of Braconidae; spirally twisted axoneme and mitochondrial derivatives occur in the Eulophidae, Eurytomidae and Pteromalidae; spermatozoa with virtually indistinguishable head (nucleus and acrosome) regions characterized the Vespinae and Polistinae. The presence of well-developed spermatodesmata in the vas deferens and seminal vesicle characterize the Symphyta and were largely absent from other groups though they are occasionally present in some bees.     

1-M1-甲基环丙烯和氯化钙处理对鲜切西瓜果实脂质水解酶的作用(英文)

无籽西瓜(Citrullus　lanatus　Thunb.　Mansfeld,　cv.　Millionaire)果实在10　μL/L　1-甲基环丙烯(1-MCP)或正常空气中预贮18　h后,切取内果皮肉柱　(直径7　mm,长40　mm),再用2%　CaCl2或去离子水冲淋肉柱,然后将肉柱贮藏于10　℃。测定贮藏过程中的果肉硬度、电导率、磷脂酶D　(PLD)、磷脂酶C　(PLC)和脂氧合酶　(LOX)的活性变化。结果显示,2%　CaCl2刺激PLD、PLC和LOX的活性,维持果肉的硬度。单独用CaCl2处理并不足以维持切割西瓜的品质,还可能因刺激脂质水解酶而发生不良的作用。1-MCP能够抵抗CaCl2对PLD、PLC和LOX的刺激作用。与对照相比,1-MCP与CaCl2结合处理能延缓西瓜果肉的衰老过程,表现出较高的果肉硬度和较低的脂质水解酶活性。     

Systematics of the Neotropical braconid wasps of the Pedinotus genus group (Doryctinae)

The braconid subfamily Doryctinae (Hymenoptera) is a cosmopolitan, species‐rich group of parasitoid wasps whose known species richness and morphological diversity is mainly concentrated in the Neotropical region. Among the doryctine taxa that are endemic to this region, there is a group of six genera (the Pedinotus genus group) that are mainly characterized by having lateral, posteriorly converging or subparallel grooves on the second metasomal tergite (including Gymnobracon Szépligeti, Hybodoryctes Szépligeti, Lamquetia Braet et van Achterberg, Osmophila Szépligeti, Pedinotus Szépligeti and Trigonophasmus Enderlein). Most of these genera were described more than a century ago, and thus their limits and diagnostic morphological features are not well defined. We present an analysis of the phylogenetic relationships among various representative species of five of the six genera belonging to the Pedinotus genus group based on one mitochondrial (cytochrome oxidase I) and two nuclear (28S, Wingless) gene markers. We also estimated the timing of origin and diversification within the group and investigated the external morphology of the genera involved in order to determine reliable identification characters. The group as a whole, whilst being recovered as monophyletic with the inclusion of Acanthorhogas Szépligeti, was not statistically supported. However, the respective monophyly of all of the morphologically supported genera are confirmed, as are the intergeneric relationships (Gymnobracon, Trigonophasmus) ((Acanthorhogas, Osmophila) (Lamquetia, Pedinotus)). We propose that the pattern of sublateral grooves or depressions appears to be a useful systematic character for recognition of an endemic Neotropical radiation that could have originated c. 41–27 Ma. We redescribe six of the seven genera that we recognize for the Pedinotus genus group and provide a key to enable their identification.     

Coccidia from the Tiger Salamander, Ambystoma tigrinum, in Northeastern Colorado and in Northern New Mexico

SYNOPSIS. Oocysts of Eimeria ambystomae Saxe, 1955, Eimeria microcapi sp. n., and Eimeria urodela sp. n. are described from the tiger salamander, Ambystoma tigrinum , collected in Colorado and New Mexico. The oocysts of E. ambystomae are ellipsoid, 29.8 × 17.3 (24–38 × 15–25) μm, and the sporocysts lanceolate, 22.6 × 5.4 (16–27 × 5–7) μm. Oocyst and sporocyst residua are present, but not a polar granule and a micropyle. The oocysts and sporocysts of E. microcapi are ellipsoid, measuring respectively 38.1 × 25.3 (35-41 × 23-26) μm and 18.1 × 7.4 (16-19 × 6–8) μm. Oocyst and sporocyst residua, a micropyle (mean 3 μm), and a distinct micropyle cap (2 μm high) are present, but not a polar granule. The oocysts of E. urodela are spheroid, 22.2 (14-26) μm, and the sporocysts lanceolate, 16.3 × 5.8 (12-19 × 4-7) μm. Oocyst and sporocyst residua are present, but a polar granule and a micropyle are absent.