Effects of Succinyl Concanavalin A and Tunicamycin on F9 Embryonal Carcinoma Cells: Inhibition of Cell Spreading

Succinyl concanavalin A at a concentration of 50 μg/ml inhibited spreading of F9 embryonal carcinoma cells, while at this concentration it inhibited cell growth only partially. Thus, in the presence of succinyl concanavalin A, F9 cells grew as rounded cell aggregates that sometimes became detached from the substratum. Tunicamycin at a concentration of 1 μg/ml had a similar effect on F9 cells. These results suggest that a mannosyl glycoprotein(s) is involved in cell-substratum interaction of the cells. Furthermore, tunicamycin partially inhibited the biosynthesis of embryoglycan, the large glycoprotein-bound carbohydrates of early embryonic cells.     

Isolation of polymorphic microsatellite loci in Hemerocallis fulva and Hemerocallis citrina (Hemerocallidaceae)

Twenty microsatellite loci were isolated from a hybrid of two daylilies, Hemerocallis fulva and Hemerocallis citrina. We characterized individuals from two H. fulva populations and two H. citrina populations in Japan and observed three to 20 alleles per locus in H. fulva and one to 19 alleles per locus in H. citrina. Mean observed heterozygosity within populations ranged from 0.35 to 0.85 in H. fulva and from 0 to 0.95 in H. citrina. In about a half of the loci, the observed heterozygosity did not deviate from Hardy–Weinberg equilibrium. These loci are proved useful in studying gene flow and qualitative trait loci mapping using the two species.     

Abundance of Naked Amoebae in Sediments of Hiroshima Bay, Seto Inland Sea of Japan

ABSTRACT The present paper provides the first data on naked amoebae from sediments of Hiroshima Bay. Three stations in the inner part of the bay were sampled over a three-month period. Abundance of naked amoebae ranged from 1,019 to 45,561 cells/g dry sediment. Results indicate: (i) surface sediment populations in most cases were higher than subsurface populations; (ii) there was some evidence of temporal variation with counts generally increasing from March to May: and (iii) the site located near Hiroshima City had fewer amoebae on several occasions than the other two sites. There was a negative exponential relationship between acid-volatile sulfide concentration and abundance of amoebae. Most amoebae were small with the average size ranging from 6.6–14 μm. Morphotype 1, amoebae that extend lobose pseudopodia or subpseudopodia during normal locomotion, were dominant (40–100% of enumerated amoebae). Morphotypes 2 and 3 (limax amoebae) were found in lower numbers than the other two morphotypes. The proportion of amoebae occupied by Morphotype 4 (fan-shaped or discoidal-flattened amoebae) was higher at a lower total abundance.     

SCANNING ELECTRON MICROSCOPIC STUDY ON THE SURFACE CHANGE OF EGGS OF THE TELEOST, ORYZIAS LATIPES, AT THE TIME OF FERTILIZATION

The surface change of the egg of the teleost, Oryzias latipes , during fertilization was observed with a scanning electron microscope. The microvilli of the outer surface of the unfertilized egg show a slight difference in density between the animal and vegetal pole areas. In the initial step of the breakdown of cortical alveoli (CA), several small holes or gapes are formed at the apical part of the CA membrane, becoming a large aperture from which the alveolar contents are discharged. The formation of microvilli is observed on the inner surface of the exposed cavity left by the CA, starting from the periphery of the aperture and propagating throughout the whole inner surface in accompaniment with the release of the alveolar contents. After the completion of CA breakdown, the CA membrane cannot be distinguished from the original egg plasma membrane.     

ANALYSIS OF CELL PROLIFERATION DURING EARLY EMBRYOGENESIS

Cell proliferation was examined during early embryogenesis of the newt ( Triturus pyrrhogaster ) by various methods. After the two-cell stage, at 23°C, the blastomere (cell) number per whole embryo increased logarithmically until the mid-blastula stage (for about 19 hr) and the rate of increase slowed down in and after the late blastula stage. On the other hand, the synchronous cleavage of the blastomeres at the animal pole continued for 18 hr until the twelfth cleavage (mid-blastula) and the transition from synchronous to asynchronous division occurred abruptly at and after the thirteenth cell division (late blastula). The study also showed that the presumptive neuro-ectoderm consisted mainly of cells of the fifteenth generation (G-15) at the onset of gastrulation (pigment stage).
The present study suggested that the number of ectodermal cells of the early gastrula (stage 12a) nearly doubled during gastrulation at the presumptive neuro-ectoderm. This means that most of the ectodermal cells are in G-16 at the end of gastrulation. On the other hand, both mitotic activity and the rate of cell increase gradually diminished during gastrulation in the ectoderms of both the presumptive neural and epidermal regions, and there are evidently significant differences in both activities between the neuro-ectoderm and the epidermal ectoderm after stage 13b: the epidermal ectoderm showed greater decrease in the rate of both mitotic activity and cell proliferation than the neuro-ectoderm.
These facts suggested that, whether the ectodermal cells will differentiate into neural cells or epidermal cells is determined during G-15 or G-16 in normal primary induction.     

Differentiation of Sea Urchin Micromeres: Correlation between Specific Protein Synthesis and Spicule Formation

Sea urchin micromeres were isolated from the 16-cell stage embryos and cultured until they differentiated into spicule-forming cells. Electrophoretic analysis of proteins labeled with [³⁵S]-methionine showed that the differentiation accompanied the synthesis of five cell-specific proteins. These proteins appeared prior to spicule formation and were synthesized continuously or maintained stably while the cultured micromeres formed spicules. In contrast, these proteins were hardly detectable during development of the meso- and macromeres. Correlation between synthesis of the specific proteins and spicule formation was further examined in culture conditions which inhibit spicule formation. In Zn²⁺ -containing or serum-free medium, the micromere descendants failed to form spicules and exhibited markedly reduced synthesis of one of the specific proteins (32 K daltons). After removal of Zn²⁺, or addition of serum, however, spicules were formed with delay but concomitantly with an increase in the synthesis of this protein. This clear correlation suggests the participation of the 32 K protein in the process of spicule formation.     

Green leaves enhance the growth and development of a stream macroinvertebrate shredder when senescent leaves are available

1. Freshly fallen green leaves and flowers of terrestrial plants enter temperate streams in spring and summer, when senescent leaf litter is often scarce. These resources appear to provide good supplementary food for macroinvertebrate shredders, but have some potential shortcomings as food or case material for caddisflies. 2. To compare suitability of green leaves or flowers and senescent leaves for the growth and development of stream shredders, we reared the caddisfly Lepidostoma complicatum in the laboratory with treatments that provided larvae with senescent (oak) and green (oak or maple) leaves separately, and also together, in case the combined use of both types of leaf may benefit the shredder. 3. Larvae supplied with green leaves alone grew at 65% of the rate of those provided with senescent leaves alone, due to their lower consumption rate. No individuals given green leaves alone developed into adults, whereas 70% of the individuals given senescent leaves alone did. Green leaves may inhibit larval consumption due to their high phenol content, or they may be unsuitable for case material because they are less tough than senescent leaves. 4. Larvae supplied with both senescent and green leaves (or flowers) had a higher growth rate and developed faster, than those given senescent leaves alone, whereas the proportions of successfully emerged individuals did not differ. Lepidostoma probably benefits from the higher nitrogen content of the green leaves when used together with senescent leaves. 5. These results suggest that green leaves (or flowers) cannot serve as an alternative food resource to senescent leaves, but that they can enhance the growth and development of a Lepidostoma stream shredder if senescent leaves are also available.     

A new anhydrobiotic midge from Malawi,Polypedilum pembai sp.n. (Diptera: Chironomidae), closely related to the desiccation tolerant midge,Polypedilum vanderplanki Hinton

The sleeping chironomid (Polypedilum vanderplanki Hinton) lives on temporary rock pools in the semi‐arid tropical regions of Africa. Its larvae are able to survive the dry season in a completely desiccated ametabolic state known as anhydrobiosis. So far, P. vanderplanki was the only species among all insects showing demonstrated anhydrobiotic ability. Here, we show that a new related species originating from Malawi, Polypedilum pembai sp.n. , is also anhydrobiotic and that its desiccation tolerance mechanism is probably similar to what is observed in P. vanderplanki. The new species, P. pembai sp.n. , is described with special attention to the common and different morphological features, compared with P. vanderplanki. Phylogenetic analysis showed that both species are closely related, suggesting that anhydrobiosis evolved only once in their common ancestor about 49 Ma somewhere in Africa, before the divergence of two species, one in the sub‐Saharan area and another in southeastern Africa.