METHYLTESTOSTERONE-INDUCED DIFFERENTIATION OF A SEMINAL VESICLE HOMOLOGUE IN JUVENILE GOLDFISH, CARASSIUS AURATUS L.

In male goldfish, a structure homologous to the seminal vesicles of other fishes develops from the posterior sterile region of testicular ridges coincidentally with the initiation of spermatogenesis in the anterior region. Sexually differentiated juvenile goldfish were administered with methyltestosterone (50 μg/g diet) for a period of 20 days from 40 (experiment I) and 60 days (experiment II) after hatching. In both experiments, androgen administration exerted inhibitory influences on germ cell development in both sexes, but rather promoted the formation of the ovarian lumen, and of its residues in male gonads as well, accompanied with columnar hypertrophy and ciliation of the epithelium. The same treatment brought about a prominent development of the seminal vesicle homologues in the caudalmost gonadal ridges of females as well as in those of males in experiment II but not in experiment I. The cause of difference in the effects between the two experiments seemed to be ascribable to an incomplete prolongation of the gonadal ridges up to the presumptive area of the organ at the start of experiment I. Thus the capacity of the seminal vesicle primordia, common to both sexes, to make their due differentiation in response to exogenous androgen is confirmed in this study.     

Morphology and biology of Polysaccus japonicus (Crustacea, Rhizocephala, Akentrogonida, Polysaccidae, fam. n.), a parasite of the ghost-shrimp Callianassa japonica

The morphology and biology of Polysaccus japonicus Høeg & Lützen, 1993 is described. Nearly all infected hosts are adults, the females of which become castrated. Each bears 4–50 (female) externae on the underside of the abdomen. The externae are interconnected via a root system within the host's perineural blood sinus. The externae pass through three moults. Cypris larvae inject spermatogonia into the immature externa's mantle cavity, which is where spermiogenesis occurs later. Multiplication of the male cells is probably supported by secretion from paired mantle cavity glands, presumably homologous to the receptacles of kentrogonid rhizocephalans. Late during the 2nd intermoult the visceral mass ruptures to release the ova into the mantle cavity where they become fertilized. The third moult results in opening of the mantle aperture which initiates a period of vigorous peristalsis of the muscular mantle. Following emission of the cypris larvae the externae perish leaving distinct scars. The root system always contains buds of various sizes and stage of development. When the scarred host moults, the most advanced buds emerge to give rise to a new generation of externae. This is thought to be repeated for the rest of the host's life.
The antennule of the cyprid has a relatively very long and slender 3rd segment, a unique construction among Akentrogonida. Because of this and the presence of special mantle cavity glands, a new family, Polysaccidae, is erected, which in some characters is intermediate between the Kentrogonida and the Akentrogonida.     

Ultrastructure and Rapid Axopodial Contraction of a Heliozoa, Raphidiophrys contractilis Sp. Nov.

ABSTRACT. In the present study, we isolated a species of heliozoans from a brackish pond in Shukkeien Garden, Naka-ku, Hiroshima City, Japan. Electron-microscopic observations showed that the axonemal microtubules in this heliozoan constituted a complex pattern of hexagons and triangles. By applying SDS-polyacrylamide gel electrophoresis and subsequent immunoblotting, molecular weights of α and β-tubulins were determined to be 48 and 45 kDa, respectively. X-ray microanalysis demonstrated that the numerous scales coating the cell body surface were silicic structures. Size and shape of the cell body and the scales were examined and compared with other known species of heliozoans, which led us to conclude that this is a new species belonging to the genus Raphidiophrys . This heliozoan was also found to carry out rapid axopodial contraction during food uptake at a velocity of about 1 mm/s. With reference to this characteristic contractile behavior, this new species was named Raphidiophrys contractilis .     

A comparative study on insemination dependency of circadian activity pattern in mosquitoes

Abstract. Two forms of mosquitoes in the Culex pipiens complex, C.p.pallens and C.p.molestus , were compared for the insemination-dependency of entrained female circadian activity in LD 16:8h. When virgin, Pallens is nocturnal and molestus is, in addition, diurnal. Insemination and injection of extracts of the male accessory gland affects virgin activity in that nocturnality is strengthened in both mosquitoes, and the diurnal activity of molestus is depressed. This was so whether the treatments were intra- or interspecific. These findings are compared with those already published for other mosquitoes. A coherent view is proposed that the mosquito, nocturnal/crepuscular, nocturnal and diurnal, or diurnal, has potentially a similar entrained waveform which is affected by insemination in a common way, and by lighting conditions in species specific ways.     

Scanning Electron Microscopic Study of the Initial Phase of Encapsulation in Samia cynthia ricini

When a piece of cellulose acetate membrane (CEA) was implanted into the haemocoel of a full-grown larva of Samia cynthia ricini , a number of haemocytes became attached to it and extended cell processes. These cells all lysed within 4 min after implantation, with the appearance of a fibrous network on and near the tips of the processes. The network increased with inclusion of cell debris and finally coated the implant completely. Extensive lysis of spheroidal cells was seen on the outside of the network formed 20–60 min after implantation, together with flattened cells which were accumulating to form a capsule. The relationship of cell lysis and network formation is discussed.     

Microsatellite loci for the weaver ant Oecophylla smaragdina

We developed 13 microsatellite loci in Oecophylla smaragdina from random amplified polymorphic DNA (RAPD) fragments. These loci showed two to 14 alleles in O. smaragdina with expected heterozygosity of each locus from 0.10 to 0.89, and six were also polymorphic in the related species, O. longinoda. The results suggested that the loci will be useful to analyse the genetic structure of Oecophylla species at both the colony and population levels.     

The role of olfactory cues in the sequential radiation of a gall‐boring beetle,Mordellistena convicta

1. Herbivorous insects often have close associations with specific host plants, and their preferences for mating and ovipositing on a specific host‐plant species can reproductively isolate populations, facilitating ecological speciation. Volatile emissions from host plants can play a major role in assisting herbivores to locate their natal host plants and thus facilitate assortative mating and host‐specific oviposition. 2. The present study investigated the role of host‐plant volatiles in host fidelity and oviposition preference of the gall‐boring, inquiline beetle, Mordellistena convicta LeConte (Coleoptera: Mordellidae), using Y‐tube olfactometers. Previous studies suggest that the gall‐boring beetle is undergoing sequential host‐associated divergence by utilising the resources that are created by the diverging populations of the gall fly, Eurosta solidaginis Fitch (Diptera: Tephritidae), which induces galls on the stems of goldenrods including Solidago altissima L. (Asteraceae) and Solidago gigantea Ait. 3. Our results show that M. convicta adults are attracted to galls on their natal host plant, avoid the alternate host galls, and do not respond to volatile emissions from their host‐plant stems. 4. These findings suggest that the gall‐boring beetles can orient to the volatile chemicals from host galls, and that beetles can use them to identify suitable sites for mating and/or oviposition. Host‐associated mating and oviposition likely play a role in the sequential radiation of the gall‐boring beetle.     

Conservation of electron transport and energy transfer reactions of spinach chloroplasts in glycero

When spinach chloroplasts were suspended in 50% glycerol inthe presence of 5 mM sodium chloride, then stored at –20°Cactivity of the Hill reaction was retained for several monthswith a small loss. Under these conditions photophosphorylationactivity was reduced by half during the month of storage. (Received February 2, 1971; )     

Red and far-red reversible photoreactions on seed germination of Cucumis sativa

The effects of red and far-red light in seed germination ofCucumis sativa differs markedly with the degree of seed ripeningand the variety of seed; reciprocal hybrids are clearly maternal. (Received December 26, 1968; )