摘要:

Experiments on glochidiosis of the freshwater pearl mussel,Chamberlainia hainesiana, were carried out using the fry of four species of fish, namely Temminck's kissing gourami (Helostoma temmincki), striped tiger nandid (Pristolepis fasciatus), walking catfish (Clarius macrocephalus) and sand goby (Oxyeleotris marmoratus). The fry were exposed to four concentrations of glochidia, and the LE50values (the concentrations that killed 50% of the fry) were determined. The most resistant species wasO. marmoratus, which also gave the highest production of juvenile mussels. Juveniles appeared 18–27 days after infection.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672347

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Immunohistochemistry was used to characterize central neurons which react to antibodies raised against neuropeptides known to control reproduction in other molluscs. Antibodies raised against αCDCP (α caudodorsal cell peptide) and CDCH (caudodorsal cell hormone), peptides which control ovulation in the pulmonate gastropodLymnaea, labelled numerous neurons inMytilus, MyaandPlacopecten.The labelled neurons in the cerebral and visceral ganglia ofMytilusare consistent with descriptions of neurons implicated in the control of reproduction on the bases of earlier neurosecretory staining procedures. This study thus suggests that related peptides might be involved in the reproduction of gastropods and bivalve molluscs. The use of selective immunological markers for peptides which might control bivalve reproduction not only permits the tentative identification of neurosecretory cells in bivalves but also suggests a promising avenue for future research aimed at isolating and characterizing neuropeptides involved in the control of reproduction in these molluscs.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672348

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The effects of eyestalk ablation, cheliped amputation, and rearing conditions on molt increment and scute density were studied in larvae of the lobsterHomarus americanus. Eyestalk-ablated larvae had higher percentage increases in carapace length (ZCL) but lower scute densities (SDs) in the molts to third and fourth stage. Cheliped amputation decreased ZCL but not SD. Third stage larvae raised in a circulating seawater system and fed a diet of adult brine shrimp resulted in higher ZCLs but normal SDs compared with those raised in a static system fed a diet of brine shrimp nauplii. We conclude that the growth-promoting effect of eyestalk ablation was mainly a result of the increased surface area of epicuticle produced by each epidermal cell and that the postmolt size of intact larvae was predetermined mainly by the number of epidermal cells present before molt.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672349

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The development ofGlossiphonia complanatatakes place in about 40 days. The young are attached to the parent's ventral side by means of their posterior sucker. At the time of hatching muscle cells are not recognizable. Therefore, the various morphogenetic steps of these round circomyarian fibers can be analyzed. The contractile material starts to be formed in a continuous peripheral ring encircling a central cytoplasmic core. Thus the round circomyarian condition is achieved from the very beginning. A comparison is made with the morphogenesis of muscle fibers in oligochaetes where an initial platimyarian condition is present. The formation of the gut in glossiphonids is completed in the last phases of embryonic development. When the young individual detaches from the parent some yolk store is still present in the gut diverticula. This condition is related to the peculiar trophic dependence of the young on the parent.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672350

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Features of the spermatozoon ofCalocarcinus africanuswhich are general for heterotremes and endorse its inclusion in the Heterotremata are: extension of the subacrosomal chamber almost to the anterior apex of the sperm, presence of an acrosome ray zone, and presence of a thickened ring where the capsule surrounds the base of the subacrosomal chamber. A feature shared with “higher” heterotremes is the restriction of cytoplasm to the periacrosomal region, the arms being nuclear only, in contrast with invasion of their chromatin with cytoplasm and microtubules in majids; and loss of a posterior median process, containing chromatin, which is present in majids as in raninids and homolids. The relationship ofCalocarcinuswith xanthids is unequivocally supported by (1) presence of a posterior circumperforatorial zone, the xanthid ring; (2) the precise form of the acrosome ray zone which is wide anteriorly and sends a long slender extension posteriorly to meet the ring; (3) the irregular external margin of the outer acrosome zone; (4) division of the operculum complex into a distinct upper zone and a lower, subopercular zone of lesser diameter; and (5) presence of an accessory ring around the operculum. Modification of the xanthid ring is typical of thoracotremes and partial modification inCalocarcinusmay indicate origin of thoracotremes from a related xanthoid stock. A difference ofCalocarcinussperm from those of xanthids is the (plesiomorphic) presence of centrioles, also seen in some heterotremes and thoracotremes. No synapomorphies which are not common to other heterotremes are shared betweenCalocarcinusand trapeziid sperm. Trapeziid sperm (plesiomorphically?) lack the xanthid ring, the posterior exteasion of the acrosome ray zone and the irregular margin of the outer acrosome zone ofCalocarcinusand xanthids. Apomorphic features of theCalocarcinus africanussperm include a spiral configuration of the contents of the outer acrosome zone (autapomorphy?), as seen in cross-section, and presence of a periopercular rim. A well developed periopercular rim is known elsewhere only inPotamonautes(family Potamidae), but a rudiment occurs in some xanthids (e.g.,Etisus). The periopercular rim is probably a true synapomorphy indicative of relationship of potamids to xanthoids (represented byCalocarcinus) which has been postulated elsewhere on morphological grounds.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672351

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The larval development ofPachygrapsus graciliswas studied in the laboratory under conditions of 25°C temperature and 20, 24, 28, 32 and 34% salinity. The objective of the study was to characterize the plankton phase of life of this species.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672352

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Juveniles ofLiocheles australasiaeborn in the laboratory were kept separate after leaving their mother's backs early in the second instar. They usually developed through five and sometimes six juvenile stages, becoming pregnant shortly after the final molt without having been impregnated by males. Therefore they must become pregnant parthenogenetically. Most of the juveniles became pregnant at about 15 months after birth, but a few required twice as long to mature and to become pregnant, resulting in two age classes at maturity.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672353

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The spermiogenesis of the brachiopodRhynchonella psittaceawas studied. The acrosome develops from cup-shaped acrosomal vesicles near the Golgi complex in the basal part of the spermatid. The acrosome vesicle then migrates to the apical region of the cell. The periacrosomal substance appears between the acrosomal vesicle and the nucleus. A ring-shaped mitochondrion is localized around the basal part of the nucleus. During spermiogenesis the proximal centriole is in contact with the nucleus via a single pericentriolar element. A distal centriole of the late spermatid has nine elements in a pericentriolar complex. The tail flagellum has a normal axonemal complex (9 + 2).

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672354

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The reproductive behavior of the honeydew moth,Cryptoblabes gnidiella(Millière) (Lepidoptera: Pyralidae), was studied in the laboratory. The sex ratio was 1.1:1, males to females, in both laboratory and field stocks. Most of the females that mated did so during the first night after emergence; males began mating on the following night. Mating occurred 1–2 h before dawn and averaged 100 min. Both sexes mated only once in one night. Most females mated only once in their lifetime, a few mated 2–4 times, whereas males mated up to six times per lifetime. Insects that lived longer also mated more times. When the sex ratio was altered from 3:1 to 1:3, males to females, the percentage of females that mated in one night dropped from 90 to 65, whereas the number of matings per male rose from 0.32 to 2.25. When fresh one-day-old females were provided daily at a ratio of three per male, the males averaged 1.4 matings per lifetime vs. 2.6 with 2- to 3-day-old females. A delay in mating did not affect the percentages of males and females that mated; highest percentages were obtained with 2- to 4-day-old males and females, but a delay in mating resulted in egg fertility dropping from 91 % to 73 %. The preoviposition period lasted a full day after mating, and then most of the eggs were laid during the first night. Average fecundity was 105 eggs per female (maximum: 230).

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672355

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The viviparous prosobranchLittorina saxatilishas a reduced capsule gland and lacks a jelly gland and, thus, eggs and embryos of this species are covered only by a thin envelope called the egg covering. This covering is three-layered and has a fibrillar structure. It was less thick when surrounding older embryos. After PAS-AB the covering stained very weakly; PAT-Ag Prot gave negative results. Lectin-cytochemistry showed that the inner and outer layer contain β-D-galactose; bromobimane-fluorescence revealed the occurrence of thiol groups and disulfide bonds. With different tracers it was demonstrated that the covering is permeable to water, lead and phosphate ions, amino acids (L-(35s) methionine), proteins (horseradish peroxidase, 40,000 Da) and probably also to substances with a higher molecular weight as indicated by some preliminary experiments with FITC-conjugated dextrans. SDS gel electrophoresis revealed several proteins in the albumen, which appear to be (at least partly) identical with those in the fluid of the brood pouch. Presumably the high permeability of the egg covering permits transfer of proteins from the brood pouch to the embryo. However, previous experiments suggested that possible feeding of the young by the mother seems not to be essential for normal development. Current evidence suggests, therefore, thatL. saxatilismay be regarded as lecithotroph viviparous.

ISSN:0792-4259    

DOI:10.1080/07924259.1993.9672356

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor