The effect of osmotic stress on behaviour and water content of infective larvae of Trichostrongylus colubriformis

The role of the cuticle and sheath in the water dynamics of the infective larvae of Trichostrongylus colubriformis under osmotic stress and the effect of osmotic stress on behaviour have been investigated. In hypotonic solutions larvae lose the activity response to mechanical stimulation and there was also some increase in coiling. Larvae can regulate their water content in hypotonic solutions but lose water slowly in hypertonic solutions. Removal of the sheath by exposure to sodium hypochloritc or to a ‘natural’ stimulus had little effect on the water dynamics of infective larvae. The sheath thus appears to be freely permeable to water when hydrated whereas the cuticle has a very restricted permeability.     

Cell division during the development ofArtemia salina

Summary Cell division during embryonic development of the brine shrimp,Artemia salina has been studied by counting nuclei and mitotic figures. No cell division was observed during development of the encysted gastrula until about an hour before emergence of the embryo (a pre-nauplius) from the cyst, and even then only a few mitotic figures were observed. Following emergence, and during further development up to the stage II nauplius larva an increase of about 25% in the number of cells occurs. However, when the newly hatched larva is exposed to FUdR (10 g/ml) cell division is largely inhibited, but observable development nevertheless proceeds normally. Evidently all processes involved with the development of the gastrula into a stage II nauplius larva can occur with far fewer cells than normally are present.     

Larval adhesive organs and metamorphosis in ascidians

Summary The larva of Distaplia occidentalis bears three cup-shaped adhesive papillae, each with a prominent axial protrusion. At the onset of metamorphosis these organs rapidly evert through fenestrations in the cuticular layers of tunic exposing hyaline caps of adhesive. Additional adhesive material is secreted from collocytes during eversion. The stickiness of the papillae facilitates attachment to a variety of substrates.Each papilla is composed of more than 900 cells; six different types were identified. The wall of the cup contains about 260 myoepithelial cells with long attenuated processes. These extend from the rim of the cup to the base in the parietal (inner) layer. The apices of the myoepithelial cells are held in place by 11 pairs of specialized anchor cells bearing long bulbous microvilli. When the myoepithelial cells contract they force the axial protrusion forward and transform the papilla into a hyperboloidal configuration. The papilla is innervated by small motor fibers, but sensory fibers were not detected. The adhesive papillae of Distaplia are discussed in relationship to nine other recognizable types of papillae in the ascidians.     

A case of Strongyloides stercoralis infection.

Strongyloidiasis has been recognized as one of the life-threatening parasitic infections in the immunocompromised patients. We report an intestinal infection case of Strongyloides stercoralis in a 61-year-old man. Rhabditiform larvae were detected in the stool examination and developed to filariform larvae having a notched tail through the Harada-Mori filter paper culture. The patient received five courses of albendazole therapy but not cured of strongyloidiasis.     

韭菜迟眼蕈蚊幼虫消化系统的解剖学和组织学

本利用石蜡切片对韭菜迟眼蕈蚊幼虫其消化系统的组织学进行了研究。结果表明,幼虫的消化道无特殊变异,但中肠亚端部的一对胃盲囊长而发达,是消化道的突出特征。中肠和胃盲囊不同部位的细胞学特点有明显差异。根据中肠细胞形状及其分布将中肠分为4个区域,对中肠不同区域的细胞学特点进行了描述。     

Stages of embryonic development in the Atlantic cod Gadus morhua

The early development of the Atlantic cod, Gadus morhua was studied from fertilization until first-feeding. Multiple families were reared at 7 degrees C and a developmental staging series was prepared using morphological landmarks visible with the light microscope. Stages were named rather than numbered to allow for future additions and broadly grouped into larger time intervals called periods. The most useful staging features were found to be initially cell number, and later in development, somite number. The mean cell cycle time for the first six cleavages was 135 min and the linear regression equation for development of somites(s) over time (t) was s = 0.29t - 18.14. The segmentation period began at 220 h postfertilization (hpf), and unlike some other teleosts, the addition of new somites continued throughout the majority of embryonic development, until just prior to hatching. Hatching occurred at 256 hpf, after which individuals remained motionless at the water's surface, undergoing negative phototaxis only after the first day posthatch. The first-feeding stage was reached at the end of the third day posthatch, subsequent to development of a functional jaw and hindgut. This staging series provides an essential baseline reference for future experiments involving developing cod embryos and for the aquaculture industry.     

Reproduction of the Endangered Killifish Aphanius iberus at Different Salinities

Adult fish of a freshwater population of the Iberian endangered cyprinodontid Aphanius iberus, were induced to reproduce at salinities of 5, 15, 30, 45 and 60ppt. For each salinity five 30l aquaria were used, each one including a male and two females. Maturity and spawning outside the natural season, were obtained at conditions of 22 to 28°C and a photoperiod of 14L:10D. The larvae were fed with rotifers Brachionus plicatilis and Synchaeta cecilia valentina. Experiment lasted 40 days. The first spawning occurred on the 17th day at 45ppt of salinity and the first embryos hatched on the 34th day at 5 and 15ppt salinity. The final average number of larvae per aquarium ranged from 5.2 (45ppt salinity) to 10.8 (15ppt salinity). No significant differences were found between the average values at different salinities (p<0.01).     

Suspected intestinal myiasis due to Dryomyza formosa in a Japanese schizophrenic patient with symptoms of delusional parasitosis

A third-stage larva of Dryomyza formosa (Wiedemann) (Diptera: Dryomyzidae) was found in the fresh stool of a 27-year-old Japanese woman resident of Shiobara, 150 km north of Tokyo, on 16 November 1998. This is the first record of myiasis due to Dryomyza. Detection of this maggot (2cm long) by the patient herself was associated with her longstanding delusion of abdominal parasitosis as a symptom of chronic schizophrenia. Circumstantial evidence agreed with this being a genuine case of intestinal myiasis, apparently due to accidental ingestion of the insect, with no signs that the patient had contrived the report, nor that the maggot had invaded the stool post-defaecation. This case draws attention to the likelihood that some personality states are predisposed to noticing and reporting myiasis, when it occurs. We review other conditions (mental and physical) that are more prone to myiasis.     

The evolution of anural larvae in molgulid ascidians

Ascidians are urochordates, marine invertebrates with non-feeding motile chordate tadpole larvae, except in the family Molgulidae. Urodele, or tailed, Molgulids have typical ascidian chordate tadpole larvae possessing tails with muscle cells, a notochord, and a dorsal hollow nerve cord. In contrast, anural (or tail-less) Molgulids lack a tail and defining chordate features. Molecular phylogenies generated with 18S and 28S ribosomal sequences indicate that Molgulid species fall into at least four distinct clades, three of which have multiple anural members. This refined and expanded phylogeny allows careful examination of the factors that may have influenced the evolution of tail-less ascidians.     

External Features of the First Instar Larva of Damaster (Coptolabrus) jankowskii jankowskii (Coleoptera; Carabidae)

ABSTRACT Larval features of the carabid beetle, Damaster (Coptolabrus) jankowskii jankowskii (Oberthür) were investigated for the first time. For accomplishing the purpose, the adult beetles were collected by pitfall traps in the deciduous forest of Mt. Palgongsan, southern Korea. They have been reared under the laboratory condition of 16L: 8D at 20°C. The first instar larvae were obtained by isolating eggs after oviposition and were kept at the same condition. In the present study, external morphology of the first instar larva of this subspecies are described and its important character states and comparisons with the kin species are also discussed.