Biomedical subjects
Publications and source records attributed to J H Bryan.
Specimens identified morphologically as Anopheles punctulatus revealed 2 genetically distinct entities in samples collected in the Western Province of Papua New Guinea. We regard one of these species as conspecific with An. punctulatus and the other as a new species designated here as An. sp. near punctulatus.
Entomological studies were undertaken in three villages in the East Sepik Province of Papua New Guinea. The inhabitants of one village, Nanaha, had been treated with diethylcarbamazine (DEC) to reduce the prevalence and density of microfilaraemia of Wuchereria bancrofti. No intervention was undertaken in the other two villages, Yauatong and Musenau, in which bancroftian filariasis was present but with markedly different human prevalence rates and mean parasite densities. In Yauatong, infection rates in anopheline vectors (Anopheles punctulatus and An. koliensis) varied from 20.5 to 46.6% with infectivity rates of 0-1.4% while these rates were 10.9-14.3% and 0-1.1% respectively in Culex quinquefasciatus. In Nanaha after DEC treatment, infection rates were as high as 16.3% in An. koliensis and infectivity rates reached 7.0% for An. punctulatus despite a 45% reduction in the number of people with detectable microfilariae (mf) and a 94% reduction in mf density in those who remained positive.
Four species within the Anopheles punctulatus group of mosquitoes (Diptera: Culicidae) were identified by allozyme analysis of samples collected from thirty-three localities in Guadalcanal, Makira, Malaita, Temotu and Western Provinces in the Solomon Islands and six localities on Efate, Espiritu Santo, Maewo and Malekula Islands in Vanuatu. Three of these species are members of the An.farauti complex. A key is given to identify five species of the An.punctulatus group known to occur in the Solomon Islands using their isoenzyme characteristics. An.farauti No. 1 was widespread in coastal areas of the Solomon Islands and was the only species detected in Vanuatu, including Efate Island (where Faureville is the type locality of An.farauti Laveran sensu stricto). An.farauti No. 2 and An.punctulatus were common in the Solomon Islands in more inland areas. An.farauti No. 7, reported here for the first time, was found as larvae in freshwater at six localities on north Guadalcanal. Three other members of the An.punctulatus group which have been reported previously from the Solomon Islands: An.koliensis, An.renellensis and an electrophoretic variant of An.farauti sensu lato, were not found in our samples. Previously recognized vectors of malaria and bancroftian filariasis in the Solomon Islands are An.farauti No. 1 (i.e. An.farauti s.s.), An.koliensis and An.punctulatus s.s. Adult females of An.farauti No. 2 and An.farauti No. 7 were not attracted to human bait in areas where their larvae occurred, indicating that these two species are not anthropophilic and therefore unlikely to transmit human pathogens.
Genomic DNA probes were made for five members of the Anopheles punctulatus complex of mosquitoes found in Papua New Guinea. Specific DNA probes were developed for An. punctulatus, An. koliensis, and three sibling species, An. farauti No. 4, An. farauti No. 5, and An. farauti No. 6, by differentially screening total genomic DNA libraries of individual species and sibling species with homologous DNA against heterologous DNA labeled with 32P. Probes ranged from 273 to 630 bp. Identification of species can be made from squash or dot blots using only a segment of the mosquito (i.e, head, thorax, abdomen, or even legs), allowing for concurrent analysis of the remainder of the mosquito for other epidemiologic characteristics.
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Among samples collected from nineteen localities in Papua New Guinea, we have identified six species within the Anopheles punctulatus complex of mosquitoes, by means of cellulose acetate allozyme electrophoresis. An.punctulatus Dönitz sensu stricto was collected from seven villages in the Madang area and from Buksak, Sausi Mission and an area 18 km SW of Tari; An.koliensis Owen from eight villages in the Madang area, from Popondetta and Brown River near Karema; and An.farauti No. 1 from ten coastal areas including Madang, Lorengau, Popondetta, Port Moresby, Rabaul and Wewak. Three newly recognized species, reported here for the first time, are designated as An.farauti No. 4 from Gonoa and Hudini, Madang area; An.farauti No. 5 from Ketarabo near Goroka; and An.farauti No. 6 from Hiwanda near Tari. Three other known members of the complex, An.clowi Rozeboom & Knight, An.farauti No. 2 (Bryan, 1973) and An.farauti No. 3 (Mahon & Meithke, 1982) were not detected in Papua New Guinea. Problems arising with morphological characters for the identification of species in this group are discussed.
Electrophoretic keys are given for the six species of the Anopheles punctulatus complex (Diptera: Culicidae) known from Papua New Guinea plus An.farauti No. 2 and No. 3 from Australia. The categories 'faster', 'standard' and 'slower' are used in keys to relate allozyme band migration following cellulose acetate electrophoresis to the standard pattern. Alternative keys are given depending on the availability of different species for use as standards.
The dispersal of Culex annulirostris, a major arbovirus vector in Australia, was studied in Griffith, N.S.W. using a mark-release-recapture technique. From an empirical model of dispersal, fitted to data on recaptured adults, the average distance dispersed was 6.8 km (95% c.l. 4.1-40.9 km), and 50% of the population dispersed 4.8 km or more. Maximum recorded dispersal was 8.7 km, and 2 individuals traveled more than 5 km in 1 day. The relevance of the findings to control strategy is discussed.
The dispersal of Culex annulirostris was studied during February 1986 in Griffith, N.S.W. using a mark-release-recapture technique. Parity was determined of recaptured females and a sample of the population at release. Parity rates of the 2 populations were comparable, and no significant differences were detected between the dispersal characteristics of the nulliparous and parous recaptured females. The maximum flight distance observed was 12 km, the limit of the trapping network. It was estimated that the mean distance traveled was 4.4 km and 36.6% (n = 377) of the population dispersed further than 5 km. The majority (81.2%, n = 377) of recaptures were taken within 2 days of release and the rate of dispersal of the population was estimated at 2.2 km/day.
Animals homozygous for the recessive, pleiotropic, mutation hpy(hydrocephalic-polydactyl) develop hydrocephalus early in the postnatal period. The condition develops in the apparent absence of any overt indications of obstruction in the cerebrospinal fluid (CSF) drainage system suggesting a continued, inappropriate, secretion of CSF. Electron microscope investigations were undertaken to both characterize and quantify the cell types present in the choroidal epithelium of mutants and their wild-type littermates and to gauge their response to a prolonged (24 h) deprivation of water, which has severe adverse effects on the general body fluid balance. Collectively, the findings indicate that the cellular makeup of the choroidal epithelium of normal animals and the manner of its response to changing fluid conditions is more complex than formerly anticipated. Also that inferences derived from a simple extrapolation of findings from other fluid-transporting epithelia to choroidal cells are misleading and erroneous. In wild-type animals allowed free access to water light cells with clavate microvilli (secretory cells) predominated whereas, following water deprivation there was a preponderance of dark cells with filiform microvilli, abundant mitochondria, multivesicular bodies and osmiophilic droplets (resorptive cells). In hydrocephalic mutants, the makeup of the choroidal epithelium of non-water-deprived animals resembled that of water-deprived wild-type mice and showed little change following water deprivation. These findings suggest that while the choroidal cells of mutants are capable of mounting a response to conditions having adverse effects on water balance (i.e., hydrocephalus) their response falls short of the level needed to fully redress the imbalance and is not materially increased by imposition of further, stringent, conditions (e.g., water deprivation). Thus, the findings lend support to the view that the mutational event affects the regulation of solute transport rather than effecting abrogation of the membrane pump itself.
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Ingestion of Wuchereria bancrofti microfilariae (mf) from humans by 639 Anopheles gambiae, 557 An. arabiensis, 117 An. melas and 9 An. funestus was investigated. The mf densities in blood fell into 3 groups; 0-32mf/ml, 107-122 mf/ml and 421-1140 mf/ml. In An. gambiae and An. arabiensis percentage of mosquitoes ingesting mf was strongly associated with mf density in host blood; in An. melas the association was much weaker. Mean number of mf ingested per mosquito was also strongly correlated to mf density in An. gambiae and An. arabiensis but not in An. melas. At low mf densities both An. gambiae and An. arabiensis concentrated mf, with concentration decreasing as density increased. From regression analysis, observed and expected uptake of mf would be equal at 622.9 mf/ml in An. gambiae and 391.6 mf/ml in An. arabiensis.
Microfilariae (mf) of Wuchereria bancrofti from the midgut of 639 Anopheles gambiae, 557 An. arabiensis, 117 An. melas and 9 An. funestus were examined immediately after the mosquitoes had fed on carriers with different densities of mf. The percentages of mf damaged during ingestion were 57.1-60.0 in An. gambiae, 33.3-50.6 in An. arabiensis and 38.7-55.7 in An. melas. In each species the percentage of mf damaged was independent of mf density in the human host. A further 3657 An. gambiae, 2875 An. arabiensis, 347 An. melas and 32 An. funestus were examined 7 d or more after feeding on mf carriers. In An. gambiae and An. arabiensis, mean numbers of larvae per mosquito were strongly correlated to mf blood density, with similar regression slopes to those obtained from the regression of mf blood density on mean uptake of mf/mosquito. The ratio of mean numbers of larvae per mosquito to mean numbers of intact mf ingested per mosquito increased as the density of mf in the human host increased in An. gambiae and An. arabiensis, but decreased in An. melas as host mf density increased.
A capture-recapture experiment with the filariasis vector Anopheles punctulatus from Papua New Guinea (PNG) is described. Eight hundred and ninety-seven engorged females collected indoor resting or in landing catches were released, and 82 were subsequently recaptured. Infection rates were higher in recaptured mosquitoes than in unmarked ones. Recapture rates declined exponentially with distance from the release site, but an infected female was recaptured 1.8 km from the release site. The estimated oviposition interval of 2.90 days was shorter than that obtained from the same species elsewhere in PNG, but daily survival rates were similar. Infection with Wuchereria bancrofti did not appear to affect the survival of the mosquito. Collections adequately sampled the resting population from inside a room of an experimental house.
The vectors of Wuchereria bancrofti were investigated in two areas of the Sepik Provinces of Papua New Guinea. At the village of Yauatong, indoor-resting Anopheles punctulatus had an infection rate of 47.3% and an infective rate of 3.4%. No infections occurred in 382 Culex annulirostris obtained in night-landing catches. At the village of Yankok only An. koliensis contained infective larvae but An. punctulatus and Cx quinquefasciatus were infected. Probit values of the cumulative percentages of filariae-positive mosquitoes plotted against the logarithm of the corresponding filaria count are illustrated.
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Changes in nuclei and nucleoli of cells of chicken cecum infected with Eimeria tenella were studied in living cells by interference microscopy and in fixed and stained tissues using light level microscopy. As soon as merozoites began to transform into second generation meronts, there was an increase in the size of both the nucleus and the nucleolus of the host cell. The dry weight of the nucleus increased somewhat, but there was a greater increase and a correlation of the dry mass of the nucleolus with the size of the parasite as measured by interference microscopy. In fixed and stained tissues, there was a correlation between the area of the nucleolus and the area of the parasite. Removal of nucleic acids with DNase and/or RNase showed high concentrations of both in the nucleoli and a residue of protein. The increased nucleolar size indicates a high level of transcription in infected cells and allows the conclusion that the parasite somehow induces transcription to occur. Since transcription is a highly specific process, the high degree of host and site specificity shown by nearly all coccidia is consistent with a hypothesis that the coccidia share a portion of the host genome.
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