Life history characteristics of Wyeomyia smithii from New Jersey

We colonized Wyeomyia smithii (Coquillett) from southern New Jersey and studied life history characteristics in the laboratory. Males and females showed no significant difference in time spent from first to third instar, but female larvae remained in fourth instar 2.1 days longer than males. At 22 +/- 2 degrees C females emerged 22.6 +/- 3 days after egg hatch; males emerged approximately two days earlier. Male emergence peaked five hours after dawn; females showed a trend to emerge late in the day. Rotation of male terminalia was completed 9 to 11 hours after emergence. Females were capable of mating immediately after emergence. Wyeomyia smithii females laid their first egg batch four to six days after emergence. Females were capable of laying up to seven batches of eggs, however the mean number of eggs per oviposition decreased significantly as the number of oviposition cycles increased.

Familial cerebellar hypoplasia and pancytopenia without chromosomal breakages

Two siblings manifested a neuro-haematologic syndrome characterised by low birth weight, failure to thrive, chronic persistent tongue ulceration, severe truncal ataxia and pancytopenia without either telangiectasia or chromosomal instability. One sibling died from sepsis and the cerebellum demonstrated reduced cellularity of the molecular and granular layers with relative preservation of Purkinje cells and minimal gliosis. A surviving sibling has shown haematologic progression to a myelodysplastic disorder. There was no evidence of any chromosomal instability following exposure of fibroblasts and lymphocytes to irradiation. Monosomy-7 was not present in the surviving sibling. We suspect that these two patients represent another example of the rare Hoyeraal-Hreidarsson syndrome and we are currently engaged in very close monitoring of the surviving sibling for evidence of any karyotypic abnormality.

Ovarian development and parity determination in Culiseta melanura (Diptera: Culicidae)

A laboratory colony of Culiseta melanura (Coquillett) was used to follow ovarian development from emergence to oviposition and to validate the accuracy of using follicular dilatations to age grade females. We observed no change in the size of the primary follicles in unfed females from emergence to 3 d of age. Sugar feeding stimulated follicular growth and produced the following 3 types of ovarioles: (1) large primary follicles that eventually developed into functional ovarioles; (2) lesser numbers of small primary follicles that developed small amounts of yolk after blood feeding but degenerated in the latter stages of development; and (3) small primary follicles that did not develop yolk after blood feeding, exhibited accelerated growth, and became rogue ovarioles with multiple false dilatations. The yolk of the small primary follicles that degenerated after blood feeding was resorbed during stage IV of egg development, and the degenerating follicles resembled gonotrophic dilatations in the latter stages of the cycle. This process produced gravid females with some secondary follicles that appeared to possess a gonotrophic dilatation. Other authors have termed these artifacts false or agonotrophic dilatations. Degenerating ovarioles bearing these artifacts were used to determine physiological age in blood fed and gravid Cs. melanura. Nulliparous females in the latter stages of gonotrophic development have single false dilatations on degenerating ovarioles, 1-parous females have 2 false dilatations on degenerating ovarioles. In unfed, nulliparous females, false dilatations can be distinguished from true dilatations because they are attached to secondary follicles that are much smaller than the primary functional follicles that fill most of the ovary. In blood fed and gravid females, follicles that support false dilatations always lack yolk. Rogue ovarioles are unreliable indicators of physiological age and should not be used for diagnostic purposes.

Effect of temperature on the development of Culiseta melanura (Diptera: Culicidae) and its impact on the amplification of eastern equine encephalomyelitis virus in birds

Eastern equine encephalomyelitis virus (EEE) is perpetuated in a maintenance cycle that involves Culiseta melanura (Coquillett) as the enzootic vector and passerine birds as the amplifying hosts. Amplification of virus in any given year requires an influx of nulliparous Cs. melanura in the presence of susceptible avian hosts. We conducted laboratory experiments at constant temperatures from 10 to 34 degrees C to develop thermal heat summation models to predict emergence in nature. Embryonic development progresses slowly at 10 degrees C, and the time to eclosion decreased significantly as temperatures increased to 28 degrees C. High temperature were lethal and eggs failed to hatch at 32 degrees C. The thermal minimum (t0) for embryonic development was 9.38 degrees C, and 38.46 degrees-days (DD) were required for egg hatch. The time for larval development decreased with increasing temperatures. Cs. melanura larvae develop in subterranean habitats (crypts) where water temperatures remain below 20 degrees C throughout the summer. Under controlled conditions, egg hatch to emergence took 8 mo at 10 degrees C, 3 mo at 16 degrees C, and 1 mo at 22 degrees C. The thermal minimum for larval development (t0) was 8.5 degrees C, and 467.29 DD were required from eclosion to adult emergence. Our findings indicate that Cs. melanura is well suited to develop in cold water crypts where the larvae are collected most frequently. The mosquito appears to be bivoltine in the northeast with an overwintering generation of larvae that emerges as a spring brood of adults and a summer generation of larvae that emerges in fall. Higher than normal water temperatures hasten development of the summer generation and increase the probability for amplification of EEE by bringing large numbers of nulliparous mosquitoes into contact with recrudescing virus for subsequent transfer to the growing population of susceptible juveniles. Water temperatures in the crypts also may regulate the northern limit for virus amplification each year.

Laboratory bioassay to compare susceptibilities of Aedes aegypti and Anopheles albimanus to Bacillus thuringiensis var. israelensis as affected by their feeding rates

This study presents the effect of differences in the feeding rates of Aedes aegypti and Anopheles albimanus on their susceptibilities to Bacillus thuringiensis israelensis. Aedes aegypti was more susceptible than An. albimanus because of its faster rate of feeding. Aedes aegypti ingested 11.5 times more spores than did An. albimanus, resulting in lower LT50 values. Anopheles albimanus larvae fed at a slower rate and required fewer spores than Ae. aegypti to induce 50% mortality. These findings support earlier reports of much higher concentrations of B. thuringiensis required to kill various anopheline species.

Life-table attributes of Anopheles albimanus (Wiedemann) under controlled laboratory conditions

The life-table attributes of a laboratory-colonized strain of Anopheles albimanus Wiedemann from El Salvador were investigated under controlled environmental conditions (26 +/- 2 degrees C, 60 +/- 2% RH, and 16:8 L:D photoperiod). Larvae pupated seven days after eclosion and the adults emerged on day eight. Adult emergence success was 91% and sex ratio was not significantly different from 1:1. Females took a blood meal one day after emergence and laid eggs two days later. The mean time of reproduction was 10.8 days and the expectation of life at emergence was 18.8 and 14.1 days for females and males, respectively. The daily survivorship of females at emergence was 0.97, and their net reproductive rate, age at mean cohort reproduction, instantaneous rate of increase, and mean generation time was 309.2, 10.8 days, 0.319, and 18 days, respectively. The life expectancy of females 10 days after emergence was 13.4 days, and they were capable of taking four to six additional blood meals.

Observations on multiple bloodfeeding in field-collected Culiseta melanura

This study examined field populations of Culiseta melanura for evidence of partial blood meals and multiple feeding behavior. Engorged specimens that had 1/3 or less abdominal distention together with eggs in stage I-II of ovarian development were recorded as mosquitoes that had taken partial blood meals. Multiple blood meals were credited to engorged specimens with fresh blood as well as partially digested blood surrounded with separate peritrophic membranes and eggs in stage III or IV of ovarian development. Results indicated that only 17 of 532 Cs. melanura were captured with a partial meal, indicating that natural populations feed to repletion more than 95% of the time. Less than 1% of the specimens showed physical evidence of feeding on multiple hosts. Culiseta melanura appears to be highly efficient at obtaining a full blood meal and seems to be extremely reluctant to refeed once ovarian development has been initiated. As a result, multiple feeding does not appear to be important in the amplification of virus by this species.

Larval competition in Aedes triseriatus (Diptera: Culicidae): effects of density on size, growth, sex ratio, and survival

We assessed the effect of increased larval density on selected life table attributes of larval Aedes triseriatus. Larvae were reared at densities of 0.125, 0.250, and 0.375 larvae/cm3 of water. The parameters we evaluated included duration of each developmental instar, percent survival to adult emergence, sex ratio, and size of early and late emerging adults. The amount of time spent in the first and second instar was not affected by density, but crowding lengthened duration of later instars significantly. Males emerged earlier than females at all densities, and there was no difference in the ratio of males to females due to crowding. Crowding did increase the overall developmental time of both sexes and produced significantly smaller adults of both sexes. Densities of 0.375 larvae/cm3 resulted in a significant increase in mortality. Results suggest that the effects of crowding in container habitats should be allowed for in the construction of time-specific life tables where duration of larval instars is used in the calculations. The importance of smaller body size as a result of crowding in container habitats is discussed in terms of vector competence of Ae. triseriatus in the transmission of LaCrosse encephalitis virus.

A thermal heat summation model to predict the duration of the gonotrophic cycle of Culiseta melanura in nature

This study determined the effect of temperature on the gonotrophic cycle of Culiseta melanura and developed a thermal heat summation model to calculate its duration under field conditions. A colony of Cs. melanura was used from New Jersey (F13-F17 generation) and the length of the gonotrophic cycle was observed at 2, 10, 16, 22, 28, 32 and 34 degrees C. None of the mosquitos survived at 2 degrees C or 34 degrees C and none laid fertile eggs at 32 degrees C. A linear regression analysis on the data showed that the thermal minimum for ovarian development was 6.4 degrees C and 95.87 degree days were required above 6.4 degrees C to complete one gonotrophic cycle. A thermal heat summation model is presented to allow calculation of the duration of the gonotrophic cycle under field conditions when average temperatures are known.

Age-related changes in development of the accessory glands of male Anopheles albimanus

This study presents the effects of age on the accessory glands of male Anopheles albimanus. The paired oval glands have an outer muscular layer and an inner layer of columnar secretory cells. Male pupae have uniformly long columnar cells and contain only traces of male accessory gland substance (MAGS). In newly emerged males, the posterior section of the gland has short columnar cells that produce an opaque, white MAGS consisting of one type of secretory granules. The anterior section has long columnar cells that produce yellow as well as white MAGS. In 84-h-old males, the columnar cells are short throughout the gland and the glands are replete with both forms of MAGS. The amount of MAGS may control secretory activity of the columnar cells by a feedback mechanism.

Feeding the mosquito Aedes aegypti with TMOF and its analogs; effect on trypsin biosynthesis and egg development

Female Aedes aegypti that were given a blood meal by enema deposited yolk in their oocytes and synthesized trypsinlike enzymes in their midgut. When females were given an enema of Aea-TMOF (Trypsin Modulating Oostatic Factor) (NH2-YDPAPPPPPP-COOH) and blood both egg development and trypsin biosynthesis were inhibited. Similar results were observed if TMOF was mixed with the blood meal and fed to female mosquitoes through a membrane. Renin inhibitor (NH2-PHPFHFFVYK-COOH) or poly proline given by enema with the blood meal did not affect egg development or trypsin biosynthesis. Feeding of TMOF analogs P1 (NH2-YDPAP-COOH) or P4 (NH2-YDPAPPPP-COOH) inhibited trypsin biosynthesis in the midgut. Injecting or giving an enema of an amidated peptide (NH2-WRPGPPPPPP-CONH2) of HIV-2 X-ORF protein also inhibited egg development and trypsin biosynthesis in the mosquito gut. When [3H]TMOF was purified by high performance liquid chromatography (HPLC) and fed with the blood meal through a membrane to female mosquitoes, [3H]TMOF outside the gut increased linearly for the first 24 h and 28% of the hormone was found outside the gut at 72 h. These results suggest that TMOF and its active analogs traverse the gut epithelial cells into the hemolymph, bind TMOF gut receptor(s) and modulate trypsin biosynthesis.

Anopheles culicifacies: effects of age on the male reproductive system and mating ability of virgin adult mosquitoes

Under controlled laboratory conditions of 28-30 degrees C and 16:8 L:D photoperiod, an attempt was made to develop an age-grading technique for Anopheles culicifacies males. Mating activity was maximal when females were 5-12 days old males were 5-7 days old. The numbers of total and mature spermatocysts declined significantly with age, and the proportion of the testes occupied by the sperm reservoir increased as virgin males grew older. Mating resulted in the loss of spermatozoa and accessory gland substance from the reproductive system. Loss of mating ability of older virgin males seemed to be age-related, because the reproductive system contained ample supplies of accessory gland substance and spermatozoa. Morphological changes of the reproductive system, due to mating and age, were used to infer the age and reproductive history of unknown males in a laboratory evaluation.

Dual inhibition of platelet-activating factor and arachidonic acid metabolism by ajmaline and effect on carrageenan-induced rat paw oedema

The effects of ajmaline on human platelet aggregation, arachidonate metabolism and platelet activating factor (PAF)-induced lethality in rabbits were examined. Platelet aggregation induced by several stimuli (ADP, collagen, and PAF) was inhibited by increasing concentrations of ajmaline. The potency of ajmaline was higher when PAF was employed as stimulating agent in comparison with other agonists (IC50 70, 270 and 380 microM for PAF, ADP and collagen, respectively) whereas ajmaline had no effect against arachidonic acid-induced aggregation. In contrast however, ajmaline inhibited arachidonate metabolism by platelet homogenates. The formation of both thromboxane A2 and 12-hydroxy-eicosatetraenoic acid was inhibited by ajmaline with comparable potencies. Pretreatment of rabbits with ajmaline (50 mg kg-1) completely abolished the lethal effects of PAF (11 micrograms kg-1) given intravenously (P < 0.001). In addition, ajmaline at doses ranging from 50 to 100 mg kg-1 inhibited carrageenan-induced rat paw oedema (P < 0.001). In this test ajmaline was three times more potent than aspirin. In the light of these results we conclude that ajmaline, a known anti-arrhythmic agent is a PAF antagonist and a dual inhibitor of platelet cyclo-oxygenase and lipoxygenase enzymes with anti-inflammatory properties.

Biosynthesis of serine proteases in Lutzomyia anthophora (Diptera: Psychodidae)

Changes in the biosynthesis of serine proteases in adult Lutzomyia anthophora Addis were followed and compared with the larval and pupal stages. More chymotrypsinlike than trypsinlike enzyme was synthesized by 2-d-old and 3-d-old sugar-fed females and females that were fed blood 72 h earlier. A small increase in the amount of chymotrypsinlike enzyme occurred within the first 48 h after blood feeding, whereas trypsinlike enzyme activity increased rapidly after the blood meal and peaked at 72 h. [1,3-3H]DIP trypsinlike and chymotrypsinlike derivatives of sugar-fed and blood-fed females were compared using polyacrylamide gel electrophoresis.

Inhibition of platelet activating factor by ajmaline in platelets: in vitro and in vivo studies

The in vitro and in vivo effects of ajmaline and its derivatives on platelet aggregation and platelet-activating factor (PAF) induced death in rabbits was studied. Ajmalinc and acetyl ajmaline selectively inhibited PAF-induced aggregation in a concentration related manner. Weak or no inhibition of aggregation was observed when ADP, collagen or arachidonic acid were used as aggregating agents. Similarly ajmaline or acetyl ajmaline also inhibited the lethal effects of PAF in the rabbit. PAF (8-11 microg/kg i.v.) caused sudden death in rabbits due to platelet aggregation and cardiac failure. Pretreatment of rabbits with ajmaline (50 mg/kg i.p.) protected conscious rabbits from PAF (11 microg/kg i.v.)-induced death. Since PAF is a powerful inducer of platelet aggregation via stimulation of specific PAF membrane receptors, our data is suggestive that ajmaline (an anti-arrhythmic agent) could emerge as a new class of PAF antagonists.

The Muir-Torre syndrome: a disease of sebaceous and colonic neoplasms

The Muir-Torre syndrome of sebaceous neoplasms of the skin, with or without keratoacanthomas, and multiple low-grade visceral malignancies with prolonged survival is a rare disorder. Colonic polyps are frequently present, and the syndrome appears to be familial. We report 2 unrelated patients with the Muir-Torre syndrome. Each case exhibited sebaceous adenomas. Gastrointestinal findings included colonic adenocarcinomas and a tubulovillous adenoma. Although an unusual disease, the Muir-Torre syndrome requires recognition because these patients are at risk for multiple primary malignancies and may have family members also at risk.

Absence of teratogenic effects of progesterone on the developing genital tract of the human female fetus

It has been questioned whether prenatal exposure to progesterone, like exposure to diethylstilbestrol (DES), results in teratogenic abnormalities of the upper and lower genital tract in human females. Through the use of a recently described model in which human fetal reproductive tracts can be transplanted and grown in vivo for extended periods in athymic nude mice, genital tracts from human female fetuses, ages 7 to 18 weeks postovulation, were grafted into castrated murine hosts and grown for 4 to 10 weeks in the presence or absence of continuous exposure to progesterone. Substantial growth was observed. For all specimens, the morphogenetic process proceeded normally, resulting in the harmonious organization of a complete, well differentiated genital tract composed of fallopian tubes, uterine corpus, and cervix and vagina. The fallopian tubes were highly convoluted and disclosed fimbria. The uterine corpus was lined by a simple columnar epithelium; two layers of stroma in the wall were distinctly separated from each other. In the older specimens, the outer layer of stroma had assumed microscopic properties diagnostic of smooth muscle (myometrium). In the majority of specimens the region of the cervix/vagina disclosed the development of a fornix-like evagination at which point or slightly cranially there was a gradual but defined transition from columnar epithelium to squamous epithelium. The inner layer of endometrial stroma tapered and disappeared at or close to the squamocolumnar junction. The vaginal stroma was a single homogeneous layer and was continuous with the myometrium of the uterine corpus. In the context of this model system, prenatal exposure of the developing human female genital tract of progesterone was not associated with any obvious teratogenic effects.