Characterization of biocontrol traits in the entomopathogenic nematode Heterorhabditis georgiana (Kesha strain), and phylogenetic analysis of the nematode’s symbiotic bacteria

Our objective was to estimate the biocontrol potential of the recently discovered entomopathogenic nematode species Heterorhabditis georgiana (Kesha strain). Additionally, we conducted a phylogenetic characterization of the nematode’s symbiotic bacterium. In laboratory experiments, we compared H. georgiana to other entomopathogenic nematodes for virulence, environmental tolerance (to heat, desiccation, and cold), and host seeking ability. Virulence assays targeted Acheta domesticus, Agrotis ipsilon, Diaprepes abbreviatus, Musca domestica, Plodia interpunctella, Solenopsis invicta, and Tenebrio molitor. Each assay included H. georgiana and five or six of the following species: Heterorhabditis floridensis, Heterorhabditis indica, Heterorhabditis mexicana, Steinernema carpocapsae, Steinernema feltiae, Steinernema rarum, and Steinernema riobrave. Environmental tolerance assays included Heterorhabditis bacteriophora, H. georgiana, H. indica, S. carpocapsae, S. feltiae, and S. riobrave (except cold tolerance did not include S. carpocapsae or S. riobrave). Host seeking ability was assessed in H. bacteriophora, H. georgiana, S. carpocapsae, and Steinernema glaseri, all of which showed positive orientation to the host with S. glaseri having greater movement toward the host than S. carpocapsae (and the heterorhabditids being intermediate). Temperature range data (tested at 10, 13, 17, 25, 30 and 35 °C) indicated that H. georgiana can infect Galleria mellonella between 13 and 35 °C (with higher infection at 17–30 °C), and could reproduce between 17 and 30 °C (with higher nematode yields at 25 °C). Compared with other nematode species, H. georgiana expressed low or intermediate capabilities in all virulence and environmental tolerance assays indicating a relatively low biocontrol potential. Some novel observations resulted from comparisons among other species tested. In virulence assays, H. indica caused the highest mortality in P. interpunctella followed by S. riobrave; S. carpocapsae caused the highest mortality in A. domesticus followed by H. indica; and S. riobrave was the most virulent nematode to S. invicta. In cold tolerance, S. feltiae exhibited superior ability to cause mortality in G. mellonella (100%) at 10 °C, yet H. bacteriophora and H. georgiana exhibited the ability to produce attenuated infections at 10 °C, i.e., the infections resumed and produced mortality at 25 °C. In contrast, H. indica did not show an ability to cause attenuated infections. Based on the phylogenetic analysis, the bacterium associated with H. georgiana was identified as Photorhabdus luminescens akhurstii.     

Increased incidence of pertussis and parapertussis in HIV-1-positive adolescents vaccinated previously with whole-cell pertussis vaccine

We investigated 296 adolescents (11–18 years), who had been immunized previously with the three doses of DPT vaccines. 48 were diagnosed positive for HIV-1. Nasopharyngeal swabs were obtained from 296 adolescents who presented with persistent cough and nasopharyngeal secretions. Nasopharyngeal swabs (calcium alginate) specimens were collected by passing the swabs through the nares into the posterior nasopharynx and rotating the swabs for a few seconds. The swabs were plated for culture of Bordetella organisms in charcoal cephalexin blood agar (CCBA). The CCBA plates were incubated for 2–6 days at 35 °C in a humid aerobic atmosphere. The suspected, shiny (mercury-like) colonies were tested by slide agglutination with antisera to B. pertussis and B. parapertussis, and urease, oxidase activities were performed. Results indicate that out of 48 HIV-1-positive adolescents, 18 had positive cultures for Bordetella organisms (14, Bordetella pertussis, and 4, Bordetella parapertussis). Of 248 HIV-1-negative subjects, 3 had Bordetella organisms (2, Bordetella pertussis, 1, Bordetella bronchiseptica). One of the subjects, a boy, aged 14 years, with Bordetella bronchiseptica had a dog as pet, which was found to be infected. The results indicate that adolescents with HIV-1 infection, despite being vaccinated against pertussis have a higher rate of infection when exposed to pertussis bacteria than HIV-1-negative adolescents. This revised version was published online in August 2006 with corrections to the Cover Date.     

Living with primary ciliary dyskinesia: a prospective qualitative study of knowledge sharing, symptom concealment, embarrassment, mistrust, and stigma

Background

Primary ciliary dyskinesia (PCD) is a chronic respiratory disease for which there is little psycho-social research and no qualitative studies of individuals living with the condition. A questionnaire-based survey in 2003 found evidence of stigmatisation in some individuals with PCD. Although the questionnaire had face and construct validity, stigmatisation was not cross-validated against interviews. The present study had the twin aims of carrying out a qualitative study of the adult patients living with PCD, and using a structured design to validate the questionnaire measure of stigma.

Methods

Interviews were carried out with six pairs of individuals with PCD, matched for sex, situs, and age, one with a high stigma score in 2003 and the other with a low stigma score. Depth-qualitative interviews were conducted by one author to explore themes surrounding the psycho-social impact of PCD using a grounded theory analysis. The interviewer was blind to the stigma scores of participants, and after the qualitative analysis was completed, the interviewer made an assessment of which member of each pair seemed the more stigmatised, after which the code was broken.

Results

Interviews revealed a number of themes, including other people's knowledge of PCD, the sharing of knowledge about PCD, the concealment of symptoms of PCD, embarrassment at symptoms, changes of behaviour in response to PCD, mistrust of medical care, in particular in relation to problems in diagnosis, a mistrust of general practitioners who were seen as poorly informed, and the importance of expert care at tertiary referral centres. Although stigmatisation as such was rarely mentioned directly by respondents, when the interviewer's judgement on level of stigmatisation was correlated with stigma scores from 2003, it was found that the more stigmatised member had been correctly identified in all six pairs (p = .016).

Conclusion

Our results suggest that some people with PCD feel isolated through mistrust in medicine, and lack of knowledge surrounding PCD. Many responses to PCD can be explained in terms of stigmatisation, and in particular felt stigma. The correlation between questionnaire used several years previously, and the interviewer's judgements of stigmatisation suggest that the stigma questionnaire had both predictive validity and long-term stability. As in other chronic conditions, stigmatisation occurs only in some individuals with PCD, and the present study explores the basis of stigmatisation, and validate the questionnaire as a measure of difference in stigma.     

Mortality of eggs of stored-product insects held under vacuum: effects of pressure, temperature, and exposure time

Low pressure applied to a commodity creates a low-oxygen atmosphere that can be effective to control stored-product insects. Previous work determined that eggs of several species of stored-product insects were among the most tolerant life stages to low pressure. The current study was conducted to determine the mortality of eggs in response to various pressures, temperatures, and exposure times. An initial experiment determined that the sensitivity of eggs to vacuum varied with their age. Eggs of Plodia interpunctella (Hübner) were most sensitive to low pressure when they were 3 or 48 h old, whereas those of Rhyzopertha dominica (F.) were most sensitive at 12 and 120 h of age. In subsequent experiments, eggs of Cadra cautella (Walker), P. interpunctella, R. dominica, and Tribolium castaneum (Herbst) were exposed to pressures of 50, 75, 100, 200, and 300 mmHg in glass chambers at 5, 15, 22.5, 30, and 37.5 degrees C for times ranging from 12 to 168 h. Time-mortality data were subjected to probit analyses and lethal dose ratios were computed to determine differences in lethal time values among species across the 25 low pressure-temperature combinations for each species. In all four species the mortality of eggs increased with increasing exposure time and temperature. Low temperatures and high pressures were the least effective conditions for killing eggs, compared with high temperatures combined with low pressures in all species investigated. These results provide important guidelines for developing treatment schedules for disinfestation of commodities on a commercial scale.     

Catecholamines inhibit Ca(2+)-dependent proteolysis in rat skeletal muscle through beta(2)-adrenoceptors and cAMP

Overall proteolysis and the activity of skeletal muscle proteolytic systems were investigated in rats 1, 2, or 4 days after adrenodemedullation. Adrenodemedullation reduced plasma epinephrine by 95% and norepinephrine by 35% but did not affect muscle norepinephrine content. In soleus and extensor digitorum longus (EDL) muscles, rates of overall proteolysis increased by 15-20% by 2 days after surgery but returned to normal levels after 4 days. The rise in rates of protein degradation was accompanied by an increased activity of Ca(2+)-dependent proteolysis in both muscles, with no significant change in the activity of lysosomal and ATP-dependent proteolytic systems. In vitro rates of Ca(2+)-dependent proteolysis in soleus and EDL from normal rats decreased by ~35% in the presence of either 10(-5) M clenbuterol, a beta(2)-adrenergic agonist, or epinephrine or norepinephrine. In the presence of dibutyryl cAMP, proteolysis was reduced by 62% in soleus and 34% in EDL. The data suggest that catecholamines secreted by the adrenal medulla exert an inhibitory control of Ca(2+)-dependent proteolysis in rat skeletal muscle, mediated by beta(2)-adrenoceptors, with the participation of a cAMP-dependent pathway.     

Marmoset phylogenetics, conservation perspectives, and evolution of the mtDNA control region

Marmosets (genus Callithrix) are a diverse group of platyrrhine primates with 13-15 purported taxa, many of them considered endangered. Morphological analyses constitute most of the basis for recognition of these forms as distinct taxa. The purpose of this study was to provide a molecular view, based on mitochondrial control region sequences, of the evolutionary history of the marmosets, concomitant with a molecular phylogenetic perspective on species diversity within the group. An additional purpose was to provide the first comparative examination of a complete New World monkey control region sequence with those of other mammals. The phylogenetic analyses provide convincing support for a split between the Atlantic forest and Amazonian marmosets, with the inclusion of the pygmy marmoset (Cebuella pygmaea) at the base of the Amazonian clade. The earliest branch of the Atlantic forest group was C. aurita. In the Amazonian group, the analyses do not support the recognition of C. humeralifer and the recently described C mauesi as distinct taxa. They do, however, support a clear distinction between C. argentata and a strongly supported mixed clade of C. humeralifer and C. mauesi. In the Atlantic forest group, the phylogenetic tree suggests mixing between C. penicillata, C. kuhli, and possibly C. jacchus. Most of the sequence features characteristic of other mammal control regions were also evident in marmosets, with the exception that conserved sequence blocks (CSBs) 2 and 3 were not clearly identifiable. Tandem repeat units often associated with heteroplasmy in a variety of other mammals were not evident in the marmoset sequences.      

Tolerance of pupae and pharate adults of Callosobruchus subinnotatus Pic (Coleoptera: Bruchidae) to modified atmospheres: a function of metabolic rate

Three developmental stages (pupae, early pharate and late pharate adults) of Callosobruchus subinnotatus (Pic.) were investigated for their tolerance or susceptibility to four modified atmospheres. Two of these atmospheres were hypercarbic and two were hypoxic. The hypercarbic atmospheres were found to cause mortality earlier than hypoxic atmospheres. Late pharate adults died earlier than pupae or early pharate adults. Late pharate adults that survived the exposure took a longer time to eclose than the pupae or early pharate adult.Using high resolution microrespirometric techniques, it was possible to record the oxygen consumption rate and CO(2) output of different developmental stages in air. The metabolic rate was determined manometrically as the oxygen uptake rate at an ambient temperature of 25 degrees C. The oxygen uptake rate differed significantly between groups of 20 individuals of different stages (p<0.01; t-test). The lowest rate of oxygen uptake (510.6+/-52.2 &mgr;l g(-1) h(-1)) was recorded in pupae. Higher oxygen uptake rates were found in early pharate adults (668.4+/-45.6 &mgr;l g(-1) h(-1)) and late pharate adults (1171.2+/-45.0 &mgr;l g(-1) h(-1)), and adult beetles (1310.4+/-53.4 &mgr;l g(-1) h(-1)). The patterns of CO(2) release were similar to those of oxygen uptake. CO(2) release was highest in eclosed adults and late pharate adults followed by early pharate adults, and lowest in pupae. The mode of CO(2) release ranged from continuous CO(2) release in pupae to discontinuous CO(2) release in late pharate and eclosed adults. Thus, high metabolic rates, and perhaps, in conjunction with discontinuous CO(2) of late pharate adults are responsible for their higher susceptibility to modified atmospheres than pupae and early pharate adults.     

Role of juvenile hormone-esterase in mating-stimulated egg development in the moth Heliothis virescens

Juvenile hormone (JH) titer in virgin females of Heliothis virescens is significantly lower than that in mated females of the same age. The JH titer in virgin females follows a diel pattern in which it begins to increase towards the end of photophase, remains high around the onset of scotophase, and declines during scotophase. The titer reaches its lowest levels at the onset of photophase, and remains low during the first half of photophase. In mated females, the diel pattern of JH titers is not as pronounced. JH-esterase (JHE) activity in mated females is significantly lower than that of virgin females during photophase; JHE levels in the former are similar to levels seen in newly emerged females. JHE activity in mated females also exhibits a diel pattern, in which activity is low during photophase and high at the onset of scotophase. Evidence for the indirect involvement of JHE in the mating-stimulated egg development is provided by the effect of selected JHE inhibitors in inhibiting JHE activity and stimulating egg production in virgin females.     

Functional response of <Emphasis Type="Italic">Pteromalus cerealellae</Emphasis> (Hymenoptera: Pteromalidae) on the cowpea weevil, <Emphasis Type="Italic">Callosbruchus maculatus</Emphasis> (Coleoptera: Bruchidae), and interaction between parasitism and cowpea varietal susceptibility

Laboratory studies were carried out to determine the functional response of the parasitoid, Pteromalus cerealellae (Boucek) to cowpea weevil, Callosobruchus maculatus (F.) hosts, and the relationship between parasitism and cowpea variety susceptibility to the weevil. The attack response of P. cerealella to weevil larvae was best described by a type III functional response using an egg limitation model. The mean attack rate (a) of the parasitoid was estimated as 1.7 and the upper limit of the response was 24 weevil larvae per individual parasitoid within a 48-h period. The results also showed that cowpea varieties resistant to weevil infestation supported fewer weevil progeny and facilitated a greater suppression of the weevil by the parasitoid. The parasitoid progeny index, a measure that compares the number of the parasitoid progeny to the number of the beetle progeny was higher in cowpea weevil resistant varieties than in susceptible varieties. Additionally, the presence of P. cerealellae resulted in reduced weight losses of cowpea caused by the weevil infestation in both susceptible and resistant varieties.