Orientation and ingestion rates of larval Anopheles albimanus in response to floating particles

Response of fourth-instar larvae of Anopheles albimanus Wiedemann (Diptera: Culicidae) to food and inert particles floating at the water surface was studied. In a choice test, larvae aggregated at powdered organic materials (blood meal, liver powder alfalfa flour and wheat flour) but not at inert materials (kaolin, chalk or charcoal). Larvae responded positively to proteins as well as some carbohydrates, but not to cellulose. Retention of larvae at food sources found by random locomotion was found to be responsible for larval aggregation. Larvae ingested food particles 6–9 times faster than insert particles. The significance of Anopheline feeding behavior in the development of formulations of stomach toxins (bacterial agents) used in larval control is discussed.

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Zusammenfassung Die vorliegende Studie befasst sich mit Verhaltensreaktionen von Anopheles albimanus Viertlarven auf an der Wasseroberfläche schwimmende Partikel. Verteilung und Orientierung der Larven wurde in einer Wahlapparatur quantifiziert. Nach Auftrag von Alfalfamehl, Weizenmehl, Stärke, Blutmehl, Leberpulver und Fischmehl wurde Aggregation der Larven in den beköderten Fächern der Apparatur beobachtet. Sowohl Proteine (Casein) als auch einige Kohlehydrate (Amylose, Amylopectin) lösten Aggregationen der Larven aus. Im Unterschied dazu führte Auftrag von Kreide, Kaolin, Polyaethylenpulver, Talcum oder Cellulose nicht zu Aggregationen. Zur Beschreibung der Entstehung larvaler Aggregationen bei Futterstoffen wurden die Schwimmbewegungen der Larven in Anwesenheit von Weizenmehl als Ködersubstanz quantifiziert. Da keine Attraktion der Larven im Sinne einer gerichteten Schwimmbewegung beobachtet werden konnte, wird geschlussfolgert, dass sofortige Beendung der Suchaktivität der Larven bei zufällig gefundenen Futterquellen für die beobachteten Aggregationen bei organischen Substanzen verantwortlich ist.Die Fressraten der Larven bei Angebot verschiedener Substanzen im Überschuss wurde bestimmt. Larven fülten drei von insgesamt sechs Darmabschnitten innerhalb von 15–30 min bei Angebot von Futtersubstanzen, während die Füllung von nur zwei Darmabschnitten mit inerten Materialien erst nach 90–120 min zu beobachten war. Die Resultate werden in Bezug auf wasseroberflächengebundene Formulierungen von Frassgiften diskutiert. Inerte Trägersubstanzen werden wahrscheinlich wesentlich langsamer aufgenommen als Futtersubstanzen. Da An. albimanus Larven nicht von Futterquellen angezogen werden, ist eine rasche und wirksame Giftaufnahme besonders dann zu erwarten, wenn die gesamte Oberfläche der Brutgewässer mit toxinhaltigen Trägerpartikeln bedeckt werden kann.

     

Cloning of rat brain succinyl-CoA:3-oxoacid CoA-transferase cDNA. Regulation of the mRNA in different rat tissues and during brain development.

3-Oxoacid CoA-transferase, which catalyses the first committed step in the oxidation of ketone bodies, is uniquely regulated in developing rat brain. Changes in 3-oxoacid CoA-transferase activity in rat brain during the postnatal period are due to changes in the relative rate of synthesis of the enzyme. To study the regulation of this enzyme, we identified, with a specific polyclonal rabbit anti-(rat 3-oxoacid CoA-transferase), two positive cDNA clones (approx. 800 bp) in a lambda gtll expression library, constructed from poly(A)+ RNA from brains of 12-day-old rats. One of these clones (lambda CoA3) was subcloned into M13mp18 and subjected to further characterization. Labelled single-stranded probes prepared by primer extension of the M13mp18 recombinant hybridized to a 3.6 kb mRNA. Rat brain mRNA enriched by polysome immunoadsorption for a single protein of size 60 kDa which corresponds to the precursor form of 3-oxoacid CoA-transferase was also found to be similarly enriched for the hybridizable 3.6 kb mRNA complementary to lambda CoA3. Affinity-selected antibody to the lambda CoA3 fusion protein inhibited 3-oxoacid CoA-transferase activity present in rat brain mitochondrial extracts. The 3.6 kb mRNA for 3-oxoacid CoA-transferase was present in relative abundance in rat kidney and heart, to a lesser extent in suckling brain and mammary gland and negligible in the liver. The specific mRNA was also found to be 3-fold more abundant in the brain from 12-day-old rats as compared with 18-day-old foetuses and adult rats, corresponding to the enzyme activity and relative rate of synthesis profile during development. These data suggest that 3-oxoacid CoA-transferase enzyme activity is regulated at a pretranslational level.     

Modifications in the surgical correction of trigonocephaly

A modified technique for the surgical correction of trigonocephaly is presented. The technical modifications are designed both to increase the stability of fixation of the supraorbital bar and lateral canthal advancements and to increase interorbital distance and anterior cranial fossa volume when utilized in those patients who exhibit the full expression of trigonocephaly, including midline ridging, bifrontal recession, hypotelorbitism, shortened anterior cranial fossa, deficient projection of lateral orbit, and bitemporal narrowing. It is a modification of the supraorbital bar remodeling/advancement procedure as originally described by Marchac with the introduction of a nasofrontal osteotomy and superior osteotomy bone graft and midline miniplate fixation of the supraorbital bar to the nasofrontal junction. Its use in 20 patients has been favorable.     

Evidence for a plasmid conferring salt-tolerance in the plant-root associated,diazotrophKlebsiella sp. NIAB-I

Summary Using analytical and preparative methods, we demonstrated the presence of an indigenous plasmid (pNIAB-I) in a diazotroph,Klebsiella sp. NIAB-I isolated, from the roots of Kallar grass, growing on saline lands in Pakistan. The plasmid is approximately 50 kilobase (kb) in size. Transformation experiments indicated that non-halophilic bacteria such asE. coli K12 strain (MV10) andK. pneumoniae M5AI on acquiring this plasmid become tolerant to high salt (NaCl) and alkaline pH.     

Age-mediated gut microbiota dysbiosis promotes the loss of dendritic cells tolerance

The old age-related loss of immune tolerance inflicts a person with a wide range of autoimmune and inflammatory diseases. Dendritic cells (DCs) are the sentinels of the immune system that maintain immune tolerance through cytokines and regulatory T-cells generation. Aging disturbs the microbial composition of the gut, causing immune system dysregulation. However, the vis-à-vis role of gut dysbiosis on DCs tolerance remains highly elusive. Consequently, we studied the influence of aging on gut dysbiosis and its impact on the loss of DC tolerance. We show that DCs generated from either the aged (DC^Old) or gut-dysbiotic young (DC^Dysbiotic) but not young (DC^Young) mice exhibited loss of tolerance, as evidenced by their failure to optimally induce the generation of Tregs and control the overactivation of CD4⁺ T cells. The mechanism deciphered for the loss of DC^Old and DC^Dysbiotic tolerance was chiefly through the overactivation of NF-κB, impaired frequency of Tregs, upregulation in the level of pro-inflammatory molecules (IL-6, IL-1β, TNF-α, IL-12, IFN-γ), and decline in the anti-inflammatory moieties (IL-10, TGF-β, IL-4, IDO, arginase, NO, IRF-4, IRF-8, PDL1, BTLA4, ALDH2). Importantly, a significant decline in the frequency of the Lactobacillus genus was noticed in the gut. Replenishing the gut of old mice with the Lactobacillus plantarum reinvigorated the tolerogenic function of DCs through the rewiring of inflammatory and metabolic pathways. Thus, for the first time, we demonstrate the impact of age-related gut dysbiosis on the loss of DC tolerance. This finding may open avenues for therapeutic intervention for treating age-associated disorders with the Lactobacillus plantarum.     

Cryopreservation of immature spring wheat zygotic embryos using an abscisic acid pretreatment

Spring wheat (Triticum aestivum L.) zygotic embryos were successfully cryopreserved, without the addition of exogenous cryoprotectants, using only an abscisic acid (ABA) pretreatment. Optimum survival was obtained when embryos were cultured in vitro for 10 days on semisolid Murashige and Skoog (MS) nutrient medium supplemented with 0.5 mg/L (±) ABA prior to cryopreservation. The embryos resumed growth within three days when returned to MS medium devoid of ABA but containing 2mg/L 2,4-dichlorophenoxyacetic acid. The embryogenic calli produced from these embryos exhibited normal plant regeneration on auxin-free media. Changes in dw/fw ratio, as well as the esterified fatty acid and sucrose concentrations correlated positively with the development of tolerance to cryopreservation.NRCC Publication No. 33519     

Effects of photoperiod and temperature on blood feeding,oögenesis and fat body development in the mosquito, Culiseta inornata

In the laboratory, blood feeding rates, oögenesis and fat body development were utilized to assess the effects of photoperiod and temperature in the conditioning of adult female Culiseta inornata for aestivation. Long-day (16L:8D) and short-day (8L:16D) photoperiods were examined in combination with temperatures of 15°C, 20°C, and 25°C. All tested individuals were reared from egg to adult under one of six possible regimes.Blood feeding occurred in approximately 60% of the females subjected to short-day conditions. Females subjected to long-day regimes exhibited gonotrophic concordance (the inhibition of blood feeding), evidenced by a decrease in overall blood-feeding rate to 20%. Inhibition of blood feeding by long-day females decreased in a linear fashion with increasing temperature. No interaction of the effects of photoperiod and temperature upon blood feeding was apparent. Examination of the ovarioles of post-blood feeding females, reared under each of the above conditions, revealed no evidence of gonotrophic dissociation (the inhibition of oögenesis despite continued blood feeding).Fat body hypertrophy occurred in females reared under long-day conditions, whereas hypotrophy of this tissue was apparent in short-day females. No significant difference in fat body development occurred between parous and nulliparous females reared under long-day photoperiod conditions. Short-day blood-fed females reared at 15°C deposited a significantly greater amount of fat than short-day blood fed females reared at 20° and 25°C, and short-day nonbloodfed females reared at 15°, 20°, and 25°C. The primary stimulus for fat body hypertrophy appears to be long-day photoperiod conditions. Temperature exerted little discernible effect upon this process, and there was no interaction between the effects of photoperiod and temperature upon the degree of fat body development.     

Metal tolerance in tissue cultures of anthoxanthum odoratum

Tissue cultures were initiated from one non-tolerant (S20) and two zinc and lead tolerant (T92 and T94) clones of Anthoxanthum odoratum. Growth of callus from the non-tolerant clone was reduced by the presence of zinc, lead, copper and nickel, whereas callus from the two tolerant clones showed no reduction of growth in the presence of zinc and lead but growth was reduced by copper and nickel. The specificity of metal tolerance shown by the parental material was maintained in the callus. Tolerant and non-tolerant callus accumulated similar amounts of zinc and lead.     

Effect of drying period and soil moisture on egg hatch of the tadpole shrimp (Notostraca: Triopsidae).

Tadpole shrimp (Triops spp.) are potential biological control agents against larval mosquitoes in temporary ponds and flood-irrigated fields. In some rice field situations, however, they may become pests that uproot and eat young rice plants. In cursory observations, it has been reported that tadpole shrimp eggs do not readily hatch on flooding when the soil or substrate containing eggs is moist before flooding. The relationship between drying (moisture content) of soil and tadpole shrimp hatch was determined in studies conducted in mesocosms at the University of California Aquatic and Vector Control Research facilities at Riverside and at Oasis in the Coachella Valley of southern California. In laboratory hatching trials, an increase in hatch of Triops longicaudatus (LeConte) with declining soil moisture content was demonstrated (t = 8.4, P less than 0.001; r2 = 0.76). In field trials in mesocosms at Riverside, egg hatch increased with increased drying period and declining soil moisture content (G = 29.8, P less than 0.01). No hatch of eggs occurred after 3 d of drying, when soil moisture content was high, but a high level of hatching occurred after 7 and 14 d of drying, when soil moisture declined to low levels. At Oasis, soil moisture did not decrease with drying time because of porous soil and capillary action of water from adjacent flooded mesocosms and thick vegetation covering the pond bottoms. Therefore, hatch rates at Oasis were not associated with the length of the drying period (G = 35, P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of Bacillus thuringiensis as a biocide of blackfly larvae (Diptera: Simuliidae)

Thirteen strains of Bacillus thuringiensis were bioassayed against late-instar larvae of field-collected Simulium vittatum. All 13 strains caused significant blackfly mortality. The mortalities ranged from 64% for the HD 225 strain to 88% for HD 39 at 10 ppm for a 24-hr exposure period. A minimum 24 hr of exposure to a minimum concentration of 10 ppm was required to produce mortalities approximating 90%. The LC₅₀ values for the HD 39 and HD 225 strains were 1.1 and 1.0 ppm, respectively.