Genic homozygosity in an ancient reptile (Alligator mississippiensis)

Proteins assayed electrophoretically showed variation at only three of 49 presumed genetic loci in alligators from southwestern Louisiana. Average heterozygosity per individual was 0.021±0.012; proportion of polymorphic loci was 0.06. Data on the history, structure, and ecology of this alligator population are consistent with natural selection as the primary factor accounting for this low genetic variability. However, neither a historic population bottleneck nor some genetic mechanism limiting variability can be dismissed as a possible factor.The study was supported by NSF Grant BMS 73-0125 to H.C.D.     

Transmission of Megatrypanum Trypanosomes to Cervus dama by Tabanidae1

Four fallow deer, Cervus dama, became infected with Trypanosoma (Megatrypanum) sp. by oral application of triturated guts from tabanids collected in an area with deer but without any cattle; four control calves remained negative. Upon challenge with triturated guts from tabanids from an area with pastured cattle, the four calves became infected with Trypanosoma (M.) theileri. The prepatent period in deer was five days or less. Haematopota spp. and Tabanus spp. were identified as vectors of the deer trypanosomes. It is concluded that the trypanosomes of C. dama belong to a Megatrypanum species that is not identical with T. theileri.     

Physical mapping of three fruit ripening genes：Endopolygalacturonase,ACC oxidase and ACC synthase from apple（Malus x domestica） in an apple rootstock A106（Malus sieboldii

The apple rootstock,A106(Malus sieboldii),had 17 bivalents in pollen mother cells at meiotic metaphase 1,and 17 chromosomes in a haploid pollen cell.Karyotypes were prepared from root-tip cells with 2n=34 chromosomes,Seven out of 82 karyotypes(8.5%) showed one pari of satellites at the end of the short arm of chromosome 3.C-bands were shown on 6 pairs of chromosomes 2,4,6,8,14,and 16 near the telomeric regions of short arms.Probes for three ripening-related genes from Malus x domestica:endopolygalacturonase(EPG,0.6kb),ACC oxidase(1.2kb),and ACC synthase(2kb)were hybridized in situ to metaphase chromosomes of A106.Hybridization sites for the EPG gene were observed on the long arm of chromosome 14 in 15 out of 16 replicate spreads and proximal to the centromere of chromosomes 6 and 11.For the ACC oxidase gene,hylridization sites were observed in the telomeric region of the short arm of chromosomes 5 and 11 in 87% and 81% of 16 spreads respectively,proxiaml to the centromere of chromosome 1 in 81% of the spreads,and on the long arm of chromosome 13 in 50% of the spreads. Physical mapping of three fruit ripening genes in an apple rootstock A106.Twenty five spreads were studied for the ACC synthase gene and hybridization sites were observed in the telomeric region of the short arm of chromosome 12 in 96% of the spreads.chromosomes 9 and 10 in 76% of the spreads,and chromosome 17 in 56% of the spreads.     

The cytokineplast: purified, stable, and functional motile machinery from human blood polymorphonuclear leukocytes

We examined the formation of motile, chemotactically active, anucleate fragments from human blood polymorphonuclear leukocytes (PMN, granulocytes), induced by the brief application of heat. These granule-poor fragments are former protopods (leading fronts, lamellipodia) that become uncoupled from the main body of the cell and leave it, at first with a connecting filament that breaks and seals itself. The usual random orientation of such filaments can be controlled by preorientation of cells in a gradient of the chemotactic peptide, N-formylmethionylleucylphenylalanine (F-Met-Leu-Phe) (2x10(-9) M- 1x10(-8)). Cytochalsin B, 2.5-5 μg/ml, prevents fragment formation; colchicine, 10(-5) M, does not. In scanning electron micrographs, fragments are ruffled and the cell body rounded up and rather smooth. In transmission electron micrographs, fragments contain microfilaments but lack centrioles and microtubules. Like intact cells, both bound and free fragments can respond chemotactically to an erythrocyte destroyed by laser microirradiation (necrotaxis); the free, anucleate fragments may do so repeatedly, even after having been held overnight at ambient temperatures. We propse the name cytokineplast for the result of this self-purification of motile apparatus. The exodus of the motile machinery from the granulocyte requires anchoring of the bulk of the cell to glass and uncoupling, which may involve heat-induced dysfunction of the centrosome. In ultrastructural studies of the centrosomal region after heat, centriolar structure remains intact, but pericentriolar osmiophilic material appears condensed, and microtubules are sparse. These changes are found in all three blood cell types examined: PMN, eosinophil, and monocyte. Of these, the first two make fragments under our conditions; the more sluggish monocyte does not. Uncoupling is further linked to centrosomal dysfunction by the observation that colchicines-treated granulocytes (10(-5)M, to destroy the centrosome’s efferent arm) make fragments after less heat than controls. If motive force and orientation are specified mainly from the organelle-excluding leading front, then endoplasmic streaming in PMN is a catch-up phenomenon, and microtubules do not provide the vector of locomotion but rather stabilize and orient the “baggage” (nucleus, granuloplasm)—i.e., they prevent fishtailing. Moreover, constraints emanating from the centrosome may now be extended to include, maintenance of the motile machinery as an integral part of the cell.     

In vitro evaluation of native entomopathogenic fungi and neem (Azadiractha indica) extracts on Spodoptera frugiperda

The control of Spodoptera frugiperda is based on synthetic insecticides, so some alternatives are the use of entomopathogenic fungi (EF) and neem extract. The objective of the study was to evaluate in vitro effectiveness of native EF and neem extracts on S. frugiperda larvae. Six EF were identified by DNA sequencing of ITS regions from three EF (Fusarium solani, Metarrhizium robertsii, Nigrospora spherica and Penicillium citrinum). They were evaluated in concentrations of 1 × 10⁸ spores/ mL. In addition, a second bioassay was carried out evaluating only F. solani, M. robertsii and N. sphaerica and the addition of vegetable oil. On the other hand, extraction of secondary metabolites from neem seed (Azadirachta indica) was carried out by performing, mass (g) and solvent volume (mL ethanol and water) combinations, which were subjected to microwaves and ultrasound. Subsequently, these extracts were evaluated in concentrations of 3%, 4% and 5%. A survival analysis was performed for each of the bioassays. With respect to the results of the first bioassay, F. solani obtained a probability of survival of 0.476 on the seventh day, while in the second bioassay, M. robertsii obtained 0.488 survival probability. This suggests that the expected percentage of larvae that stay alive on the sixth day is 48.8%. However, in the evaluation of the neem extract the combination 1:12/70% to 4% caused 84% mortality of larvae. The use of native HE and neem extracts has potential for the control of S. frugiperda.     

GABA receptor modulation of 5-HT neuronal firing: characterization and effect of moderate in vivo variations in glucocorticoid levels

Evidence from electrophysiological studies suggests that 5-HT neuronal firing in the dorsal raphe nucleus (DRN) may be regulated by both GABA(A) and GABA(B) receptors. Here, we addressed the question of whether the activity of individual 5-HT neurons is regulated by both GABA(A) and GABA(B) receptors. In addition, we examined the concentration-response relationships of GABA(A) and GABA(B) receptor activation and determined if GABA receptor regulation of 5-HT neuronal firing is altered by moderate alterations in circulating corticosterone. The activity of 5-HT neurons in the DRN of the rat was examined using in vitro extracellular electrophysiology. The firing of all individual neurons tested was inhibited by both the GABA(A) receptor agonist 4,5,6,7-tetrahydroisoxazolo-[5,4-c]-pyridin-3-ol hydrochloride (THIP) (25 microM) and the GABA(B) receptor agonist baclofen (1 microM). Responses to THIP (5, 10, 25 microM) and baclofen (1, 3, 10 microM) were concentration dependent and attenuated by the GABA(A) and GABA(B) receptor antagonists, bicuculline (50 microM) and phaclofen (200 microM), respectively. To examine the effects of corticosterone on the sensitivity of 5-HT neurons to GABA receptor activation, experiments were conducted on adrenalectomized animals with corticosterone maintained for two weeks at either a low or moderate level within the normal diurnal range. These changes in corticosterone levels had no significant effects on the 5-HT neuronal response to either GABA(A) or GABA(B) receptor activation. The data indicate that the control of 5-HT neuronal activity by GABA is mediated by both GABA(A) and GABA(B) receptors and that this control is insensitive to moderate changes in circulating glucocorticoid levels.     

Holding effects on coliform enumeration in drinking water samples

Standard procedures for analyzing drinking water stress the need to adhere to the time and temperature conditions recommended for holding samples collected for microbiological testing. The National Drinking Water Laboratory Certification Program requires compliance with these holding limits, but some investigators have reported difficulties in meeting them. Research was conducted by standard analytical methods to determine if changes occurred when samples were held at 5 and 22 degrees C and analyzed at 0, 24, 30, and 48 h. Samples were analyzed for coliforms by the membrane filter and fermentation-tube procedures and for heterotrophs by the pour plate method. A total of 17 treated water samples were collected from a large municipal distribution system from August to December 1981, and 12 samples were collected from January to May 1983. The samples were dosed with coliforms previously isolated from the water system, Enterobacter cloacae in 1981 and Citrobacter freundii in 1983. The coliform counts declined linearly over time, and the rates of decline were significant at both 5 and 22 degrees C. Within 24 h at 22 degrees C, levels of E. cloacae and C. freundii decreased by 47 and 26%, respectively, and at 5 degrees C, E. cloacae numbers declined by 23%. Results from these representative laboratory-grown coliforms reinforced those previously obtained with naturally occurring coliforms under the same experimental conditions. Significantly, some samples with initially unacceptable counts (greater than 4/100 ml) met the safe drinking water limits after storage at 24 h at 5 and 22 degrees C and would have been classified as satisfactory.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in microvascular fluid filtration capacity during 120 days of 6 degrees head-down tilt.

We used venous congestion strain gauge plethysmography (VCP) to measure the changes in fluid filtration capacity (K(f)), isovolumetric venous pressure (Pv(i)), and blood flow in six volunteers before, on the 118th day (D118) of head-down tilt (HDT), and 2 days after remobilization (Post). We hypothesized that 120 days of HDT cause significant micro- and macrovascular changes. We observed a significant increase in K(f) from 3.6 +/- 0.4 x 10(-3) to 5.7 +/- 0.9 x 10(-3) ml. min(-1). 100 ml(-1). mmHg(-1) (+51.4%; P < 0.003), which returned to pretilt values (4.0 + 0.4 x 10(-3) ml. min(-1). 100 ml(-1). mmHg(-1)) after remobilization. Similarly, Pv(i) increased from 13.4 +/- 2.1 mmHg to 28.9 +/- 2.8 mmHg (+105.8%; P < 0.001) at D118 and was not significantly different at Post (12.4 +/- 2.6 mmHg). Blood flow decreased significantly from 2.3 +/- 0.3 to 1.3 +/- 0.2 ml. min(-1). 100 ml tissue(-1) at D118 and was found elevated to 3.4 +/- 0.7 ml. min(-1). 100 ml tissue(-1) at Post. We believe that the increased K(f) is caused by a higher microvascular water permeability. Because this may result in edema formation, it could contribute to the alterations in fluid homeostasis after exposure to microgravity.