Electrophoretic confirmation of the intergeneric hybrid ×Ruttyruspolia (Acanthaceae)

A plant collected in South Africa in the early 1960's has been considered an intergeneric hybrid with the parental taxa beingRuspolia hypocrateriformis (Vahl)Milne-Redhead var.australis Milne-Redhead andRuttya ovata Harv. The intermediate morphology of the plant provided the strongest evidence of its hybrid origin. The natural hybrid, named formally as ×Ruttyruspolia A. Meeuse & de Wet, is highly sterile. Crosses between the two presumed parental taxa produced two plants that are very similar to the putative natural hybrid. We had examined the presumed parental species and the natural and artificial hybrids using enzyme electrophoresis. The two parental species are highly differentiated at genes specifying soluble enzymes; they have a genetic identity of 0.51. They have no common alleles at two genes, and contain alternative alleles in very different frequencies at two loci.Ruttya andRuspolia exhibit both unique and common alleles at two additional genes. The natural and artificially produced plants of ×Ruttyruspolia are identical electrophoretically and contain alleles unique to each of the parental species at two genes. In addition, individuals of ×Ruttyruspolia combine alternative high frequency alleles from each parent at two loci. Allozymes provide strong confirming evidence for the hybrid origin of naturally occurring ×Ruttyruspolia because the products of specific alleles either unique to or highly characteristic of the two putative parental taxa are found combined in ×Ruttyruspolia.     

Succinate metabolism related to lipid synthesis in the housefly Musca domestica L

The metabolism of succinate was examined in the housefly Musca domestica L. The labeled carbons from [2,3-¹⁴C]succinate were readily incorporated into cuticular hydrocarbon and internal lipid, whereas radioactivity from [1,4-¹⁴C]succinate was not incorporated into either fraction. Examination of the incorporation of [2,3-¹⁴C]succinate, [1-¹⁴C]acetate, and [U-¹⁴C]proline into hydrocarbon by radio-gas-liquid chromatography showed that each substrate gave a similar labeling pattern, which suggested that succinate and proline were converted to acetyl-CoA prior to incorporation into hydrocarbons. Carbon-13 nuclear magnetic resonance showed that the labeled carbons from [2,3-¹³C]succinate enriched carbons 1, 2, and 3 of hydrocarbons with carbon-carbon coupling showing that carbons 2 and 3 of succinate were incorporated as an intact unit. Radio-high-performance liquid chromatographic analysis of [2,3-¹⁴C]succinate metabolism by mitochondrial preparations showed that in addition to labeling fumarate, malate, and citrate, considerable radioactivity was also present in the acetate fraction. The data show that succinate was not converted to methylmalonate and did not label hydrocarbon via a methylmalonyl derivative. Malic enzyme was assayed in sonicated mitochondria prepared from the abdomens and thoraces of 1- and 4-day-old insects; higher activity was obtained with NAD⁺ in mitochondria prepared from thoraces, whereas NADP⁺ gave higher activity with abdomen preparations. These data document the metabolism of succinate to acetyl-CoA and not to a methylmalonyl unit prior to incorporation into lipid in the housefly and establish the role of the malic enzyme in this process.     

Nitrification and nitrogen accumulation in the early stages of primary succession on Mt. Fuji

The relationship between nitrification potential and nitrogen accumulation was studied in an early successional sere on Mt. Fuji. Soil organic nitrogen accumulated with the invasion ofPolygonum cuspidatum and successively withMiscanthus oligostachyus and other species. Laboratory incubation experiments showed a higher nitrification potential at theM. oligostachyus state. The numbers of nitrifying bacteria increased with the progress of succession. No significant difference in nitrate reductase activity was found between pioneer and succeeding species. The soil solution at theM. oligostachyus stage contained a lower level of nitrate than rainwater, while that of the bare ground and theP. cuspidatum stage contained a higher nitrate level than rainwater. It was concluded that the high nitrate levels in the soil solution of the bare ground and theP. cuspidatum stage were due to lower nitrate-absorbing activity, leading to loss of nitrogen with precipitation, while the lower nitrate levels at theM. oligostachyus stage when higher nitrification activity occurred were due to higher nitrate-absorbing activity, preventing net loss of nitrogen from the ecosystem.     

Den distribution and den use by the red foxVulpes vulpes japonica in Kyushu

The distribution of dens and den use by the red fox was studied in Kumamoto Prefecture between 1968 and 1982. A total of 80 dens were classified into natal, residential, and temporarily-visited dens. Natal dens comprised 12.4% of all dens. Relative proportions were quite stable for a long period. This indicates a constant number of reproducing females in the area for a considerable length of time. Seasonally the utilization of den showed three peaks in February, May and October. The peaks coincided well with the peaks of reproductive activity of female foxes. The results of multiple regression analysis of distribution of dens with respect to selected environmental parameters around densites indicated that the fox selectively utilize open land, rather than densely vegetated areas. The persistence of dens, the selective utilization by foxes of open land and the sizes of dens were all related to the breeding activities of female foxes inhabiting the area. Reproductive females usually used plural dens (“den group”) in one reproductive season. The numbers of those females occuring in the area were maintained at a steady level for fairy long periods. These indicate that the existence of a stable social relationship between females mediated through occupancy of “den groups.”     

Host immunoglobulin G titre and antibody activity in haemolymph of the tick, Ornithodoros moubata

Immunoglobulin G (IgG) in tick haemolymph was analysed immunochemically and biochemically for its antigenicity, antibody activity and relative concentration in a soft tick, Ornithodoros moubata (Murray) sensu Walton 1962 (Acari: Argasidae). Ouchterlony immunodiffusion tests showed that haemolymph from a tick engorged on rabbit IgG (or human IgG) through an artificial membrane, reacted with anti-rabbit IgG (anti-human IgG) but not with anti-human IgG (anti-rabbit IgG). This indicates that haemolymph of the fed tick contains IgG with a similar antigen specificity to host blood IgG. IgG from tick haemolymph was demonstrated by enzyme immunoassay to have the same antibody activity as ingested IgG. The IgG concentration in tick haemolymph was measured by a quantitative single immunodiffusion test. Changes of IgG titre after a bloodmeal were correlated with IgG activity, which was low for 5 days after a bloodmeal and then suddenly increased. The IgG titre reached a maximum 7 days post-engorgement, and remained high for over 4 months during and after oviposition. 125I-labelled IgG was injected into the tick haemocoel to determine the persistence of IgG in the haemolymph. Recovery of labelled IgG was low at 1 and 3 days, and high at 5, 8 and 16 days after engorgement. The data suggest that IgG in haemolymph disappears quickly soon after engorgement possibly by degradation and/or absorption (adhesion to tissues).     

Immunocytochemical and electron-microscopic investigations of the pineal organ in adult agamid lizards,Uromastix hardwicki

Summary Lacertilian species display a remarkable diversity in the organization of the neural apparatus of their pineal organ (epiphysis cerebri). The occurrence of immunoreactive S-antigen and opsin was investigated in the retina and pineal organ of adult lizards, Uromastix hardwicki. In this species, numerous retinal photoreceptors displayed S-antigen-like immunoreactivity, whereas only very few pinealocytes were labeled. Immunoreactive opsin was found neither in retinal photoreceptors nor in pinealocytes. Electron microscopy showed that all pinealocytes of Uromastix hardwicki resemble modified pineal photoreceptors. A peculiar observation is the existence of a previously undescribed membrane system in the inner segments of these cells. It is evidently derived from the rough endoplasmic reticulum but consists of smooth membranes. The modified pineal photoreceptor cells of Uromastix hardwicki were never seen to establish synaptic contacts with somata or dendrites of intrapineal neurons, which are extremely rare. Vesiclecrowned ribbons are prominent in the basal processes of the receptor cells, facing the basal lamina or establishing receptor-receptor and receptor-interstitial type synaptoid contacts. Dense-core granules (60–250 nm in diameter) speak in favor of a secretory activity of the pinealocytes. Attention is drawn to the existence of receptor-receptor and receptor-interstitial cell contacts indicating intramural cellular relationships that deserve further study.Supported by the Deutsche Forschungsgemeinschaft (Ko 758/31) and the Deutscher Akademischer Austauschdienst (Senior DAAD Research Fellowship to M.A.H.)     

Chick brain glutamine synthetase and Mn2+−Mg2+ interactions

Glutamine synthetase (GS) from the chick brain was purified to apparent homogeneity by ammonium sulfate fractionation followed by affinity chromatography, electrofocusing and Sephadex G-150 chromatography. The purified enzyme showed a single band on sodium dodecyl sulfate analysis in polyacrylamide gel. By sedimentation equilibrium analysis and gel electrophoresis analysis, it was shown that the enzyme has a subunit molecular weight of 45,000 and a native molecular weight of 364,000, which is consistent with an octameric structure. Sedimentation analysis in the presence of Mg²⁺ revealed three different forms of macromolecules corresponding respectively to a monomer, a tetramer and an octamer. Among eight cations tested (Ca²⁺, Co²⁺, Fe²⁺, Li⁺, Mg²⁺, Mn²⁺, Ni²⁺, Zn²⁺) only Co²⁺, Mg²⁺ and Mn²⁺ supported GS activity; the order of activatory ability was Mg²⁺>Co²⁺>Mn²⁺. The maximum activating effect of Mn²⁺ occurs only within a very narrow range of concentration: with an excess of cation causing strong inhibition of GS activity. For each cation, maximal GS activity occurs at a defined cation/ATP ratio. A regulatory system in which Mn²⁺, modulates the Mg²⁺ dependent GS activity, is proposed; such cation interactions may be of significance in the intracellular control of glutamine synthesis.     

Extracellular enzymes of mycobacteria

Abstract Extracellular enzymes were studied in different mycobacteria using a plate substrate assay. All the pathogenic mycobacteria included in the study showed the presence of protease, while lipase, ribonuclease, mucinase and β-lactamase could also be detected in some strains. In contrast, no protease was detected in the 3 saprophytic mycobacteria studied. DNase was not detected in any of the species studied. Thus, the demonstration of extracellular enzymes, in particular of protease, in mycobacteria may be relevant in understanding their role in pathogenicity.     

A Chronobiologic Approach to Ethanol and Acidified Aspirin Injury of the Gastric Mucosa in the Rat

Several models of erosive peptic disease have used drug-induced lesions to examine protective mechanisms of the gastric mucosa. Physiological processes such as acid secretion, motility, or epithelial cell turnover have circadian rhythms which may modulate the susceptibility of the gastric mucosa to injury. In this review are described recent studies which demonstrated that susceptibility to gastric mucosal injury by acidified aspirin and absolute ethanol varied with the phases of the light-dark cycle. Acidified aspirin caused significantly more gastric mucosal lesions when administered early in the light phase compared to administration early in the dark phase. The differences in susceptibility were not altered by pretreatment conditions such as immobilization or length of the fasting period. Absolute ethanol also caused significantly greater gastric mucosal injury when administered in the light than in the dark phase, but this difference was only evident in rats immobilized during the pretreatment fasting period. Further studies are needed to correlate circadian susceptibility to drug-induced gastric mucosal injury with physiological defense mechanisms. Careful attention to circadian timekeeping may allow us to refine therapy to optimize physiological defense mechanisms in the stomach.     

Isolation and characterisation of transposon-induced mutants of Erwinia carotovora subsp. atroseptica exhibiting reduced virulence

Summary The blackleg pathogen Erwinia carotovora subsp. atroseptica (Eca) causes an economically important disease of potatoes. We selected a genetically amenable Eca strain for the genetic analysis of virulence. Tn5 mutagenesis was used to generate nine mutants which exhibited reduced virulence (Rvi^-) of strain SCRI1043. Following physiological characterisation, mutants were divided into three classes: (1) auxotrophs; (2) extracellular enzyme mutants; and (3) a growth rate mutant. The isolation of these Rvi^- mutants has allowed us to consider some factors that affect Eca virulence.