Temporal study of the staphylococci and micrococci of normal infant skin

Staphylococcus and Micrococcus populations were collected from the healthy skin of 10 infant subjects. Infants were sampled from 1 day to 32 weeks of age. Species were characterized by approximately 30 different morphological, physiological, and biochemical characters. Staphylococci were the predominant inhabitants of normal skin, whereas micrococci were found only occasionally in this environment. Staphylococcus epidermidid, S. haemolyticus, and S. hominis were the predominant and persistent staphylococci. These species constituted a high percentage of the total aerobic bacterial flora of infant skin. Micrococcus luteus and M. kristinae were the prevalent micrococci found on infant skin. Only limited correlation between Staphyloccus and Micrococcus populations and infant age or body area sampled was indicated by this study.     

Onchocerciasis, malaria and trypanosomiasis in three resettlement schemes in western Ethiopia.

Epidemiological studies were carried out among 180 randomly chosen settler and 180 non-settler households in the three resettlement schemes of Kishe, Gera and Didessa located in river valleys and highland areas of Illubabor Administrative Region in western Ethiopia. Up to 49% of the indigenous populations (in Kishe) and 0.9% of the settlers had onchocerciasis, with a mean density of 13.6 filariae per slide/skin snip for indigenous people and 9.4 for settlers. Onchocerciasis prevalence rates were higher in males than females and were highest in the 20-59 age group. In the Kishe scheme, rates were inversely related to distance between residences and probable forest/stream habitat of Simulium damnosum. No onchocerciasis transmission appears to occur in the Gera scheme at 1,950 meters altitude, apparently due to the absence of suitable vectors. Eight of 622 (1.2%) persons had malaria (P. vivax and P. falciparum). The most common man-biting anophelines were A. gambiae and A. funestus. No human trypanosomiasis cases were found but high livestock mortality was reported by local populations in the lowland schemes of Kishe and Didessa.     

Demonstration of a beta-casomorphin immunoreactive material in the plasma of newborn calves after milk intake

Blood was collected from newborn calves before and after their first milk intake after birth; extracts of plasma were assayed by radioimmunoassay for the presence of beta-casomorphin-7 immunoreactive materials. No beta-casomorphin immunoreactivity was found in samples collected before milk ingestion; however, in samples collected after milk ingestion a beta-casomorphin-7 immunoreactive material was detected. Chromatographic characterization showed that this material was not identical with beta-casomorphin-7 but might rather represent a precursor thereof. The material proved resistant to enzymatic attack during a 30-min incubation period at 37 degrees C in the plasma of newborn calves, whereas beta-casomorphin-7 was degraded under these conditions. A physiological significance of beta-casomorphin-7 eventually cleaved from such a precursor material at any site in the newborn mammal is suggested.     

Ion balance in tomato cultivars differing in salt tolerance. I. Sodium and potassium accumulation and fluxes under moderate salinity

The magnitude of sodium and potassium fluxes in Lycopersicon escutentum cuhivars Ace and Edkawi (Edkawi is considered more sait-tolerant I was evaluated in planls grown for 10 days in aerated Hoagland solution with the addition of 25 or 100 mM NaCl. Ion accumulatiun in different plant pans, ion concentration in xylem exudate. transpiration and membrane leakiness were measured. Both cultivars responded very similarly to these levels of salinity in terms of growth. No conspicuous differences in membrane leakiness were observed. Net uprake rates were calculated from ion contents data. Potassium uptake rates were lower in salinized planls than in controls, especially in cv. Aee. Potassium/sodium selectivity ratios were much higher in Edkawi than in Ace. and higher in shoot uptake rates than in xy lem exudate. This indicates that Edakw i has a higher capacity to retain potassium under salinity, a character which could contribute to its salt-tolerance.     

Human appropriation of net primary production as driver of change in landscape-scale vertebrate richness

Aim

Land use is the most pervasive driver of biodiversity loss. Predicting its impact on species richness (SR) is often based on indicators of habitat loss. However, the degradation of habitats, especially through land-use intensification, also affects species. Here, we evaluate whether an integrative metric of land-use intensity, the human appropriation of net primary production, is correlated with the decline of SR in used landscapes across the globe.

Location

Global.

Time period

Present.

Major taxa studied

Birds, mammals and amphibians.

Methods

Based on species range maps (spatial resolution: 20 km × 20 km) and an area-of-habitat approach, we calibrated a “species–energy model” by correlating the SR of three groups of vertebrates with net primary production and biogeographical covariables in “wilderness” areas (i.e., those where available energy is assumed to be still at pristine levels). We used this model to project the difference between pristine SR and the SR corresponding to the energy remaining in used landscapes (i.e., SR loss expected owing to human energy extraction outside wilderness areas). We validated the projected species loss by comparison with the realized and impending loss reconstructed from habitat conversion and documented by national Red Lists.

Results

Species–energy models largely explained landscape-scale variation of mapped SR in wilderness areas (adjusted R²-values: 0.79–0.93). Model-based projections of SR loss were lower, on average, than reconstructed and documented ones, but the spatial patterns were correlated significantly, with stronger correlation in mammals (Pearson's r = 0.68) than in amphibians (r = 0.60) and birds (r = 0.57).

Main conclusions

Our results suggest that the human appropriation of net primary production is a useful indicator of heterotrophic species loss in used landscapes, hence we recommend its inclusion in models based on species–area relationships to improve predictions of land-use-driven biodiversity loss.     

Induced responses in three tropical dry forest plant species – direct and indirect effects on herbivory

Induced changes in plant quality are hypothesized to reduce herbivore numbers and subsequent damage to the plant. The resultant decrease in herbivory may be due to direct negative impacts on herbivores, through the reduction in foliage quality as food, or due to indirect effects of plant-induced traits interacting with the third trophic level, increasing predation and parasitism rates on herbivores. The relative importance of induced responses as direct and/or indirect defenses has not been evaluated in natural systems. Moreover, few studies have evaluated the influence of early-season damage on late-season herbivory in natural systems, particularly in the tropics. The presence of induced responses and subsequent impact on folivory as a consequence of early-season damage were evaluated in three plant species ( Croton pseudoniveus , Bursera instabilis and Piper stipulaceum ) in a tropical dry forest in Mexico. A two-factorial experiment was applied to determine if induced responses influenced subsequent herbivory directly, by reducing foliage quality, or indirectly, through their interaction with parasitoids and predatory arthropods. Plants from all three species with reduced early-season damage had higher herbivory rates through the rest of the growing season, compared to plants that were damaged during leaf expansion. Chemical analyses showed that early-season damage induced the production of total phenolics and condensed tannins for C. pseudoniveus and B. instabilis , respectively. The mechanism by which these compounds affected subsequent herbivory was most likely by directly reducing foliage quality as food for herbivores, given that predatory arthropods and parasitoids had no effects on herbivory in this study. I conclude that early-season damage in these three species influenced later-season herbivory through the induction of plant responses that may act to reduce plant quality as food for herbivores.     

Temporal study of the staphylococci and micrococci of normal infant skin.

Staphylococcus and Micrococcus populations were collected from the healthy skin of 10 infant subjects. Infants were sampled from 1 day to 32 weeks of age. Species were characterized by approximately 30 different morphological, physiological, and biochemical characters. Staphylococci were the predominant inhabitants of normal skin, whereas micrococci were found only occasionally in this environment. Staphylococcus epidermidid, S. haemolyticus, and S. hominis were the predominant and persistent staphylococci. These species constituted a high percentage of the total aerobic bacterial flora of infant skin. Micrococcus luteus and M. kristinae were the prevalent micrococci found on infant skin. Only limited correlation between Staphyloccus and Micrococcus populations and infant age or body area sampled was indicated by this study.     

Agarose gel electrophoresis and restriction endonuclease analysis of largeStaphylococcus plasmids

Preliminary studies using an improved method for the agarose gel electrophoresis of semipurified, cleared lysates of staphylococci have indicated some distinct differences in plasmid composition between the coagulase-positive speciesStaphylococcus aureus andStaphylococcus intermedius, and various coagulase-negative species. Penicillinase-positive strains ofS. intermedius andS. simulans did not carry large penicillinase plasmids like most penicillinase-positive strains ofS. aureus. Most coagulase-negative species examined demonstrated complex plasmid profiles. Codigestion by the restriction endonucleasesHaeIII andHpaI offered a useful approach for “fingerprinting” large plasmids from various strains and species.     

Sulfur amino acid auxotrophy in Micrococcus species isolated from human skin.

Since methionine and (or) cysteine are required by a large percentage of natural auxotrophic Micrococcus strains isolated from human skin, investigations were directed to determine the specific enzymes affected in sulfur amino acid biosynthesis. Known intermediates in the interrelated cysteine and methionine biosynthetic pathways were tested as growth stimulants. Based on these growth studies, sulfur amino acid auxotrophs were grouped into three cysteine classes and five methionine classes. Selected auxotrophs of M. luteus had deficiencies in ATP sulfurylase (EC 2.7.7.4) and adenosine-5-sulfatophosphate (APS) kinase (EC 2.7.1.25), sulfite reductase (EC 1.8.1.2), serine transacetylase (EC 2.3.1.30), or beta-cystathionase (EC 4.4.1.8) activity; auxotrophs of M. lylae had deficiencies in sulfite reductase and serine transacetylase, beta-cystathionase, or N5, N10-methyltetrahydrofolate reductase (EC 1.1.1.68) activity; all auxotrophs of M. sedentarius tested had deficiencies in N5,N10-methyltetrahydrofolate reductase activity; auxotrophs of M. nishinomiyaensis had deficiencies in adenosine-3-phosphate-5-sulfatophosphate (PAPS) reductase, sulfite reductase, serine transacetylase, or N5,N10-methyltetrahydrofolate reductase activity; auxotrophs of M. varians had deficiencies in APS kinase, PAPS reductase, sulfite reductase, homoserine omicron-transsuccinylase, beta-cystathionase, or N5,N10-methyltetrahydrofolate reductase activity; auxotrophs of M. kristinae had deficiencies in serine transacetylase or cystathionine-gamma-synthase (EC 4.2.99.9) activity; auxotrophs of M. roseus had deficiencies in PAPS reductase, sulfite reductase, or serine transacetylase activity. Results of studies with various mutagens suggested that sulfur amino acid auxotrophy was primarily the result of a single base substitution in usually one or two of the genes controlling biosynthesis. A preliminary study of the amino acid composition of sweat suggested that this important source of nutrients does not contain adequate amounts of cysteine for the growth of cysteine auxotrophs but contains methionine that may be utilized in place of cysteine.