POSSIBLE SOURCE OF SECONDARY INVADING STAPHYLOCOCCI IN MICE EXPOSED TO ACUTE COLD

Miraglia, Gennaro J. (Bryn Mawr College, Bryn Mawr, Pa.) and L. Joe Berry. Possible source of secondary invading staphylococci in mice exposed to acute cold. J. Bacteriol. 85:345-348. 1963.-In an effort to determine the origin of the staphylococci known to invade the deep tissues (liver, spleen, kidneys, lungs, and heart) of mice exposed continuously to 5 C in individual compartments without bedding, the intestinal tract was freed of these organisms, as judged by absence of growth when fecal suspensions were inoculated into selective media. Substitution of 0.01 n hydrochloric acid for drinking water eliminated staphylococci within a few days, yet the incidence of tissue invasion was unaltered. The coagulase-negative strains normally present in feces and in tissues persisted in tissues even though the intestine was seeded with a coagulase-positive strain by feeding contaminated food. Cultures from the external nares continued unaltered. This suggests that the respiratory tract is a possible origin of the staphylococci found in tissues of the cold-stressed mice.     

GENETIC VARIATION AND JUVENILE SURVIVAL IN RED DEER

The survival of red deer (Cervus elaphus L.) calves to two years of age was examined in relation to electrophoretic variation in a population on the Scottish island of Rhum. Survival was analyzed using logistic analysis in which the “phenotypic” factors birth weight, birth date, subdivision of the study area, cohort, and sex, which affect the probability of a calf's survival, were taken into account. All three polymorphic loci examined, Mpi, Idh-2, and Trf (each with two detected alleles) are significantly associated with juvenile survival. At Mpi, there is selection against one allele, f (or an allele at a linked locus), and there are indications that this effect is stronger in females than males. For Idh-2, overall, the heterozygote class survives better than the two homozygotes, which survive equally well. However, again there is a difference between the sexes; female heterozygotes survive much better than homozygotes, whereas male homozygotes survive better than heterozygotes, and the difference in survival is smaller. Furthermore, there is an interaction involving Mpi, Idh-2, and survival in which Mpi^f carriers that are also Idh-2 homozygotes survive very badly compared with other Mpi-Idh-2 combinations, which all survive equally well. For Trf, the heterozygote class survives best, and there is also a difference in survival between the two homozygote classes. Genotype frequencies in the adult population are consistent with the results for calf survival, in that the Mpi^f frequency is lower in succeeding cohorts of surviving adults, whereas no significant gene frequency change is apparent for Idh-2 or Trf.     

Smoking and the sudden infant death syndrome: results from 1993-5 case-control study for confidential inquiry into stillbirths and deaths in infancy. Confidential Enquiry into Stillbirths and Deaths Regional Coordinators and Researchers.

OBJECTIVE--To investigate the effects of exposure to tobacco smoke and of parental consumption of alcohol and illegal drugs as risk factors for the sudden infant death syndrome after a national risk reduction campaign which included advice on prenatal and postnatal avoidance of tobacco smoke. DESIGN--Two year population based case-control study. Parental interviews were conducted for each infant who died and four controls matched for age and date of interview. SETTING--Three regions in England with a total population of 17 million people. SUBJECTS--195 babies who died and 780 matched controls. RESULTS--More index than control mothers (62.6% v 25.1%) smoked during pregnancy (multivariate odds ratio = 2.10; 95% confidence interval 1.24 to 3.54). Paternal smoking had an additional independent effect when other factors were controlled for (2.50; 1.48 to 4.22). The risk of death rose with increasing postnatal exposure to tobacco smoke, which had an additive effect among those also exposed to maternal smoking during pregnancy (2.93; 1.56 to 5.48). The population attributable risk was over 61%, which implies that the numbers of deaths from the syndrome could be reduced by almost two third if parents did not smoke. Alcohol use was higher among index than control mothers but was strongly correlated with smoking and on multivariate analysis was not found to have any additional independent effect. Illegal drug use was more common among the index parents, and paternal use of illegal drugs remained significant in the multivariate model (4.68; 1.56 to 14.05). CONCLUSIONS--This study confirms the increased risk of the sudden infant death syndrome associated with maternal smoking during pregnancy and shows evidence that household exposure to tobacco smoke has an independent additive effect. Parental drug misuse has an additional small but significant effect.     

Mapping and characterization of mangrove plant communities in Hong Kong

Ecological surveys were carried out to investigate the distribution and characterization of remaining mangrove stands in Hong Kong. The field studies indicate that 43 mangrove stands, excluding Mai Po Nature Reserve, still remained along the coastline of Hong Kong despite tremendous reclamation and development which occurred in the past 40 years. Most mangrove stands were found in Deep Bay (western part)and Sai Kung District (eastern coasts). The total areas occupied by these mangrove stands were 178 ha,varying from a very small stand (with 1–2 mangrove shrubs) to fairly extensive mangroves in Deep Bay (> 10 ha). It appeared that mangrove stands located in Deep Bay area were larger than those in the eastern coasts. Twenty plant species were identified from these stands, with 13 being exclusive or associate mangrove species. The major constituent species were Kandelia candel, Aegiceras corniculatum, Excoecaria agallocha and Avicennia marina. Rare species such as Heritiera littoralis were only found in a few mangrove stands. Out of the 43remaining mangrove stands, 23 were more worthwhile for conservation and their plant community structures were further investigated by transect and quadrat analyses. The importance values (sum of relative abundance,frequency and dominance) show that K. candel was the most dominant species. Species richness and Simpson's indices together with tree height, tree density and canopy area fluctuated significantly between mangrove stands. These values were used to prioritize the conservation potential of the remaining mangrove stands in Hong Kong. This revised version was published online in August 2006 with corrections to the Cover Date.     

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

Bottle feeding and the sudden infant death syndrome.

OBJECTIVE--To determine whether the risk of the sudden infant death syndrome is increased in bottle fed babies. DESIGN--Population based case-control study matching for age and time. SUBJECTS--All babies aged 1 week to 1 year dying of sudden infant death syndrome during November 1987 to April 1989 or February 1990 to June 1991 and two live controls. SETTING--Avon and north Somerset. MAIN OUTCOME MEASURES--Breast or bottle feeding, sleeping position, maternal smoking, parental employment, and length of gestation. RESULTS--Compared with being fully breast fed, the crude odds ratio for sudden infant death in fully bottle fed babies was 3.1 and for mixed breast and bottle fed babies 1.5. These odds ratios fell to 1.8 (95% confidence interval 0.7 to 4.8) and 1.2 (0.5 to 2.7) respectively after maternal smoking, parental employment, preterm gestation, and sleeping position had been adjusted for. Sleeping position partly masked the effect of being bottle fed on sudden infant death as breast fed babies were more likely to have slept prone than bottle fed babies. CONCLUSIONS--Bottle feeding is not a significant independent risk factor for the sudden infant death syndrome. Patterns of maternal smoking, preterm gestation, and parental employment status account for most of the apparent association with bottle feeding.     

Identification of Extracellular Carbonic Anhydrase of Chlamydomonas reinhardtii

We have examined the induction of carbonic anhydrase activity in Chlamydomonas reinhardtii and have identified the polypeptide responsible for this activity. This polypeptide was not synthesized when the alga was grown photoautotrophically on 5% CO₂, but its synthesis was induced under low concentrations of CO₂ (air levels of CO₂). In CW-15, a mutant of C. reinhardtii which lacks a cell wall, between 80 and 90% of the carbonic anhydrase activity of air-adapted cells was present in the growth medium. Furthermore, between 80 and 90% of the carbonic anhydrase is released if wild type cells are treated with autolysin, a hydrolytic enzyme responsible for cell wall degradation during mating of C. reinhardtii. These data extend the work of Kimpel, Togasaki, Miyachi (1983 Plant Cell Physiol 24: 255-259) and indicate that the bulk of the carbonic anhydrase is located either in the periplasmic space or is loosely bound to the algal cell wall. The polypeptide associated with carbonic anhydrase activity has a molecular weight of approximately 37,000. Several lines of evidence indicate that this polypeptide is responsible for carbonic anhydrase activity: (a) it appears following the transfer of C. reinhardtii from growth on 5% CO₂ to growth on air levels of CO₂, (b) it is located in the periplasmic space or associated with the cell wall, like the bulk of the carbonic anhydrase activity, (c) it binds dansylamide, an inhibitor of the enzyme which fluoresces upon illumination with ultraviolet light, (d) antibodies which inhibit carbonic anhydrase activity only cross-react with this 37,000 dalton species.     

Photosynthetic response and adaptation to high temperature in desert plants : a comparison of gas exchange and fluorescence methods for studies of thermal tolerance

The temperature threshold for the onset of irreversible loss of photosynthetic capacity of leaves was examined in studies of net CO₂ exchange and by chlorophyll fluorescence techniques. Close agreement was found between the temperature threshold for a dramatic increase in the fluorescence of chlorophyll from intact leaves and the leaf temperature at which the capacity for photosynthetic CO₂ fixation (measured at rate saturating light intensity by infrared gas analysis) began to be temperature unstable (i.e. decline with time of exposure to a constant temperature). This decline in CO₂ uptake was not a result of a stomatal response yielding a reduced intercellular CO₂ concentration at high temperature, and it is interpreted as an indication of progressive damage to some essential component(s) of the leaf. The temperature-dependent change in chlorophyll fluorescence apparently also indicated the onset of this damage. The fluorescence assay could be conducted with discs of leaves collected from remote locations and kept moist while they were transported to a central location, allowing assessment of the high temperature tolerance of leaves which developed under natural field conditions. These assays were verified using a mobile laboratory to study gas exchange of attached leaves in situ. The high temperature sensitivity of leaves of plants growing under natural conditions were similar to those of the same species grown in controlled environments of similar thermal regimes. High temperature in controlled environment studies brought about acclimation responses which increased the threshold for high temperature damage as measured by gas exchange. Studies of fluorescence versus temperature confirmed that this method could be used to quantify these responses, and permitted the kinetics of the acclimation response to be examined. Gas exchange studies, while providing similar estimates of thermal stability, required more time, more elaborate instrumentation, and are particularly difficult to conduct with field plants growing in situ.