They're All My Children: Foster Mothering in America

They're All My Children: Foster Mothering in America. Danielle F. Wozniak. New York: NYU Press, 2002. + 245 pp.     

Global analysis of a model of plasmid-bearing,plasmid-free competition in a chemostat

A model of competition between plasmid-bearing and plasmid-free organisms in a chemostat was proposed in a paper of Stephanopoulis and Lapidus. The model was in the form of a system of nonlinear ordinary differential equations. Such models are relevant to commercial production by genetically altered organisms in continuous culture. The analysis there was local (using index arguments). This paper provides a mathematically rigorous analysis of the global asymptotic behavior of the governing equations in the case of uninhibited specific growth rate.Research supported by the National Council of Science, Republic of ChinaResearch supported by National Science Foundation Grant, DMS-9204490Research supported by the Natural Science and Engineering Council of Canada. This author's contribution was made while on research leave visiting the Department of Ecology and Evolutionary Biology at Princeton University. She would especially like to thank Simon Levin for his guidance as well as for providing an exceptional working environment     

Biology of the microsporidan parasite Pleistophora crangoni n. sp. in three species of crangonid sand shrimps

The microsporidium Pleistophora crangoni n. sp. is a common parasite of Crangon franciscorum, C. nigricauda, and C. stylirostris in the vicinity of Yaquina Bay, Oregon. Characteristics of the parasite are described. Skeletal muscle was the only host tissue infected. The seasonal prevalence and intensity of the parasite in crangonids are described, based on examination of 1556 C. franciscorum, 3877 C. nigricauda, and 1674 C. stylirostris collected at monthly intervals from June 1975 through June 1976. Prevalence in C. franciscorum and C. stylirostris increased through the autumn and reached winter peaks of 30.3 and 41.0%, respectively, then decreased in the spring. Prevalence in C. nigricauda remained below 8% through the year. Intensity increased with size of the shrimps in the three species. Infection experiments and field observations suggest that only very young shrimps are susceptible to infection during a relatively short period during the summer months. Following natural infection, the parasite spreads within the host, indicating repeated schizogonic cycles. Parasitic castration was indicated by the absence of gravid infected female shrimps and was confirmed by histological examination. Ovaries of infected shrimps did not develop beyond a very early stage. A shift in sex ratio toward females in infected shrimps indicates that the parasite may influence sex determination. Shrimps showed little cellular response to infection. Only rarely in heavily infected shrimps was encapsulation of parasite cysts observed; necrotic tissue was occasionally observed. Infected shrimps usually succumbed before uninfected shrimps when subjected to oxygen stress. The collection of infected shrimps that were unusually large may indicate that these individuals grew faster or lived longer than uninfected shrimps.     

Variation of cooling rate and concentration of dimethyl sulfoxide on rabbit kidney function

Rabbit kidney function was assessed in vitro after cryoprotection with either 3 or 4 M dimethyl sulfoxide. The introduction and removal of the cryoprotectant was carried out in a stepwise progressive manner and the removal in a stepwise progressive manner with hypertonic mannitol solutions. This in vitro model can be shown to respond to various ischemic-like states resulting in poor or absent function. Active tubular transport can be demonstrated. It has been used by many authors as an intermediate step prior to the ultimate test of reimplant and contralateral nephrectomy. Variations in the rate of cooling at cryoprotection levels of 3 and 4 M dimethyl sulfoxide concentration (Me2SO) were carried out. In general, at 3 M concentration of Me2SO, creatinine clearance, sodium and glucose reabsorption are preserved with a fair degree of success after cooling to -10, -15, and -20 degrees C in our model, when the rate of cooling to these levels is 1.0 degree C/min. When a cooling rate of 0.5 degree C/min is used, renal function is significantly reduced whether the final temperature is -10, -15, or -20 degrees C. Control rabbit kidneys will tolerate 4 M concentration of Me2SO and give fairly good function. When cooled to -15 or -20 degrees C, there is poor function at 0.1 and 0.5 degrees C/min. Fair function is obtained at the rate of 1 degree C/min to -10 degrees C. Therefore, at cryoprotectant levels of 3 and 4 M Me2SO, kidney function as assayed by in vitro perfusion, is better when the cooling rate is 1.0 degree C/min.     

Identification of two mosquitocidal Bacillus cereus strains showing different host ranges

Mosquitocidal bacteria, M413 and C32 have been isolated from sediment samples collected from woodland and ditch, respectively. Gas chromatographic analysis of fatty acids methyl esters (GC-FAME) and 16S rRNA gene sequence alignment results showed these isolates belong to Bacillus cereus. The SDS-PAGE analysis of sporulated cultures of both isolates showed two major bands very similar in size. Interestingly, however, M413 is mainly toxic to 4th instars of Ochlerotatus taeniorhynchus whereas C32 is to those of Culex quinquefasciatus.     

Endotoxin priming of neutrophils requires NADPH oxidase-generated oxidants and is regulated by the anion transporter ClC-3

Several soluble mediators, including endotoxin, prime neutrophils for an enhanced respiratory burst in response to subsequent stimulation. Priming of neutrophils occurs in vitro, and primed neutrophils are found in vivo. We previously localized the anion transporter ClC-3 to polymorphonuclear leukocytes (PMN) secretory vesicles and demonstrated that it is required for normal NADPH oxidase activation in response to both particulate and soluble stimuli. We now explore the contribution of the NADPH oxidase and ClC-3 to endotoxin-mediated priming. Lipooligosaccharide (LOS) from Neisseria meningitidis enhances the respiratory burst in response to formyl-Met-Leu-Phe, an effect that was impaired in PMNs lacking functional ClC-3 and under anaerobic conditions. Mobilization of receptors to the cell surface and phosphorylation of p38 MAPK by LOS were both impaired in PMN with the NADPH oxidase chemically inhibited or genetically absent and in cells lacking functional ClC-3. Furthermore, inhibition of the NADPH oxidase or ClC-3 in otherwise unstimulated cells elicited a phenotype similar to that seen after endotoxin priming, suggesting that basal oxidant production helps to maintain cellular quiescence. In summary, NADPH oxidase activation was required for LOS-mediated priming, but basal oxidants kept unstimulated cells from becoming primed. ClC-3 contributes to both of these processes.     

Localization and replication of the systemic lupus erythematosus linkage signal at 4p16: interaction with 2p11, 12q24 and 19q13 in European Americans

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by both population and phenotypic heterogeneity. Our group previously identified linkage to SLE at 4p16 in European Americans (EA). In the present study we replicate this linkage effect in a new cohort of 76 EA families multiplex for SLE by model-free linkage analysis. Using densely spaced microsatellite markers in the linkage region, we have localized the potential SLE susceptibility gene(s) to be telomeric to the marker D4S2928 by haplotype construction. In addition, marker D4S394 showed marginal evidence of linkage disequilibrium with the putative disease locus by the transmission disequilibrium test and significant evidence of association using a family-based association approach as implemented in the program ASSOC. We also performed both two-point and multipoint model-based analyses to characterize the genetic model of the potential SLE susceptibility gene(s), and the lod scores both maximized under a recessive model with penetrances of 0.8. Finally, we performed a genome-wide scan of the total 153 EA pedigrees and evaluated the possibility of interaction between linkage signals at 4p16 and other regions in the genome. Fourteen regions on 11 chromosomes (1q24, 1q42, 2p11, 2q32, 3p14.2, 4p16, 5p15, 7p21, 8p22, 10q22, 12p11, 12q24, 14q12, 19q13) showed evidence of linkage, among which, signals at 2p11, 12q24 and 19q13 also showed evidence of interaction with that at 4p16. These results provide important additional information about the SLE linkage effect at 4p16 and offer a unique approach to uncovering susceptibility loci involved in complex human diseases.