Secondary structure simulations of twin-arginine signal peptides in different environments

The twin-arginine translocation (Tat) system transports folded proteins across bacterial plasma membranes and the chloroplast thylakoid membrane. A twin-arginine motif in the signal peptide sequence plays a key role in the signal process. In this article we report the results of molecular dynamics simulations on a typical Escherichia coli RR-signal peptide and two mutant variants in both aqueous and trifluoroethanol (TFE) solutions. It has been found that the peptide switches between two distinct states: random coil in water and some helical content in TFE. Our simulations demonstrate that the wild-type peptide is considerably more flexible than either of the mutants in both the solvents investigated. The twin-arginine motif was found to provide a nucleation point for the formation of an -helix in water, but also appears to destabilise -helices in other regions of the peptide when dissolved in TFE

Reduced risk of low weight births among indigent women receiving care from nurse-midwives

STUDY OBJECTIVE—To examine the effect of a comprehensive prenatal and delivery programme administered by nurse-midwives on the risk of low weight births among indigent women.
STUDY DESIGN—Historical prospective study. Birth outcomes among the cohort were compared with all county births during the same period, adjusting for maternal age and race. Results are expressed as relative risks with 95% confidence intervals.
SETTING—An enhanced Medicaid funded pre-natal programme administered by nurse-midwives from 1992 to 1994 in Westchester County, New York.
PARTICIPANTS—Indigent mothers (n=1443), between the ages of 15 and 44, who were residents of Westchester County and indicated having Medicaid or no health care coverage.
RESULTS—There were 1474 live births among cohort mothers. Mean (SD) gestational age was 39.4 (1.9) weeks. Less than 6% of births occurred before 37 weeks gestation. The mean birth weight of cohort infants was 3365.6 (518.6) g. Only 4.1% of the cohort births were less than 2500 g. Compared with all county births, the cohort showed a 41% reduction in the risk of low weight births (RR(lbw)=0.59, 95%CI: 0.46 to 0.73, p<.001 ) and a 56% reduction when compared with county Medicaid births only (RR=0.44, 95%CI: 0.34 to 0.57,( )p<.005) adjusting for maternal age and race. Larger reductions were found for very low weight births.
CONCLUSIONS—Mothers need not be considered at high risk for adverse pregnancy outcomes based on their socioeconomic status alone. Moreover, a comprehensive prenatal programme administered by nurse-midwifes may promote a reduction in adverse pregnancy outcomes among indigent mothers.


Keywords: low birth weight; prenatal care; indigent mothers; nurse-midwif

Reproduction of a South American population of pumpkinseed sunfish Lepomis gibbosus (Linnaeus) (Osteichthyes, Centrarchidae): a comparison with the European and North American populations

The reproductive biology of the introduced pumpkinseed sunfish Lepomis gibbosus (Linnaeus, 1758) in the Custódio's Dam, rio Doce high basin, state of Minas Gerais, Brazil was studied from February/2001 to March/2002 and compared with introduced and native populations. Reproduction occurred almost along the entire period of study with a high frequency of fishes in the advanced ripening/mature and spawned/spent stages. The microscopic analyses indicated that the pumpkinseed sunfish presents multiple spawning. The egg diameter of the Brazilian population is similar to the Spanish, Greek and American ones. The standard length at maturity and the gonadosomatic index of the introduced populations are smaller when compared with native ones. The spawning season of the Brazilian population was the longest among all comparisons made in the present work.<br>Estudou-se de fevereiro/2001 a março/2002 a biologia reprodutiva da exótica perca-sol Lepomis gibbosus (Linnaeus, 1758) na represa do Custódio, bacia do alto rio Doce, Brasil, comparando-a à de populações exóticas e nativas. A reprodução ocorreu praticamente ao longo de todo o período de estudo e a análise microscópica de ovários indicou desova do tipo parcelada para a espécie. O diâmetro ovocitário da população brasileira é semelhante à espanhola, grega e americana. O comprimento padrão na maturidade e o índice gonadossomático de populações introduzidas são menores do que as nativas. O período de desova da população brasileira foi o maior dentre todas as populações analisadas no presente trabalho