A middle-affinity estrogen-specific binding protein in livers of vitellogenic and nonvitellogenic Xenopus laevis

Administration of estradiol-17β to male Xenopus laevis evokes massive liver synthesis of the egg yolk precursor protein, vitellogenin, and its cognate mRNA. Since previous experiments had implicated only a nuclear estrogen receptor in vitellogenesis, we examined Xenopus liver cytosol for other estrogen-binding proteins. Cytoplasmic extracts from unstimulated Xenopus liver contain high levels (approximately 500,000 sites/cell) of an estrogen-specific binding protein. This protein exhibits a K_d of approximately 4 × 10^?8M for estradiol-17β, binds estrogenic steroids only, and has a sedimentation coefficient in the range 2–3 S. It is not a classical estrogen receptor, as it does not translocate into the nucleus following estrogen administration. We discuss possible functions of this protein, which include a role in the ontogeny of the vitellogenic response, and in the cytoplasmic transport and storage of estrogen.     

Epstein-Barr virus co-reconstituted with Sendai virus envelopes infects Epstein-Barr virus-receptor negative cells

Epstein-Barr virus (EBV) was co-reconstituted with Sendai virus envelopes. The reconstituted "hybrid' virus could bind and penetrate into EBV-receptor negative cells. Using this approach, T-cell-derived human and mouse leukemia cells, human T-lymphocytes and mouse spleen cells were successfully infected as judged by the induction of EBV-determined antigens and stimulation of DNA synthesis. The T-cell-derived human leukemia line Molt-4, that can absorb EBV but without virus penetration, could be also infected by the reconstituted EBV.     

The influence of females on the initiation of female-to-male sex change in a coral reef fish

In the protogynous coral reef fish Anthias squamipinnis (Peters), all males are sex-reversed females. A sexually mature female can be induced to change sex by removing a male from her social group. The influence of non-sex-changing females on the initiation of sex change was evaluated in 109 social groups in the Gulf of Eilat. When the male and largest female were removed from each of 12 single-male groups, the second-largest female changed sex in 9 groups. This result distinguished between two behavioral hypotheses suggested by previous work and made it tenable that a particular behavioral measure, the profile of behavior-received, that depends on adult females, is critical to the initiation of sex change. This species forms all-female groups as well as bisexual groups. All-female groups can be expected to have some mechanism for the production of a male. The removal of the largest female from each of 8 all-female groups failed to induce sex change in any group. The dominant female in these groups thus does not function in the same way as does the male in bisexual groups, at least in terms of the initiation of sex change. Following the removal of the male from each of 8 bisexual groups containing five or fewer adult females, a female changed sex in only 4 groups. This 50% incidence of sex reversal was lower than the 77–80% incidence in control groups containing more than five adult females. Data suggest that a minimum of four adult females is probably required for the probability of sex change after male removal to equal 75%.     

Broad-host-range IncP-4 plasmid R1162: effects of deletions and insertions on plasmid maintenance and host range

R1162 is an 8.7-kilobase (kb) broad-host-range replicon encoding resistance to streptomycin and sulfa drugs. In vitro deletion of 1.8-kb DNA between coordinates 3.0 and 5.3 kb did not affect plasmid maintenance, but a Tn1 insertion at coordinate 6.3 kb led to a recessive defect in plasmid maintenance. The only cis-acting region necessary for plasmid replication appears to lie between the Tn1 insertion at coordinate 6.3 kb and a second Tn1 insertion at coordinate 6.5 kb. All R1162 sequences between position 6.5 kb and the EcoRI site at coordinate 8.7/0 kb were dispensible for replication in Escherichia coli and Pseudomonas putida. Plasmids carrying insertions in a variety of restriction sites in an R1162::Tn1 derivative were unstable in P. putida but stable in E. coli. Tn5 insertions in R1162 showed a hot spot at coordinate 7.5 kb. A Tn5 insertion at coordinate 8.2 kb appeared to mark the 3' end of the streptomycin phosphotransferase coding sequence. All R1162::Tn5 derivatives showed specific instability in Pseudomonas strains but not in E. coli. The instability could be relieved by internal deletions of Tn5 sequences. In the haloaromatic-degrading Pseudomonas sp. strain B13, introduction of an unstable R1162::Tn5 plasmid led to loss of ability to utilize m-chlorobenzoate as a growth substrate. Our results showed that alteration of plasmid sequence organization in nonessential regions can result in restriction of plasmid host range.     

Altered in vitro phosphorylation of specific proteins accompanies fertilization of Strongylocentrotus purpuratus eggs

Protein phosphorylation in eggs of Strongylocentrotus purpuratus was examined by incubation of egg homogenates with γ[³²P]ATP. Individual phosphorylated proteins were detected by autoradiography after electrophoresis of the disaggregated proteins on SDS-polyacrylamide slab gels. Nearly all of the radioactivity was labile to treatment with pronase, but not to ribonuclease or hydroxylamine, suggesting it to be in the form of protein phosphoesters. The pH dependence for phosphorylation was broad, with cyclic 3′,5′-adenosine monophosphate (cAMP)-dependent phosphorylation optimal at pH 7.7. Phosphorylation of several protein species at pH 7.7 was altered in homogenates of fertilized eggs, when compared to that of unfertilized eggs. These relative increase or decreases in intensity detected by autoradiography were not accompanied by corresponding changes in protein staining of the gels, suggesting that the differences were not due to major shifts in overall protein composition. Most of the alterations in phosphorylation were evident in homogenates made within 5 min after fertilization and were stable until the first cell division. The alterations were also found with homogenates of eggs activated with the divalent ionophore A23187, and some, but not all were present following treatment with ammonia, under conditions that induce a partial metabolic activation of eggs. The results suggest that fertilization promotes alterations in the availability of phosphorylation sites in egg homogenates, or changes in the activity of the egg kinases toward specific protein substrates, that may play a role in the activation of egg metabolism.     

The aromatic amino acid pathway branches at L-arogenate in Euglena gracilis.

The recently characterized amino acid L-arogenate (Zamir et al., J. Am. Chem. Soc. 102:4499-4504, 1980) may be a precursor of either L-phenylalanine or L-tyrosine in nature. Euglena gracilis is the first example of an organism that uses L-arogenate as the sole precursor of both L-tyrosine and L-phenylalanine, thereby creating a pathway in which L-arogenate rather than prephenate becomes the metabolic branch point. E. gracilis ATCC 12796 was cultured in the light under myxotrophic conditions and harvested in late exponential phase before extract preparation for enzymological assays. Arogenate dehydrogenase was dependent upon nicotinamide adenine dinucleotide phosphate for activity. L-Tyrosine inhibited activity effectively with kinetics that were competitive with respect to L-arogenate and noncompetitive with respect to nicotinamide adenine dinucleotide phosphate. The possible inhibition of arogenate dehydratase by L-phenylalanine has not yet been determined. Beyond the latter uncertainty, the overall regulation of aromatic biosynthesis was studied through the characterization of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase and chorismate mutase. 3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase was subject to noncompetitive inhibition by L-tyrosine with respect to either of the two substrates. Chorismate mutase was feedback inhibited with equal effectiveness by either L-tyrosine or L-phenylalanine. L-Tryptophan activated activity of chorismate mutase, a pH-dependent effect in which increased activation was dramatic above pH 7.8 L-Arogenate did not affect activity of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase or of chorismate mutase. Four species of prephenate aminotransferase activity were separated after ion-exchange chromatography. One aminotransferase exhibited a narrow range of substrate specificity, recognizing only the combination of L-glutamate with prephenate, phenylpyruvate, or 4-hydroxyphenylpyruvate. Possible natural relationships between Euglena spp. and fungi previously considered in the literature are discussed in terms of data currently available to define enzymological variation in the shikimate pathway.     

Deriving heart period variability from blood pressure waveforms.

International standards for calculating heart period variability (HPV) from a series of R-wave intervals (R-R) in an electrocardiographic (ECG) recording have been widely accepted. It is possible, and potentially useful in various settings, to use systolic blood pressure waveform intervals to estimate HPV, but the validity of HPV derived from blood pressure (BP) waveforms has not been established. To test the reliability between BP- and ECG-derived HPV indexes, we evaluated data from 234 healthy adults in four studies of HPV reactivity to stress. Study conditions included resting baseline, arithmetic, Stroop test, speech presentation, and orthostatic tilt. Continuous ECG and BP recordings were sampled at a rate of 500 Hz, scored by the same methods, and used to calculate heart rate and time- and frequency-domain measures of HPV. Overall, reliability between the two methods was very high for computing heart rate and HPV indexes. High-frequency HPV indexes were somewhat less reliably computed. In conclusion, in healthy adults, with the use of appropriate methods, BP waveforms can produce reliable indexes of HPV.     

The Cultural Analysis of Kinship: The Legacy of David M. Schneider.; Filiation and Affiliation.

The Cultural Analysis of Kinship: The Legacy of David M. Schneider. Richard Feinberg and Martin Ottenheimer. eds. Champaign: University of Illinois Press, 2001. 235 pp.
Filiation and Affiliation. Harold W. Scheffler. Cambridge: Westview Press, 2001. 202 pp.     

Demographic, reproductive, medical, and environmental factors in relation to gastroschisis.

To identify risk factors for gastroschisis other than drug use in pregnancy, an analysis of data collected in a case-control surveillance program of birth defects (1976-1990) was conducted. Drug use is considered in Werler et al., Teratology, 45:361-367, 1992. Maternal demographic, reproductive, and medical factors, and first trimester environmental exposures, were compared between 76 gastroschisis cases and 2,581 malformed controls. A strong inverse association was found for maternal age: relative to women 30 years or older, relative risks for 25-29, 20-24, and less than 20-year-old women were 1.7, 5.4, and 16, respectively. Multivariate relative risks (and 95% confidence intervals) for alcohol use were as follows: for 1-5 drinks per week, 1.6 (0.7-3.4); for greater than or equal to 6 drinks per week, 2.5 (0.9-6.8); for a maximum of 1-4 drinks at any one time, 0.8 (0.4-1.6); and for a maximum of greater than or equal to 5 drinks, 2.8 (1.2-6.5). With the effect of age taken into account, no associations were identified for cigarette smoking, consumption of caffeinated or decaffeinated coffee, unplanned pregnancy, 12 or less years of education, or a parity of two or more. Other medical and reproductive factors, including weight gain, vaginal bleeding, nausea or vomiting, influenza, "other" infection, and history of spontaneous abortion or elective abortion did not increase the risk.