The delineation of fertility strategies in a tribal population of India: the Koyas of Koraput District,Orissa

Demographic data collected for a tribal population of India, the Koyas of Koraput District, Orissa, were examined in light of 2 models of reproductive behavior associated with the economic value of children: the replacement effect and son survivorship motivation. Both models are united in the concept that infant/child mortality affects subsequent fertility. The database consists of retrospective fertility histories of Koya women who had completed their reproductive period. The total number was 260, with the total offspring numbering 1407. 2 distinct cohorts of women were formed for the purpose of analysis, separated only by the criterion of offspring survival: women who had experienced infant child mortality (129 women with 739 children); and women who completed their reproductive period without suffering offspring loss of this nature (132 women with 668 children). The cohort without child loss had a mean parity of 5.10, lower than the average parity of 5.73 recorded for the cohort whose reproductive histories included at least 1 infant/child death. Age specific marital fertility and birth interval analyses indicated that this differential was because of biological, not behavioral, factors. The age pattern of fertility of females suffering offspring mortality failed to demonstrate a high rate of childbearing in the later age intervals of the reproductive period, a characteristic pattern of couples attempting to "replace" lost offspring. Birth interval analysis pointed to biological "interval effect," whereby infant/child mortality caused a cessation of lactation and hence a shortening of postpartum amenorrhea. Computer simulation further indicated that the higher fertility differential of the cohort experiencing offspring loss still did not result in high son survivorship values. The findings agree with earlier studies indicating that for predemographic transitional populations, economically motivated fertility strategies are ineffectual.     

Molecular characterization of a rotaviruslike virus isolated from striped bass (Morone saxatilis).

The characteristics of a rotaviruslike (SBR) virus isolated from striped bass (Morone saxatilis) were examined following purification of viruses from infected cell cultures. Virions had a double-layered capsid of icosahedral symmetry and a diameter of 75 nm. Purified viruses contained five polypeptides ranging in molecular mass from 130 to 35 kDa. None of the structural proteins were glycosylated. Treatment with EDTA did not remove the outer capsid. By using enzymes and a chaotropic agent, it was shown that VP5 was the most external polypeptide. The genome of SBR virus was composed of 11 segments of double-stranded RNA (dsRNA). The electrophoretic pattern of the dsRNA of SBR virus was different from that of reovirus type 1 (Lang) and rotavirus (SA11) dsRNA. The SBR virus was compared with reovirus type 1 and SA11 virus by RNA-RNA blot hybridization. There was no cross-hybridization between any of the genome segments of the SBR, reovirus type 1, or SA11 viruses. Antigenic comparison of SBR virus and SA11 virus by cross-immunoprecipitation and cross-immunofluorescence tests did not show any relationship. These results suggest that SBR virus could represent a new genus within the family Reoviridae.     

Design of Peptides Using α,β-Dehydro-residues: Synthesis,Crystal Structure and Molecular Conformation of N-Boc-L-Val-ΔPhe–ΔPhe-L-Ala-OCH3

To obtain general rules of peptide design using α,β-dehydro-residues, a sequence with two consecutive ΔPhe-residues, Boc-L -Val-ΔPhe–ΔPhe- L -Ala-OCH₃, was synthesized by azlactone method in solution phase. The peptide was crystallized from its solution in an acetone/water mixture (70:30) in space group P6₁ with a=b=14.912(3) Å, c= 25.548(5) Å, V=4912.0(6) ų. The structure was determined by direct methods and refined by a full matrix least-squares procedure to an R value of 0.079 for 2891 observed [I?3σ(I)] reflections. The backbone torsion angles ?₁=?54(1)°, ψ₁= 129(1)°, ω₁=?177(1)°, ?₂ =57(1)°, ψ₂=15(1)°, ω₂ =?170(1)°, ?₃=80(1)°, ψ₃ =7(2)°, ω₃=?177(1)°, ?₄ =?108(1)° and ψ^T₄=?34 (1)° suggest that the peptide adopts a folded conformation with two overlapping β-turns of types II and III′. These turns are stabilized by two intramolecular hydrogen bonds between the CO of the Boc group and the NH of ΔPhe³ and the CO of Val¹ and the NH of Ala⁴. The torsion angles of ΔPhe² and ΔPhe³ side chains are similar and indicate that the two ΔPhe residues are essentially planar. The folded molecules form head-to- tail intermolecular hydrogen bonds giving rise to continuous helical columns which run parallel to the c-axis. This structure established the formation of two β-turns of types II and III′ respectively for sequences containing two consecutive ΔPhe residues at (i+2) and (i+3) positions with a branched β-carbon residue at one end of the tetrapeptide.     

Action of selected heavy metal ions on the photosystem 2 activity of the cyanobacteriumSpirulina platensis

Addition of different concentrations of heavy metal ions (Hg²⁺, Cu²⁺, Ni²⁺ and Pb²⁺) inhibited the photosystem 2 catalyzed electron transport activity (H₂O→p-benzo-quinone) of the cyanobacteriumSpirulina platensis. Hg²⁺ caused the inhibition in electron transport activity in very low concentrations compared to the other metal ions. Hg²⁺ at this low concentration specifically altered the spectral properties of phycocyanin of the phycobilisomes in the intact cells ofSpirulina, whereas other heavy metal ions were ineffective in this sense.     

Glycinebetaine enhances and stabilizes the evolution of oxygen and the synthesis of ATP by cyanobacterial thylakoid membranes.

Glycinebetaine (betaine), an osmoregulant in halophilic plants, stabilized the evolution of oxygen and the synthesis of ATP by thylakoid membranes from the cyanobacterium Synechocystis PCC6803 when it was present during the preparation and incubation of the thylakoid membranes. Moreover, betaine enhanced the evolution of oxygen and the synthesis of ATP when present during assays. When betaine at 1.0 M was present during the preparation of thylakoid membranes and during the measurement of activity, the rate of evolution of oxygen was equivalent to that of intact cells.     

Effect of directional selection on spontaneous male recombination in Drosophila ananassae.

Artificial selection was carried out for high and low spontaneous male recombination values in D. ananassae for nine generations by using cu b se marker (second chromosome) and wild stocks which were free from heterozygous chromosome inversions. The mean crossing-over frequency of nine generations was 2.22, 0.70 and 1.20% in high, low and control lines respectively. The values of regression coefficient and realized heritability also indicated that male recombination was affected by selection. However, response to selection was more pronounced in high line as compared to low line. This provides evidence that spontaneous male crossing-over in D. ananassae is under polygenic control.     

Analysis of dark-relaxation kinetics of variable fluorescence in intact leaves

The dark-relaxation kinetics of variable fluorescence, F_v, in intact green leaves of Pisum stativum L. and Dolichos lablab L. were analyzed using modulated fluorometers. Fast (t_1/2 = 1 s) and slow (t_1/2 = 7–8 s) phases in f_v dark-decay kinetics were observed; the rate and the relative contribution of each phase in total relaxation depended upon the fluence rate of the actinic light and the point in the induction curve at which the actinic light was switched off. The rate of the slow phase was accelerated markedly by illumination with far-red light; the slow phase was abolished by methyl viologen. The halftime of the fast phase of F_v dark decay decreased from 250 ms in dark-adapted leaves to 12–15 ms upon adaptation to red light which is absorbed by PSII. The analysis of the effect of far-red light, which is absorbed mainly by PSI, on F_v dark decay indicates that the slow phase develops when a fraction of Q_A ^– (the primary stable electron acceptor of PSII) cannot transfer electrons to PSI because of limitation on the availability of P700⁺ (the primary electron donor of PSI). After prolonged illumination of dark-adapted leaves in red (PSII-absorbed) light, a transient. F_v rise appears which is prevented by far-red (PSI-absorbed) light. This transient f_v rise reflects the accumulation of Q_A ^– in the dark. The observation of this transient F_v rise even in the presence of the uncoupler carbonylcyanide m-chlorophenyl hydrazone (CCCP) indicates that a mechanism other than ATP-driven back-transfer of electrons to QA may be responsible for the phenomenon. It is suggested that the fast phase in F_v dark-decay kinetics represents the reoxidation of Q_A ^– by the electron-transport chain to PSI, whereas the slow phase is likely to be related to the interaction of Q_A ^– with the donor side of PSII.Abbreviations CCCP carbonylcyanide m-chlorophenylhydrazone - F_O initial fluorescence level - F_v variable fluorescence - P700 primary electron donor of PSI - PSI, II photosystem I, II - Q_A (Q_A ^–) Q_B (Q_B ^–) primary and secondary stable electron acceptor of PSII in oxidized (reduced) state Supported by grant B6.1/88 DST, Govt. of India.     

Effect of methallibure (ICI 33,828) on the pituitary-gonad and the pituitary-thyroid axes of the Indian garden lizard,Calotes versicolor (Daudin)

Summary The effect of methallibure (ICI 33,828) on the pituitary-gonad and the pituitary-thyroid axes of the Indian garden lizard, Calotes versicolor was studied. Following administration of methallibure B₂ (FSH) and B₃ (ICSH) cells of the pars distalis exhibited significant alterations with concomitant changes in the seminiferous tubules, and in the interstitial cells and epididymis respectively. B₁ (TSH) cells exhibited conspicuous hypertrophy and degranulation which was reflected in dramatic changes in thyroid morphology. The caudally localized acidophilic A₁ (PRL) cells also showed hypertrophy, hyperplasia and intense granulation. The rostrally located A₂ (STH) acidophils and the B₄ (ACTH) cells were unaffected by the treatment. The possible mode of action of this drug is discussed in the light of available literature.Supported by a grant from the University Grants Commission of India. The generous supply of methallibure by Dr. A.L. Walpole of the Imperial Chemical Industries Limited, England, through Professor C.J. Dominic, Banaras Hindu University, is gratefully acknowledged