A CYTOCHEMICAL STUDY OF CYTOPLASMIC BASIC PROTEINS IN THE ASCIDIAN OOCYTE

The cytoplasm of young oocytes of the ascidians contains high concentrations of proteins which are stainable with alkaline fast green at pH 8.1 and above. These proteins cannot be stained even with acid dyes at low pH unless RNA is removed. Deamination and formalin blockage of amino groups is incapable of destroying the net positive charge on these protein molecules in the presence of RNA, but these treatments destroy the charge if RNA is removed. It is therefore concluded that basic proteins and RNA exist as a nucleoprotein complex in the ribosomes of these young oocytes. The detectable RNA of the mature oocytes and unfertilized eggs shows no evidence of being associated with basic proteins.     

The efficacy of biobehavioral and compliance interventions in the adjunctive treatment of mild pregnancy-induced hypertension

This investigation assessed the efficacy of a biobehavioral intervention in the adjunctive treatment of mild pregnancy-induced hypertension (PIH), a potentially serious complication of pregnancy in which normotensive women develop hypertension, proteinuria, and edema of unknown etiology late in gestation. Forty-five women with symptoms of PIH were randomly assigned to one of three treatment conditions: bed rest alone (the most common obstetrical treatment), bed rest with individualized compliance enhancement training, or a four-session biobehavioral treatment consisting of bed rest, compliance enhancement training, and individualized thermal biofeedback-assisted relaxation training. Results indicated that while blood pressure for the bed rest and compliance enhancement groups continued to rise and pose an increasing health risk to maternal and fetal well-being, subjects in the biobehavioral group maintained their blood pressure at a significantly lower, and presumably safer, level. The biobehavioral treatment is hypothesized to affect blood pressure levels in subjects with mild PIH through the mediation of the sympathetic nervous system, decreasing peripheral vascular resistance and cardiac output. The results of this investigation suggest that the biobehavioral intervention may be an effective adjunct to bed rest in the treatment of mild PIH remote from term.     

Ectonucleotidase Activities Associated with the Olfactory Organ of the Spiny Lobster

The olfactory system of the Florida spiny lobster, Panulirus argus, has olfactory receptors that are excited by the purine nucleotides AMP, ADP, and ATP. These receptors reside on chemosensory neurons that are contained within aesthetasc sensilla on the lateral filaments of the antennules. Also associated with the lobster's olfactory system are ectonucleotidase activities that dephosphorylate excitatory nucleotides, resulting in the production of the nonstimulatory nucleoside adenosine. Our studies of the 5'-ectonucleotidase, ecto-ADPase, and ecto-ATPase activities of this olfactory system showed that each activity was characterized by Michaelis-Menten kinetics; Michaelis constants ranged from 6.9 to 33.5 microM, and maximum velocities ranged from 2.5 to 28.8 fmol/sensillum/s. Evidence that AMP dephosphorylation may serve as an inactivation process was shown by the close correlation between the kinetics of 5'-ectonucleotidase activity and the periodicity of olfactory sampling. Decreased magnesium ion concentration or increased calcium ion concentration resulted in increased ecto-ATPase activity; this activity was insensitive to vanadate ion. Ectonucleotidase activities may have multiple effects on the detection of exogenous nucleotides by a chemosensory system. These effects can be either direct, such as the conversion of an odorant to an inactive compound, or indirect, such as the conversion of an odorant to another compound that can activate or inhibit either receptors or enzymes associated with the system.     

Art, Science, or Politics? The Crisis in Hunter-Gatherer Studies

In the complex history of hunter-gatherer studies, several overlapping and at times antagonistic discourses can be discerned. However, one critique has emerged that would render all hunter-gatherer discourses irrelevant and do away with the concept altogether. The paper explores the poststructuralist roots of this "revisionism" and then argues why the concept of hunter-gatherer continues to be politically relevant and empirically valid. However, if they are to fulfill their promise of illuminating an increasingly fragmented and alienating modernity, hunter-gatherer studies will have to become more attuned to issues of politics, history, context, and reflexivity.     

Mechanisms of Injury-Induced Calcium Entry into Peripheral Nerve Myelinated Axons: Role of Reverse Sodium-Calcium Exchange

Abstract: To investigate the route of axonal Ca²⁺ entry during anoxia, electron probe x-ray microanalysis was used to measure elemental composition of anoxic tibial nerve myelinated axons after in vitro experimental procedures that modify transaxolemmal Na⁺ and Ca²⁺ movements. Perfusion of nerve segments with zero-Na⁺/Li⁺-substituted medium and Na⁺ channel blockade by tetrodotoxin (1 µM) prevented anoxia-induced increases in Na and Ca concentrations of axoplasm and mitochondria. Incubation with a zero-Ca²⁺/EGTA perfusate impeded axonal and mitochondrial Ca accumulation during anoxia but did not affect characteristic Na and K responses. Inhibition of Na⁺-Ca²⁺ exchange with bepridil (50 µM) reduced significantly the Ca content of anoxic axons although mitochondrial Ca remained at anoxic levels. Nifedipine (10 µM), an L-type Ca²⁺ channel blocker, did not alter anoxia-induced changes in axonal Na, Ca, and K. Exposure of normoxic control nerves to tetrodotoxin, bepridil, or nifedipine did not affect axonal elemental composition, whereas both zero-Ca²⁺ and zero-Na⁺ solutions altered normal elemental content characteristically and significantly. The findings of this study suggest that during anoxia, Na⁺ enters axons via voltage-gated Na⁺ channels and that subsequent increases in axoplasmic Na⁺ are coupled functionally to extraaxonal Ca²⁺ import. Intracellular Na⁺-dependent, extraaxonal Ca²⁺ entry is consistent with reverse operation of the axolemmal Na⁺-Ca²⁺ exchanger, and we suggest that this mode of Ca²⁺ influx plays a general role in peripheral nerve axon injury.     

Non-reciprocal cross-incompatibility in Trichogramma deion

In non-reciprocal cross-incompatibility (NRCI), the crossing of a female of a strain A with a male of a strain B results in hybrid offspring, whereas the reciprocal cross produces few or no hybrids. Only females are of hybrid origin in Hymenoptera because they arise from fertilized eggs; males arise from unfertilized (haploid) eggs. Crosses between many strains of Trichogramma deion showed some degree of NRCI. Crosses between a T. deion culture collected in Seven Pines, California (SVP) with one from Marysville, California (MRY) showed an extreme form of NRCI in which practically no female offspring was produced when MRY females were crossed with SVP males. The reciprocal cross produced a close to normal proportion of female and male offspring. Detailed studied of this cross indicated that 1) the female offspring produced in the compatible interstrain cross were not the result of parthenogenesis but were true hybrids, 2) the incompatible interstrain cross did not produce female offspring because fertilized eggs died during development, 3) the death of these eggs could not be prevented by either antibiotic or temperature treatment, 4) cytoplasmically inherited factors causing NRCI could be discounted because backcrossed females with the genome of MRY and the cytoplasm of SVP, exhibit the NRCI relationship characteristic of their genome. Therefore the NRCI between these strains appears to be caused by a modification coded for by the nuclear genes of MRY that results in incompatibility when SVP sperm fertilizes MRY eggs. In addition the level of incompatibility in crosses between the SVP females and MRY males is temperature sensitive, the higher the rearing temperature the lower the level of compatibility.     

Genomic complexity and plasticity of Burkholderia cepacia

Abstract Burkholderia cepacia has attracted attention because of its extraordinary degradative abilities and its potential as a pathogen for plants and for humans. This bacterium was formerly considered to belong to the genus Pseudomonas in the γ-subclass of the Proteobacteria , but recently has been assigned to the β-subclass based on rrn gene sequence analyses and other key phenotypic characteristics. The B. cepacia genome is comprised of multiple chromosomes and is rich in insertion sequences. These two features may have played a key role in the evolution of novel degradative functions and the unusual adaptability of this bacterium.