Inhibition and labelling of isolated reaction centers from Rhodobacter sphaeroides by dicyclohexylcarbodiimide

The effect of dicyclohexylcarbodiimide (DCCD) on electron transfer in the acceptor quinone complex of reaction centers (RC) from Rhodobacter sphaeroides is reported. DCCD covalently labelled the RC over a wide concentration range. At low concentrations (<10 M) the binding was specific for the L subunit. At relatively high concentrations (>100 M) DCCD accelerated the rate of charge recombination of the P⁺Q_B ^- state, consistent with a decrease in the equilibrium constant between Q_A ^-Q_B and Q_AQ_B ^-. At similar concentrations, in the presence of cytochrome c as exogenous donor, turnover of the RC was inhibited such that only three cytochromes were oxidized in a train of flashes. Both these inhibitory effects were fully reversed by dialysis, indicating that stable covalent binding was not involved. Possible mechanisms of action are discussed in terms of the putative role of specific residues in proton transfer and protonation and release of quinol from the RC.     

Ecology of gorillas and its relation to female transfer in mountain gorillas

Understanding the principles that underly primate social evolution depends on integrated analysis of data on behavioral ecology, demography, life history tactics, and social organization. In this paper, data on the behavioral ecology of gorillas are reviewed and comparisons made among the three subspecies. Gorillas are selective feeders; and, their patterns of food choice are consistent with models of feeding by large generalist herbivores. They rely heavily on terrestrial herbaceous vegetation, which provides an abundant supply of densely distributed food. Availability of this food varies little in space and time; and, gorilla foraging activity can maintain its productivity. The level of frugivory and the extent of seasonal variation in diet and habitat use vary among and within populations. Low variability in food distribution patterns makes cooperative defense of foraging areas not worthwhile; but, it also means that ecological costs associated with gregariousness are low. However, demographic and life history data on mountain gorillas show that these costs may be sufficient to reduce female reproductive success as group size increases. Advantages to being with high quality males apparently can outweigh these costs. The implications of these data for the evolution of the mountain gorilla social system, and the possible roles of male protection, predation, and female/female competition in this regard, are discussed.     

A stuttering model for paramyxovirus P mRNA editing.

Paramyxovirus P genes are transcribed into two mRNAs which differ from each other by either one (measles and Sendai virus) or two (SV5 and mumps virus) G insertions, and which code for either the P or V proteins. The G insertions always occur within a short run of Gs, and a stuttering mechanism for the insertions has been suggested in which the viral polymerase reiteratively copies a template C residue during mRNA synthesis. Support for this mechanism was obtained by varying the reaction conditions during Sendai virus mRNA synthesis in vitro. A stuttering model is proposed which accounts for how the ratio of inserted to uninserted mRNAs is controlled, and why some paramyxoviruses insert one G and others two Gs when insertions occur.     

Distinct sequence elements control the specificity of G protein activation by muscarinic acetylcholine receptor subtypes.

Relatively little is understood concerning the mechanisms by which subtypes of receptors, G proteins and effector enzymes interact to transduce specific signals. Through expression of normal, hybrid and deletion mutant receptors in Xenopus oocytes, we determined the G protein coupling characteristics of the functionally distinct m2 and m3 muscarinic acetylcholine receptor (mAChR) subtypes and identified the critical receptor sequences responsible for G protein specificity. Activation of a pertussis toxin insensitive G protein pathway, leading to a rapid and transient release of intracellular Ca2+ characteristic of the m3 receptor, could be specified by the transfer of as few as nine amino acids from the m3 to the m2 receptor. In a reciprocal manner, transfer of no more than 21 residues from the m2 to the m3 receptor was sufficient to specify activation of a pertussis toxin sensitive G protein coupled to a slow and oscillatory Ca2+ release pathway typical of the m2 subtype. Notably, these critical residues occur within the same region of the third cytoplasmic domain of functionally distinct mAChR subtypes.     

Giving between generations in American families

This paper documents the types and amounts of aid exchanged between adults and their non-coresidential parents. Data for the study are drawn from a representative national sample survey of Americans age 19 and older conducted in 1987–1988. Exchanges of monetary and material resources, childcare, household assistance, and companionship and advice are considered. Patterns of intergenerational exchange are found to differ by gender, family structure, age, ethnicity, and socioeconomic situation. Differences in exchange between males and females and between whites and Mexican-Americans are related to other life-course characteristics, and to the availability and proximity of kin. Blacks and persons living in poverty are shown to be less involved than other groups in intergenerational exchanges. Finally, patterns of prior assistance and the available needs and resources of the respondents and their parents are found to influence current patterns of exchange. Support for this research was provided by NICHD Grant No. 1 R01 HD26070-01, “Intergenerational Exchanges in Families with Children,” Dennis P. Hogan, Principal Investigator. Funds for the computer analysis were provided by the Pennsylvania State University Intercollege Research Programs. David Eggebeen is an Assistant Professor of Human Development in the Department of Human Development and Family Studies and a research associate at the Population Issues Research Center at Pennsylvania State University. He trained in sociology and demography at the University of North Carolina. His current research interests, besides those related to intergenerational relations, are the recent changes in the demographic structure of childhood in America and their implications for children’s social and economic well-being. Dennis P. Hogan is a professor of sociology and the director of the Population Issues Research Center at Pennsylvania State University. His current research interests, besides those related to intergenerational relations, are in the interrelation of social structures and the demographic life course. He is coauthor with David I. Kertzer ofFamily, Political Economy, and Demographic Change: The Transformation of Life in Casalecchio, Italy, 1861–1921, University of Wisconsin Press, 1989.     

Enhancer sequences located 3' of the mouse immunoglobulin lambda locus specify high-level expression of an immunoglobulin lambda gene in B cells of transgenic mice

In contrast to the mouse immunoglobulin heavy chain and kappa light chain genes, very little is known about the regulation of expression of the immunoglobulin lambda light chain locus. To identify elements responsible for lambda gene regulation we mapped DNaseI hypersensitive sites associated with a functionally rearranged lambda 1 gene in nuclei from the myeloma cell line J558L. Tissue-specific hypersensitive sites were identified 2.3 to 2.5 kb upstream of the CAP site of both the lambda 1 gene and the unrearranged variable (V) lambda 2 gene segments. DNA sequences flanking the lambda 1 gene were isolated and tested for their influence on expression of the lambda 1 gene after transfection into myeloma cells and after injection into fertilized mouse eggs. Two enhancer elements were identified downstream of the lambda 1 gene. A proximal element (located 4 to 10 kb 3' of the gene) enhanced expression of a lambda 1 gene in stable myeloma cell transfectants but had no effect on the expression of a heterologous reporter gene in transient assays. A second, distal element, located approximately 30 kb 3' of the gene, enhanced heterologous expression in J558L cells expressing a lambda gene but not in a non-lambda myeloma cell line (SP2/0-Ag14). Co-injection of cosmids containing the lambda 1 gene and both the proximal and distal downstream elements into fertilized mouse eggs resulted in high-level expression of the lambda 1 transgene in B cells of transgenic mice. The identification of these lambda regulatory elements, in addition to contributing to an understanding of lambda gene regulation per se, will facilitate the study of the regulation of differential expression of kappa and lambda light chain genes in the immune system.     

Subjective experiences associated with thermal biofeedback treatment of hypertension

Reports of subjective experiences of 73 hypertensive patients who were treated with thermal biofeedback for hand warming were obtained over 16 treatment sessions. Most of the differential responding in subjective report occurred in the first 5 sessions. Differences in reports of throbbing were associated with medication status during treatment (presence of sympatholytic antihypertensive agent). From 4 to 9% of patients report negative subjective experiences at any one session. When short-term clinical successes (either elimination of medication or reduction of BP) were compared with short-term failures, it was found that successes reported more warmth, more likelihood of falling asleep, and more dreamlike experiences. The latter were more likely to occur suddenly for the successes. Correlational analyses revealed consistent positive associations between reports of warmth and relaxation with highest temperature achieved in the session and consistent negative associations between experiencing physical sensations and degree of temperature change within the session.This research was supported in part by grants from NHLBI, HL-27622 and HL-31189.     

In vitro culture of tissue from the tunicateStyela clava

Summary Pharyngeal explants and circulatory hemocytes from the tunicateStyela clava were cultured in a medium containing tunicate plasma, artificial seawater, RPMI 1640, and antibiotics. Pharnngeal tissue remained viable and proliferated for up to 72 d in vitro. Proliferative activity maintained the pool of hemocytes within explants and facilitated the migration of pharyngeal hemocytes from explants into culture supernatants. The diversity of morphologically distinct cell types within the hemocyte pool of pharyngeal cultures indicated that cell division was followed by regulated differentiation. In contrast to pharyngeal cultures, suspensions of circulatory hemocytes did not survive for prolonged periods in vitro. Proliferative activity could not be detected in circulatory hemocyte cultures. These results are discussed in terms of the differentiation state of hemocytes and the efficacy of culture conditions. This study was supported by the National Science Foundation, Washington, DC (grant DCB 85 19848) and by BRSG funds from UCLA Schools of Medicine and Dentistry. Flow cytometric facilities were sponsored in part by a Johnson Cancer Center Core Grant (CA 16042). David A. Raftos is a Fulbright Postdoctoral Fellow and recipient of a Frederik B. Bang Scholarship in Marine Invertebrate Immunology administered by the American Association of Immunologist. Dan L. Stillman was supported by an REU supplement from the National Science Foundation.     

SPLICE, a computer program for automated extraction of information from GenBank sequence entries

SPLICE, a software tool for the extraction of sequences fromfiles in GenBank tape format, has been developed. The programcan analyze the features table in this format and use any ofthe information provided to write the corresponding sequencesinto a standard sequence file format suitable for use with sequenceanalysis programs. Sequences that are present as several subsequentfragments in a single GenBank file, such as those encoding apeptide, can be spliced together by the program. Further, sequencesthat are present in more than one Genbank file, such as an exonwhich spans several different files, can also be spliced intoone sequence. SPLICE runs under the MS/DOS and Unix operatingsystems, can be called as a sub-process by other programs andcan process batches of files. Received on December 26, 1989; accepted on May 30, 1990