A 'Southern Cross' method for the analysis of genome organization and the localization of transcription units

A 'Southern Cross' hybridization method is described which permits the rapid restriction mapping of DNA molecules, up to 40 kb in size, for at least ten enzymes in a single operation. The procedure allows the full set of 32P-end-labelled fragments derived from one restriction enzyme digest to intersect and attempt to hybridize to the gel-separated fragments of as many as ten unlabelled digests immobilized on parallel sheets of filter paper. A two-dimensional array of hybridization spots is revealed on each recipient paper, indicating which radioactive and non-radioactive DNA fragments have sequences in common. A restriction map can then be directly and simply deduced from the matrix of hybridization spots in each cross-blot. The method affords advantages over other procedures for obtaining restriction maps in terms of the time required, the number of restriction enzymes that can be mapped, and the potential for eliminating ambiguity. It is also sufficiently sensitive to detect DNA rearrangements and restriction-site polymorphisms in moderately complex genomes. Furthermore, the procedure is applicable to other aspects of the study of genome organization: for example, the exon and intron areas of a segment of cloned genomic DNA can be identified by cross-hybridizing a set of radioactive restriction fragments from the genomic clone against immobilized RNA from a cell type of interest.     

Modernization, stress, and blood pressure: new directions in research.

The relationship between modernization and blood pressure has been formally examined in anthropology for some 3 decades. A prominent hypothesis to account for the increase in blood pressure in more modernized (or economically developed) communities is the stressful nature of cultural and social change. Research has progressed from hypothesizing that culture change is stressful to trying to operationalize theoretical models of what it is about culture change that is stressful and in turn relating those more precise variables to blood pressure variability within and between communities. Here, I selectively review the literature on modernization and blood pressure, especially the research literature that explicitly uses models of the stress process to guide that research. The most interesting results have been obtained when the use of the stress model has been informed by careful ethnographic work. This has enabled researchers to adapt models of the stress process to be culturally appropriate in local populations. In addition, incorporating an explicit model of culture, especially one that is sensitive to intracultural diversity, has led to new hypotheses regarding the modification of the effects of stressors by social and cultural context. I conclude with a discussion of recent innovations in ethnographic methods, specifically the cultural consensus model, and the use of those methods in operationalizing relevant variables in culturally appropriate and sensitive ways. The utility of combining these methods in the study of modernization and blood pressure is illustrated by recent research in Brazil.     

Expression and regulation of a proenkephalin beta-galactosidase fusion gene in the reproductive system of transgenic mice.

A fusion gene containing 3 kilobases of human proenkephalin 5'-flanking sequences and 1 kilobase of human proenkephalin 3'-flanking sequence and the easily visualized histochemical marker, Escherichia coli beta-galactosidase, was used to study the function of cis-regulatory elements within the human proenkephalin gene in transgenic mice. Here data are presented on expression and regulation of this fusion gene in the reproductive system of three independent lines of transgenic mice. Within the male reproductive system, the fusion gene is expressed in the proximal epididymis and in developing germinal cells but not in mature or elongating spermatids. In the female reproductive system, the transgene was expressed at low basal levels, but expression was dramatically stimulated in the ovary and oviduct by hormonal stimulation and pregnancy; additionally, expression was induced at the uteroplacental junction in pregnant mice. Taken together these observations suggest that critical sequences for expression and regulation of the proenkephalin gene within the reproductive system are contained within sequences of the construct.     

SplitsTree: analyzing and visualizing evolutionary data

MOTIVATION: Real evolutionary data often contain a number of different and sometimes conflicting phylogenetic signals, and thus do not always clearly support a unique tree. To address this problem, Bandelt and Dress (Adv. Math., 92, 47-05, 1992) developed the method of split decomposition. For ideal data, this method gives rise to a tree, whereas less ideal data are represented by a tree-like network that may indicate evidence for different and conflicting phylogenies. RESULTS: SplitsTree is an interactive program, for analyzing and visualizing evolutionary data, that implements this approach. It also supports a number of distances transformations, the computation of parsimony splits, spectral analysis and bootstrapping.      

Encyclia altissima Schlechter (Orchidaceae), a resurrected name for the Bahama Flora

The nameEncyclia hodgeana (A. D. Hawkes) Beckner has been incorrectly applied toE. altissima Schlechter in the Bahamas.     

Taxonomy of barkeria (Orchidaceae)

The genusBarkeria (Orchidaceae) consists of four species and eight subspecies (the treatment includes a key) of epiphytic plants endemic to Mexico and Central America.Barkeria is separated from the genusEpidendrum on the structure of the rostellum and column in the flower, plus shape of the pseudobulbs. The authors suggest thatBarkeria is most closely related toCaularthron based on the general shape of the flowers, widely spreading fleshy column wings, and structure of the rostellum.