Genetic and cultural pools: Some suggestions for a unified theory of biocultural evolution

By introducing the concept of the natural selection of individual organisms, Darwin was able to cut through the mystification surrounding theological discussions of the origin of species. By placing the concept of an individual struggle for satisfaction in an analogous conceptual framework, a similar feat may be performed with regard to the mystification and reification surrounding much of contemporary social science. The proposed theory states that individuals are the generating force behind the origin, spread, and transformations of sociocultural complexes and that all sociocultural phenomena are explicable in terms of the differential replication of ideas by individuals as this is conditioned by selective pressures generated by particular material conditions of life. The theory is used to illuminate certain key issues in evolution, such as adaptation, group selection, and free will This is a revised version of a paper originally presented at the Seventieth Annual Meetings of the American Anthropological Association in New York, November 19, 1971.     

Asymmetric cell division: a new way to divide unequally

It has long been known that cells can divide unequally by shifting the mitotic spindle to one side. Two recent reports identify an alternative way to generate daughter cells of different sizes.     

Identification of new genes in a cell envelope-cell division gene cluster of Escherichia coli: cell division gene ftsQ.

We report the identification, cloning, and mapping of a new cell division gene, ftsQ. This gene formed part of a cluster of three division genes (in the order ftsQ ftsA ftsZ) which itself formed part of a larger cluster of at least 10 genes, all of which were involved in some step in cell division, cell envelope synthesis, or both. The ftsQAZ group was transcribed from at least two independent promoters.     

Some suggestions for future cladoceran research

The topics dealt with at the Cladoceran Symposium showed a largediversity. A high diversity is what characterises the world westudy, consisting of many different habitats and a rich speciesset. This easily leads to anecdotal research which then preventsthe building of a consistent and sophisticated body of knowledge.The contribution of cladoceran research to general ecologicaltheory is limited as a look in textbooks reveals. Therefore,choices have to be made for future research and a few suggestionsto this extent are shortly mentioned in this essay in consequenceof the Symposium on Cladocera held in Postojna (Slovenia), August1996.     

Targeting the Wolbachia cell division protein FtsZ as a new approach for antifilarial therapy

The use of antibiotics targeting the obligate bacterial endosymbiont Wolbachia of filarial parasites has been validated as an approach for controlling filarial infection in animals and humans. Availability of genomic sequences for the Wolbachia (wBm) present in the human filarial parasite Brugia malayi has enabled genome-wide searching for new potential drug targets. In the present study, we investigated the cell division machinery of wBm and determined that it possesses the essential cell division gene ftsZ which was expressed in all developmental stages of B. malayi examined. FtsZ is a GTPase thereby making the protein an attractive Wolbachia drug target. We described the molecular characterization and catalytic properties of Wolbachia FtsZ. We also demonstrated that the GTPase activity was inhibited by the natural product, berberine, and small molecule inhibitors identified from a high-throughput screen. Furthermore, berberine was also effective in reducing motility and reproduction in B. malayi parasites in vitro. Our results should facilitate the discovery of selective inhibitors of FtsZ as a novel anti-symbiotic approach for controlling filarial infection.

Note

The nucleotide sequences reported in this paper are available in GenBank™ Data Bank under the accession number wAlB-FtsZ ({"type":"entrez-nucleotide","attrs":{"text":"JN616286","term_id":"346720767","term_text":"JN616286"}}JN616286).     

Some suggestions for a possible approach to a mathematical biophysics of mitosis

A tentative suggestion is made to interpret the phenomenon of mitosis as being due to coiling and uncoiling of long chain molecules, which are assumed to constitute the spindle. A possible quantitative approach is briefly outlined.     

Cell division ring, a new cell division protein and vertical inheritance of a bacterial organelle in anammox planctomycetes

Anammox bacteria are members of the phylum Planctomycetes that oxidize ammonium anaerobically and produce a significant part of the atmosphere's dinitrogen gas. They contain a unique bacterial organelle, the anammoxosome, which is the locus of anammox catabolism. While studying anammox cell and anammoxosome division with transmission electron microscopy including electron tomography, we observed a cell division ring in the outermost compartment of dividing anammox cells. In most Bacteria, GTP hydrolysis drives the tubulin-analogue FtsZ to assemble into a ring-like structure at the cell division site where it functions as a scaffold for the molecular machinery that performs cell division. However, the genome of the anammox bacterium ' Candidatus Kuenenia stuttgartiensis' does not encode ftsZ . Genomic analysis of open reading frames with potential GTPase activity indicated a possible novel cell division ring gene: kustd1438, which was unrelated to ftsZ . Immunogold localization specifically localized kustd1438 to the cell division ring. Genomic analyses of other members of the phyla Planctomycetes and Chlamydiae revealed no putative functional homologues of kustd1438, suggesting that it is specific to anammox bacteria. Electron tomography also revealed that the bacterial organelle was elongated along with the rest of the cell and divided equally among daughter cells during the cell division process.     

Some remarks on the movement of chromosomes during cell division

The possibility of drawing conclusions about the nature of the forces acting upon the chromosomes during division from observation of the rates of their movement in anaphase is pointed out. Some available data are discussed, and shown to agree quantitatively with the assumption that during anaphase the chromosomes are pulled apart by contracting elastic fibers.     

A new cell division operon in Escherichia coli

Summary At 76 min on theE. coli genetic map there is a cluster of genes affecting essential cellular functions, including the heat shock response and cell division. A combination ofin-vivo andin-vitro genetic analysis of cell division mutants suggests that the cell division genefts E is the second gene in a 3 gene operon. A cold-sensitive mutant, defective in the third gene, is also unable to divide at the restrictive temperature, and we designate this new cell division genefts X. Another cell division gene,fts S, is very close to, but distinct from, the 3 genes of the operon. Thefts E product is a 24.5 Kd polypeptide which shows strong homology with a small group of proteins involved in transport. Both thefts E product and the protein coded by the first gene (fts Y) in the operon have a sequence motif found in a wide range of heterogeneous proteins, including the Ras proteins of yeast. This common domain is indicative of a nucleotide-binding site.     

Genetic requirements for cell division in a genomically minimal cell

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DipM,a new factor required for peptidoglycan remodelling during cell division in Caulobacter crescentus

In bacteria, cytokinesis is dependent on lytic enzymes that facilitate remodelling of the cell wall during constriction. In this work, we identify a thus far uncharacterized periplasmic protein, DipM, that is required for cell division and polarity in Caulobacter crescentus. DipM is composed of four peptidoglycan binding (LysM) domains and a C‐terminal lysostaphin‐like (LytM) peptidase domain. It binds to isolated murein sacculi in vitro, and is recruited to the site of constriction through interaction with the cell division protein FtsN. Mutational analyses showed that the LysM domains are necessary and sufficient for localization of DipM, while its peptidase domain is essential for function. Consistent with a role in cell wall hydrolysis, DipM was found to interact with purified murein sacculi in vitro and to induce cell lysis upon overproduction. Its inactivation causes severe defects in outer membrane invagination, resulting in a significant delay between cytoplasmic compartmentalization and final separation of the daughter cells. Overall, these findings indicate that DipM is a periplasmic component of the C. crescentus divisome that facilitates remodelling of the peptidoglycan layer and, thus, coordinated constriction of the cell envelope during the division process.     

Some additional suggestions for an intervertebral disc prosthesis

The paper, which refers to previous original papers on the subject, gives suggestions indicating four intervertebral disc prostheses, one utilizing bone cement for fixation to the bony substance of the motion segment. In the paper a modification of this inter-vertebral disc prosthesis offers a possibility for fixation of the prosthesis by osteointegration.