Induction of murine lymphokine-activated killer cells by recombinant IL-7

The data demonstrate that IL-7, a cytokine that was originally identified, purified, and cloned based upon its ability to support the growth of pre-B cells in vitro, also induces proliferation and promotes the generation of lymphokine-activated killer (LAK) cell activity in populations of resting peripheral lymphoid cells. Although the kinetics of LAK induction by IL-7 (which peaked at days 6 to 8 of culture) was slower than that detected in cultures containing IL-2 (which peaked at day 4), IL-7 was significantly more effective at maintaining cytotoxic activity over longer periods of time, and greater viable cell recoveries, than was IL-2. A wide range of murine tumor target cells were found to be lysed in an MHC-unrestricted fashion by IL-7 induced LAK, but syngeneic Con A-induced lymphoblasts were not; nor were target cells from the human tumors K562 or Daudi lysed by IL-7 LAK. IL-7 LAK were induced in populations of lymphoid cells obtained from secondary lymphoid tissues (peripheral lymph nodes and spleen), but not from primary lymphoid tissues (thymus and bone marrow). LAK induced by IL-7 from unfractionated populations of lymphoid cells were completely eliminated by treatment with anti-CD8 or anti-Thy-1+C, and unaffected by treatment with anti-CD4, anti-asialo GM1 or anti-NK1.1+C. Interestingly, although no detectable CD4+ effector cells could be detected in populations of LAK generated from unfractionated populations of lymphoid cells stimulated by IL-7, they were found to be generated from populations of lymphoid cells from which CD8+ cells had been eliminated before being cultured in medium containing IL-7. These data suggest that CD4+ T cells do not normally give rise to IL-7-induced LAK unless they are first separated from CD8+ T cells. LAK induced by IL-7 appear to be distinct from LAK activity induced by IL-2 in that there is no detectable involvement of NK-like effector cells at either the precursor or effector cell stages.     

Linkage of a variant or attenuated form of adenomatous polyposis coli to the adenomatous polyposis coli (APC) locus.

Adenomatous polyps are an intermediate in the pathway to colon carcinoma. An inherited disorder, familial adenomatous polyposis coli (APC), is characterized by hundreds to thousands of adenomatous polyps. A previously reported family had colon cancer associated with a low average but highly heterogenous number of colonic polyps, this phenotype mapped to the APC locus on 5q. Four new families have been ascertained in which the phenotypic pattern was different from classical polyposis but similar to that of the "prototype" kindred reported earlier. By multilocus linkage analysis, the gene responsible for the disease phenotype was mapped, with a high level of confidence, to the APC locus in two of the four families with the attenuated or variant form of polyposis (AAPC); the results for the two remaining kindreds were inconclusive. A combined maximum LOD score of approximately 7.6 at a recombination fraction of 0 was obtained when the results were summed over the four pedigrees with markers closest to the APC locus. The establishment of genetic linkage in such families may point to the APC locus as having a more significant role in inherited predispositions to colorectal cancer than was previously thought.     

A POPULATION MEMETICS APPROACH TO CULTURAL EVOLUTION IN CHAFFINCH SONG: DIFFERENTIATION AMONG POPULATIONS

We investigated cultural evolution in populations of common chaffinches (Fringilla coelebs) in the Atlantic islands (Azores, Madeira, and Canaries) and neighboring continental regions (Morocco and Iberia) by employing a population-memetic approach. To quantify differentiation, we used the concept of a song meme, defined as a single syllable or a series of linked syllables capable of being transmitted. The levels of cultural differentiation are higher among the Canaries populations than among the Azorean ones, even though the islands are on average closer to each other geographically. This is likely the result of reduced levels of migration, lower population sizes, and bottlenecks (possibly during the colonization of these populations) in the Canaries; all these factors produce a smaller effective population size and therefore accentuate the effects of differentiation by random drift. Significant levels of among-population differentiation in the Azores, in spite of substantial levels of migration, attest to the differentiating effects of high mutation rates of memes, which allow the accumulation of new mutants in different populations before migration can disperse them throughout the entire region.     

THE DISTRIBUTION OF LIFE-HISTORY VARIATION IN THE DAPHNIA PULEX COMPLEX

In the midwestern United States the Daphnia pulex complex consists of a mosaic of sexual and asexual populations, providing a useful model system for studying the evolutionary forces underlying the maintenance of sex. One asexual and two sexual populations were surveyed for genetic variation for isozymes, mitochondrial DNA, and life-history characters. While the sexual populations exhibited substantial levels of genetic variance for fitness characters, no variation was detected in the asexual population at any level. However, a parallel survey among asexual clones derived from other ponds revealed large amounts of quantitative variation among clones, even among those with the same molecular profile. As a group, the asexuals are more variable for life histories than are the sexual populations. The molecular data indicate a relatively recent origin for the extant asexual D. pulex. The polyphyletic origin of these clones, combined with their microevolutionary potential, provides an explanation for their broad geographic distribution. The distribution of sex in the complex cannot be explained with the standard models that assume an invariant asexual population in reproductive isolation from the parental species. Although the frequency of asexuality may be driven by the spread of a sex-limited meiosis suppressor through sexual populations, the complete displacement of sexuality may be prevented by ecological distinctions between the two classes of individuals. On average, the asexuals are larger but produce smaller clutches than the sexuals.     

Recombinant β-glucanase production and plasmid stability of Bacillus subtilis in cyclic fed batch culture

Recombinant -glucanase production and plasmid stability were higher in cyclic fed batch culture than in batch and chemostat culture. Plasmid stability was maintained indefinitely in cyclic fed batch cultures of Bacillus subtilis when subjected to cycle periods of 2 or 4 hours. Cycle periods greater than 6 hours resulted in loss of the plasmid. In batch and chemostat cultures plasmid loss was rapid. -1,3-glucanase productivity was highest in cyclic fed batch culture.     

Seasonal variation of nitrification along a salinity gradient in an urban estuary

A review on salinity adaptation of marine molluscsbased on mainly Russian scientific literature ispresented. The existence of two relativelyindependent systems of adaptation to extreme(resistance level) and moderate (tolerance level)changes of environmental salinity was shown. Theresistance of molluscs is based mainly on an impededwater-salt exchange with the external medium due tomantle cavity hermetization. The tolerance ofmolluscs is determined by cellular mechanisms ofadaptation. Reversible changes of protein and RNAsynthesis, alteration of the pattern of multiplemolecular forms of different enzymes, and theregulation of ionic content and cell volume wereshown to be of importance for the above mentionedmechanisms. The efficiency of resistance andtolerance adaptations to salinity changes may varyin different species and in different colourphenotypes of the same species (intrapopulationalpolymorphism). Parasites (trematodes) may suppressthe resistance of the mollusc-host to extremesalinity changes without effecting the host'scapacity for adaptive changes in salinitytolerance.     

Irgasan-induced pigmentation in Serratia marcescens and Pseudomonas aeruginosa.

Two irgasan-resistant micro-organisms (P. aeruginosa and S. marcescens) were used to study the effects of various antibiotic and chemotherapeutic agents on pigment production. These agents included streptomycin, thallium acetate, polymyxin B, hexachlorophene, irgasan, prodigiosin and DMSO (dimethyl sulphoxide). Only irgasan, compared to other drugs and membrane-active agents showed the unique property of inducing pigmentation in both P. aeruginosa and S. marcescens, i.e. prodigiosin in S. marcescens and pyocyanin in P. aeruginosa.