Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park,Rwanda

Almost all primates experience seasonal fluctuations in the availability of key food sources. However, the degree to which this fluctuation impacts foraging behavior varies considerably. Eastern chimpanzees (Pan troglodytes schweinfurthii) in Nyungwe National Park, Rwanda, live in a montane forest environment characterized by lower primary productivity and resource diversity than low‐elevation forests. Little is known about chimpanzee feeding ecology in montane forests, and research to date predominantly relies on indirect methods such as fecal analyses. This study is the first to use mostly observational data to examine how seasonal food availability impacts the feeding ecology of montane forest chimpanzees. We examine seasonal changes in chimpanzee diet and fallback foods (FBFs) using instantaneous scan samples and fecal analyses, supported by inspection of feeding remains. Chimpanzee fruit abundance peaked during the major dry season, with a consequent change in chimpanzee diet reflecting the abundance and diversity of key fruit species. Terrestrial herbaceous vegetation was consumed throughout the year and is defined as a “filler” FBF. In contrast to studies conducted in lower‐elevation chimpanzee sites, figs (especially Ficus lutea) were preferred resources, flowers were consumed at seasonally high rates and the proportion of non‐fig fruits in the diet were relatively low in the current study. These divergences likely result from the comparatively low environmental diversity and productivity in higher‐elevation environments.     

Prostaglandin E2 inhibits the activation of cloned T cell hybridomas

To minimize complicating interactions inherent in heterogeneous cell populations, we used a panel of cloned murine autoreactive (E8.A1) and antigen-specific (HEL.C10, HEL.B14) T cell hybridomas to examine the effect of prostaglandin E2 (PGE2) on T cell activation. These T cells secrete interleukin 2 (IL 2) when co-cultured with a cloned population of I region-matched stimulator cells (TA3), or with mitogenic signals in the absence of TA3 stimulator cells. Physiologic concentrations of PGE2 inhibited the induction of IL 2 secretion by the T cell hybridomas tested, when they were activated either by TA3 cells or by mitogenic signals. IL 2 production was inhibited in a dose-dependent manner by concentrations of PGE2 between 10(-7) and 10(-11) M, with 50% inhibition occurring at 10(-10) M. Pretreatment of the T hybridoma cells with 10(-7) M PGE2 for 1 hr before culture also resulted in marked inhibition of IL 2 secretion. Similar pretreatment of the TA3 cells did not affect their ability to activate the T cell hybridomas. PGE2 at 10(-8) M induced a 30-fold increase in cAMP levels within 25 min of addition to culture of the E8.A1 T cell hybridoma, but caused no significant elevation of cAMP levels in TA3 cells. The direct addition of dibutyryl cAMP (dcAMP) to cultures of E8.A1 cells resulted in marked inhibition of IL 2 secretion when stimulated by TA3 or by mitogenic signals, with an average of 80% inhibition occurring at 10(-4) M dcAMP. PGE2 and dcAMP also inhibited the growth of E8.A1 cells. Initially, cell growth was virtually halted, but began to recover between 24 and 48 hr after the addition of either PGE2 or dcAMP. Neither PGE2 nor dcAMP inhibited the division of TA3 cells. High affinity binding sites for PGE2 were detected in the E8.A1 T cell hybridomas with an apparent Kd of 7.6 X 10(-10) M, which is consistent with the functional data. No specific binding was detected in the TA3 stimulator cells. These findings suggest that the immunosuppressive effects of PGE2 are localized to the T cell, are receptor regulated, and may be mediated by the associated increase of cAMP levels in the T cell hybridomas.     

Evidence Inconsistent with the Blaauw Model of Phototropism

The Blaauw model of phototropism equates the inhibition of growthat the illuminated side of a unilaterally illuminated organwith the blue light inhibition of overall organ extension evidentwhen some shoots are exposed to uniform blue light However,a study of the growth responses of Avena coleoptiles exposedto omnilateral, equal bilateral, unequal bilateral and unilateralblue light has revealed some light induced growth rate changeswhich cannot be explained by the Blaauw model. The growth responsesof cells at the illuminated and shaded sides of phototropicallystimulated coleoptiles seem to depend on the existence of alight gradient across the whole organ rather than the absolutelevels of light at either side. Key words: Phototropism, Avena coleoptile, Blaauw hypothesis, Blue light, Growth inhibition     

Escherichia coli CAN lacks a tRNA-processing nuclease.

Escherichia coli strain CAN is unable to support the growth of bacteriophage T4 strains requiring the suppressor function of T4 tRNASer. Biochemical analysis of the mutant strain revealed that it is deficient in a RNase which acts on the artificial tRNA precursor tRNA-C-U.     

Kinetics of beta-glucuronidase induction by androgen. Genetic variation in the first order rate constant

Measurements of enzyme activity, rates of protein synthesis, and mRNA activity suggest that the induction of beta-glucuronidase in mouse kidney in response to androgen is regulated at a pretranslational level. Following an initial lag period, the rate and extent of induction follow the rules of simple turnover kinetics and can be described in terms of a zero order rate constant for acquisition of mRNA activity (ka) and a first order rate constant for loss of activity (kb). Genetic variation in kb, described here for the first time, alters the half-time and extent of induction. Variation in kb is independent of previously described variation in ka and, unlike changes in ka, is not associated with change in the lag time. The DNA sequences determining kb, like those determining ka, are genetically linked to the structural gene for beta-glucuronidase. Following the removal of androgen, beta-glucuronidase activity, rate of synthesis, and mRNA activity all decline rapidly with half-lives of 1-2 days. Even in the most rapidly inducing strains, this is significantly faster than the half-time for induction determined by kb. Furthermore, genetic variation in kb does not affect the rate of de-induction. These facts suggest that kb may not describe the turnover of beta-glucuronidase mRNA, but rather the turnover of another step in the induction process.     

The Enucleation of Cells on Plastic Leighton Coverslips

A simple enucleation technique that facilitates autoradiographic and electron microscopic examination of cytoplasms is described. Cells were grown on commercially available plastic Leighton coverslips and these were centrifuged in the presence of cytochalasin B. The centrifugation requires no special holders and only a high speed centrifuge. Enucleation frequencies of greater than 90% were obtained for Chinese hamster fibroblasts and mouse B-82 cells.     

Teixeiria lusitanica, a new fossil flower from the Early Cretaceous of Portugal with affinities to Ranunculales

A charcoalified fossil flower bud of a new genus and species (Teixeiria lusitanica) is described from the Early Cretaceous of Portugal. The flower is actinomorphic and unisexually male. At the base of the bud there are several bracts of different sizes, which are followed by sepal-like and petal-like tepals. Bracts and perianth organs seem to be arranged spirally and to exhibit transitions between different organ categories. The androecium has numerous stamens in two sizes, but with unclear arrangement. Pollen is small and tricolpate with a perforate tectum and a densely columellate infratectal layer. No carpels or remains of carpels could be observed on the floral axis. Teixeiria lusitanica shows most affinities to members of Ranunculales. There are also some similarities with Berberidopsis (Berberidopsidaceae, Berberidopsidales) and members of the Saxifragales (Hamamelidaceae and Daphniphyllaceae).     

Management of the Wadden Sea

The Wadden Sea situated along the North Sea coasts of Denmark, the Federal Republic of Germany and The Netherlands represents one of the world's largest bar-built type of estuaries. The area is a typical sedimentation and mineralization basin, with a large influx of organic matter from the adjoining North Sea, consequently a delicate oxygen balance and a rich benthic macrofauna, poor in species, which serves as food for juveniles of some commercially important North Sea fishes and for large numbers of migrating and wintering waders and waterfowl. Past and present activities of the human society in the area include fisheries (mainly for shrimp and mussels, semi-culture), shipping, land reclamation, recreation, dredging for sand and shells, and waste discharge from industries and human communities. Until the present these activities, although sometimes conflicting, did not fundamentally affect the area and its biota (pollution excluded), but future claims, including the construction of large deep-sea harbours, drilling for natural gas and oil, large-scale land reclamation and increased industrialization etc., might gradually induce degradation. For instance, area reduction by continued land reclamation could lead to irreversible losses of specific biotopes (e. g. salt-marshes, mud-flats), which could affect the size of bird and fish populations in a much wider region. Increased pollution, which has already inflicted damage on bird and seal populations, could reduce the fauna and hence the value of the area as a natural sanctuary. In the event of a proposal for a new human activity in the area, the present standing practice in the countries concerned requires an evaluation of its safety and economic aspects and its environmental impact. However, the various plans are considered separately and there is a general need for integrated management of the area.     

Method of clonal micropropagation of different willow species and hybrids

Conditions of cultivation and micropropagation of selected biotypes of five willow species (Salyx dasyclados Wimm., S. caspica Pall., S. triandra L., S. purpurea L., and S. viminalis L.) and two hybrids (×S. acuminata S. and ×S. palustris Host.) were optimized. Data on in vitro propagation of S. caspica, S. triandra, S. purpurea together with hybrids S. acuminata and S. palustris were obtained for the first time. It has been demonstrated that the outcome of cultivation and propagation of willows strongly depends on genotypic peculiarities of initial plants. The optimal terms of isolation and sterilization of single-node segments for obtaining 50–75% of aseptic viable developing cultures were estimated. The nutritive media were selected providing induction of stem development (to 67%), their rooting (to 91%), elongation (to 3–6 cm), and multiplication (propagation coefficient of 4). The designed method (adopted to different genotypes) can be applied for obtaining aseptic in vitro cultures serving as initial plant material for genetic transformation and mass propagation of plants with new agriculturally valuable characteristics which are of interest for construction of bioenergetic plantations and for needs of the paper industry.