Weed macaques: The evolutionary implications of macaque feeding ecology

Patterns of feeding ecology among the living macaques conform poorly with recognized phyletic distinctions within the genus because there is an important ecological division which cross-cuts phyletic groupings. This division, between weed species and non-weed species, is based on the differing abilities of macaques to tolerate and even prosper in close association with human settlements. Based on available information about their ecology in the wild, we tentatively assign macaque species to these two categories. Finally, we consider the implications of our argument for scenarios of the initial spread of the macaques.     

Value of routine follow up of women treated for early carcinoma of the breast.

The value of routine follow up of women treated for early breast cancer by mastectomy with or without postoperative radiotherapy was assessed retrospectively. Over eight years 546 patients made 6863 clinic visits, during which 192 first relapses were detected. Ninety three relapses were detected at scheduled (routine) visits and 99 at unscheduled (interval) visits. First relapses within the treated area or in the contralateral breast were detected significantly more commonly at routine visits than were first metastatic relapses (66/89 (74%) compared with 27/103 (26%)). Patients whose local relapse was detected at a routine visit had a significantly better survival than those whose local relapse was detected at an interval visit. A relapse that was potentially curable (local or in the contralateral breast) was detected at 66 (1%) of 6764 routine visits, but only 26 (39%) of these patients remained free of disease. It is concluded that the intensity of follow up of such patients could be reduced without any adverse effect on prognosis but with appreciable financial and other benefits.     

Interactions ofCandida albicans with bacteria and salivary molecules in oral biofilms

The yeastCandida albicans coaggregates with a variety of streptococcal species, an interaction that may promote oral colonization by yeast cells.C. albicans andCandida tropicalis are the yeasts most frequently isolated from the human oral cavity and our data demonstrate that both these species bind toStreptococcus gordonii NCTC 7869 while two otherCandida species (Candida krusei andCandida kefyr) do not. Adherence ofC. albicans was greatest when the yeast had been grown at 30° C to mid-exponential growth phase. For 21 strains ofC. albicans there was a positive correlation between the ability to adhere toS. gordonii and adherence to experimental salivary pellicle. Whole saliva either stimulated or slightly inhibited adherence ofC. albicans toS. gordonii depending on the streptococcal growth conditions. The results suggest that the major salivary adhesins and coaggregation adhesins ofC. albicans are co-expressed.     

Electrophoretic karyotypes of the elm tree pathogen Ophiostoma ulmi (sensu lato)

Pulsed field gel electrophoresis using OFAGE, TAFE, and CHEF systems has been used to more fully characterize karyotypic variation within the two closely related fungal species of Ophiostoma ulmi sensu lato. Twelve wild-type and laboratory strains, representing the less agressive species O. ulmi and both of the biotypes of the more aggressive species O. novo-ulmi were studied and their karyotypes determined. Depending on the strain, a minimum of four to a minimum of eight chromosomal DNA bands were present that fall into three distinct size classes, with one exception. Strain CESSI6K (O. novo-ulmi, North American aggressive subgroup) contains a unique chromosomal DNA band which comigrated near a Saccharomyces cerevisiae chromosome of 0.95 Mb. This unique band was the smallest O. ulmi s. l. chromosomal DNA observed. Seven of the twelve strains shared a common chromosomal DNA banding pattern, whereas each of the other five had a unique karyotype. There was no correlation between chromosome profile and species, as some O. novo-ulmi and O. ulmi strains shared common electrophoretic karyotypes.     

A Mechanistic Analysis of Self-thinning in Terms of the Carbon Balance of Trees

The self-thinning behavior of a monoculture forest is examinedfrom a mechanistic viewpoint, in terms of the carbon balanceof trees at the stand level. Two approaches are described: thefirst is based on simple assumptions concerning the balancebetween growth, photosynthesis and respiration; the second usesthe process-based I.T.E. EDINBURGH FOREST model, extended toinclude tree birth and death, to examined the assumptions ofthe first approach at a more mechanistic level and to interpretthe observed variation in the responses to shading and soilfertility in terms of a single model. The first approach leads to a power law relation m n ^-1/y betweenmean biomass per tree (m) and the number of trees per unit groundarea (n), where y is the exponent characterising the rate atwhich respiration (r) scales with biomass (i.e. r m^y). Forvalues of y less than 1, m and n are predicted to increase anddecrease, respectively, as powers of time (t) such that thebiomass per unit ground area (M) increases linearly with t forany value of y. When y equals 1, m and n vary exponentiallywith t and M remains constant. When r is assumed to be proportional to stem cambium surfacearea, the value of y is shown to lie in the range 0·5to 1 depending on the rate of stem taper. This leads to slopeson a log m vs. log n self-thinning plot in range -1 to -2 andtypically around -1·5 for rates of taper based on mechanicalrequirements. For the second approach, the I.T.E. EDINBURGH FOREST model,a previously published mechanistic model of plantation growthat the stand level (Thornley, 1991), is extended to naturalstands by introducing average stem birth and death rates thatare functions of the carbon and nitrogen substrate status oftrees. Growth of even-aged and mixed-age forest over about 500years is simulated under a variety of environmental and physiologicalconditions. In general, the forest model predicts a curved log m vs. logn thinning line, but has a reasonably well-defined linear sectionunder most conditions. The slope of the linear portion flattensas the rate at which cambium surface area scales with structuralbiomass increases, in qualitative agreement with the analyticalprediction of the first approach. Quantitative differences betweenthe two approaches are interpreted in terms of the process representedin the forest model. In general, the height of the thinningline increases with irradiance, but is relatively insensitiveto soil nitrogen, with no change in slope in either case. However,at very low irradiance or soil nitrogen levels, the slope flattenscontinuously and the entire thinning line becomes markedly non-linear.Even-aged stands and mixed-age stands have different thinningslopes.Copyright 1993, 1999 Academic Press Self-thinning, carbon balance, mechanistic model, forest growth, respiration     

Inhibition of cell division initiation by an imbalance in the ratio of FtsA to FtsZ.

Elevated levels of FtsA protein block cell division at a very early stage, similar to that caused by inhibition of the action of FtsZ. In contrast, overexpression of FtsA and FtsZ together does not block division. A specific ratio of FtsA to FtsZ protein, therefore, is required for cell division.     

Regulation of expression of the ftsA cell division gene by sequences in upstream genes.

The essential cell division genes ftsQ and ftsA overlap by 1 bp (A. C. Robinson, D. J. Kenan, G. F. Hatfull, N. F. Sullivan, R. Spiegelberg, and W. D. Donachie. J. Bacteriol. 160:546-555, 1984; Q.-M. Yi, S. Rockenbach, J. E. Ward, and J. F. Lutkenhaus. J. Mol. Biol. 184:399-412, 1985). We have previously shown that ftsA can be expressed from a weak promoter located within the ftsQ gene (Robinson et al., J. Bacteriol. 160:546-555, 1984). We report here the effects on ftsA expression of a series of deletions within ftsQ. We find that two regions upstream of the promoter are important in its expression. When both are present, ftsA is expressed, as is also the case when both are absent. The two regulatory elements (O1 and O2) have 9-bp sequences, of which 8 bp are identical.     

Control of cell volume in the J774 macrophage by microtubule disassembly and cyclic AMP

We have explored the possibilities that cell volume is regulated by the status of microtubule assembly and cyclic AMP metabolism and may be coordinated with shape change. Treatment of J774.2 mouse macrophages with colchicine caused rapid microtubule disassembly and was associated with a striking increase (from 15-20 to more than 90 percent) in the proportion of cells with a large protuberance at one pole. This provided a simple experimental system in which shape changes occurred in virtually an entire cell population in suspension. Parallel changes in cell volume could then be quantified by isotope dilution techniques. We found that the shape change caused by colchicine was accompanied by a decrease in cell volume of approximately 20 percent. Nocodozole, but not lumicolchicine, caused identical changes in both cell shape and cell volume. The volume loss was not due to cell lysis nor to inhibition of pinocytosis. The mechanism of volume loss was also examined. Colchicine induced a small but reproducible increase in activity of the ouabain-sensitive Na(+), K(+)-dependent ATPase. However, inhibition of this enzyme/transport system by ouabain did not change cell volume nor did it block the colchicines-induced decrease in volume. One the other hand, SITS (4’acetamido, 4-isothiocyano 2,2’ disulfonic acid stilbene), an inhibitor of anion transport, inhibited the effects of colchicines, thus suggesting a role for an anion transport system in cell volume regulation. Because colchicine is known to activate adenylate cyclase in several systems and because cell shape changes are often induced by hormones that elevate cyclic AMP, we also examined the effects of cyclic AMP on cell volume. Agents that act to increase syclic AMP (cholera toxin, which activates adenylate cyclase; IBMX, and inhibitor of phosphodiesterase; and dibutyryl cyclic AMP) all caused a volume decrease comparable to that of colchicine. To define the effective metabolic pathway, we studied two mutants of J774.2, one deficient in adenylate cyclase and the other exhibiting markedly reduced activity of cyclic AMP-dependent protein kinase. Cholera toxin did not produce a volume change in either mutant. Cyclic AMP produced a decrease in the cyclase-deficient line comparable to that in wild type, but did not cause a volume change in the kinase- deficient line. This analysis established separate roles for cyclic AMP and colchicine. The volume decrease induced by cyclic AMP requires the action of a cyclic AMP-dependent protein kinase. Colchicine, on the other hand, induced a comparable volume change in both mutants and wild type, and thus does not require the kinase.