Growth,survival and reproduction in<Emphasis Type="Italic">Chlorella vulgaris</Emphasis> and<Emphasis Type="Italic">C. variegata</Emphasis> with respect to culture age and under different chemical factors

Batch cultures of Chlorella vulgaris and C. variegata reproducing about twice every 5 d within 0-15 d had vegetative cells and autospore mother cells in the ratio of about 19 : 1. Continuous slow or negligible and/or no growth in > 15-d-old control cultures or in young cultures supplied with the antibiotics streptomycin, penicillin, amoxycillin (10-1000 ppm) or tetracycline (10, 100 ppm), and pesticides carbofuran, gammaxine, moticop or iralon (1-100 ppm) was due to slow autospore mother cells dehiscence (leading to an increase in their percentage); while negligible and/or no growth of both algal species in sewage water (100, 25%), detergent (0.1-1%), petrol or kerosene (5-20 %), benzene, toluene or phenol (5, 10%) and pesticides rogor or endosulfan (1, 10 ppm) was due to vegetative cells failure to differentiate into auto-spore mother cells (leading to decreased/zero autospore mother cells percentage) and/or rapid death of all cells. C. variegata was equally or slightly more sensitive to different chemical stress than C. vulgaris.     

Wax removal for accelerated cotton scouring with alkaline pectinase

A rational approach has been applied to design a new environmentally acceptable and industrially viable enzymatic scouring process. Owing to the substrate specificity, the selection of enzymes depends on the structure and composition of the substrate, i.e. cotton fibre. The structure and composition of the outer layers of cotton fibre has been established on the basis of thorough literature study, which identifies wax and pectin removal to be the key steps for successful scouring process. Three main issues are discussed here, i.e. benchmarking of the existing alkaline scouring process, an evaluation of several selected acidic and alkaline pectinases for scouring, and the effect of wax removal treatment on pectinase performance. It has been found that the pectinolytic capability of alkaline pectinases on cotton pectin is nearly 75% higher than that of acidic pectinases. It is concluded that an efficient wax removal prior to pectinase treatment indeed results in improved performance in terms of hydrophilicity and pectin removal. To evaluate the hydrophilicity, the structural contact angle (theta) was measured using an auto-porosimeter.     

p27Kip1 regulates T cell proliferation

Our studies addressed the mechanism by which serum acts in conjunction with T cell receptor (TCR) agonists to promote the proliferation of primary splenic T cells. When added to resting splenocytes, TCR agonists initiated G(0)/G(1) traverse and activated cyclin D3-cdk6 complexes in a serum-independent manner. On the other hand, both TCR agonists and 10% serum were required for the activation of cyclin E-cdk2 and cyclin A-cdk2 complexes and the entry of cells into S phase. Serum facilitated cdk2 activation by maximizing the extent and extending the duration of the TCR-initiated down-regulation of the cdk2 inhibitor, p27(Kip1). Although p27(Kip1) levels were reduced (albeit submaximally) in cells stimulated in serum-deficient medium, nearly all of the cdk2 complexes in these cells contained p27(Kip1). In contrast, in cells receiving TCR agonist and 10% serum, little if any p27(Kip1) was present in cyclin-cdk2 complexes. Unlike wild-type splenocytes, p27(Kip1)-null splenocytes did not require serum for cdk2 activation or S phase entry whereas loss of the related cdk2 inhibitor, p21(Cip1), did not override the serum dependence of these responses. We also found that cdk2 activation was both necessary and sufficient for maximal expression of cdk2 protein. These studies provide a mechanistic basis for the serum dependence of T cell mitogenesis.     

Possible consequences of genes of major effect: transient changes in the G-matrix

Understanding the process of evolutionary divergence requires knowledge of the strength, form, and targets of selection, as well as the genetic architecture of the divergent traits. Quantitative genetic approaches to understanding multivariate selection and genetic response to selection have proven to be powerful tools in this endeavor, particularly with respect to short-term evolution. However, the application of quantitative genetic theory over periods of substantial phenotypic change is controversial because it requires that the requisite genetic parameters remain constant over the period of time in question. We show herein how attempts to determine the stability of key genetic parameters may be misled by the many genes of small effect type of genetic architecture generally assumed in quantitative genetics. The presence of genes of major effect (GOMEs) can alter the genetic variance-covariance matrix dramatically for brief periods of time, significantly alter the rate and trajectory of multivariate evolution, and thereby mislead attempts to reconstruct or predict long term evolution.     

On indirect genetic effects in structured populations

Indirect genetic effects (IGEs) occur when the phenotype of an individual, and possibly its fitness, depends, at least in part, on the genes of its social partners. The effective result is that environmental sources of phenotypic variance can themselves evolve. Simple models have shown that IGEs can alter the rate and direction of evolution for traits involved in interactions. Here we expand the applicability of the theory of IGEs to evolution in metapopulations by including nonlinear interactions between individuals and population genetic structure. Although population subdivision alone generates some dramatic and nonintuitive evolutionary dynamics for interacting phenotypes, the combination of nonlinear interactions with subdivision reveals an even greater importance of IGEs. The presence of genetic structure links the evolution of interacting phenotypes and the traits that influence their expression ("effector traits") even in the absence of genetic correlations. When nonlinear social effects occur in subdivided populations, evolutionary response is altered and can even oppose the direction expected due to direct selection. Because population genetic structure allows for multilevel selection, we also investigate the role of IGEs in determining the response to individual and group selection. We find that nonlinear social effects can cause interference between levels of selection even when they act in the same direction. In some cases, interference can be so extreme that the actual evolutionary response to multilevel selection is opposite in direction to that predicted by summing selection at each level. This theoretical result confirms empirical data that show higher levels of selection cannot be ignored even when selection acts in the same direction at all levels.     

Topology and structure of the C1q-binding site on C-reactive protein

The host defense functions of human C-reactive protein (CRP) depend to a great extent on its ability to activate the classical complement pathway. The aim of this study was to define the topology and structure of the CRP site that binds C1q, the recognition protein of the classical pathway. We have previously reported that residue Asp(112) of CRP plays a major role in the formation of the C1q-binding site, while the neighboring Lys(114) hinders C1q binding. The three-dimensional structure of CRP shows the presence of a deep, extended cleft in each protomer on the face of the pentamer opposite that containing the phosphocholine-binding sites. Asp(112) is part of this marked cleft that is deep at its origin but becomes wider and shallower close to the inner edge of the protomer and the central pore of the pentamer. The shallow end of the pocket is bounded by the 112-114 loop, residues 86-92 (the inner loop), the C terminus of the protomer, and the C terminus of the pentraxin alpha-helix 169-176, particularly Tyr(175). Mutational analysis of residues participating in the formation of this pocket demonstrates that Asp(112) and Tyr(175) are important contact residues for C1q binding, that Glu(88) influences the conformational change in C1q necessary for complement activation, and that Asn(158) and His(38) probably contribute to the correct geometry of the binding site. Thus, it appears that the pocket at the open end of the cleft is the C1q-binding site of CRP.     

Animation of the dynamical events of the elongation cycle based on cryoelectron microscopy of functional complexes of the ribosome

Using three-dimensional cryoelectron microscopy, the binding positions of tRNA and elongation factors EF-G and EF-Tu (the latter complexed with aminoacyl tRNA and GTP) on the ribosome were determined in previous studies. On the basis of these studies, the dynamical events that take place in the course of the elongation cycle of protein synthesis have been animated. The resulting 3-min movie is accessible on the website of this journal (http://www. idealibrary.com). The following article provides a brief annotation of those frames of the movie for which experimental support is available.