Seed size variation: magnitude, distribution, and ecological correlates

We examined seed-mass variation in 39 species (46 populations) of plants in eastern-central Illinois, USA. The coefficient of variation of seed mass commonly exceeded 20%. Significant variation in mean seed mass occurred among conspecific plants in most species sampled (by hierarchical ANOVA), averaging 38% of total variance. For most species, within-plant variation was the larger component of total variance, averaging 62% of total variance. Variation in seed mass among fruits within crops was significant in most species tested.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42741/1/10682_2005_Article_BF02067274.pd

A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

New insights into acne pathogenesis: Exploring the role of acne-associated microbial populations

AbstractAcne vulgaris, a prevalent disorder of the skin, is found to increase the incidence of suicidal ideation in acne patients (∼7.1%). This creates a dilemma in the mind whether acne is a life threatening disease among humans. The main inducer for this multifactorial disease is microbial fluctuation of common resident microbes on the skin with each microbe possessing their own purpose and style in protecting the human body. For acne progression, the microbial population has to get around the defense barriers of the host skin and be able to also resist them in order to survive. These matters have been resolved by their pathogenic lifecycle and associated virulence factors coded within their pathogenic islands in the single circular chromosome. This review addresses the different microbial populations residing in acne lesions and promoting acne by emphasizing their pathogenic mechanisms and the genes associated with virulence factors involved in the development of acne. Model systems such as animal models and cell culture models in studying the pathogenic lifestyle of the microbes are also addressed

Differential Effects of Collagen Prolyl 3-Hydroxylation on Skeletal Tissues

<div><p>Mutations in the genes encoding cartilage associated protein (<i>CRTAP</i>) and prolyl 3-hydroxylase 1 (P3H1 encoded by <i>LEPRE1</i>) were the first identified causes of recessive Osteogenesis Imperfecta (OI). These proteins, together with cyclophilin B (encoded by <i>PPIB</i>), form a complex that 3-hydroxylates a single proline residue on the α1(I) chain (Pro986) and has cis/trans isomerase (PPIase) activity essential for proper collagen folding. Recent data suggest that prolyl 3-hydroxylation of Pro986 is not required for the structural stability of collagen; however, the absence of this post-translational modification may disrupt protein-protein interactions integral for proper collagen folding and lead to collagen over-modification. P3H1 and CRTAP stabilize each other and absence of one results in degradation of the other. Hence, hypomorphic or loss of function mutations of either gene cause loss of the whole complex and its associated functions. The relative contribution of losing this complex's 3-hydroxylation versus PPIase and collagen chaperone activities to the phenotype of recessive OI is unknown. To distinguish between these functions, we generated knock-in mice carrying a single amino acid substitution in the catalytic site of P3h1 (<i>Lepre1^H662A</i>). This substitution abolished P3h1 activity but retained ability to form a complex with Crtap and thus the collagen chaperone function. Knock-in mice showed absence of prolyl 3-hydroxylation at Pro986 of the α1(I) and α1(II) collagen chains but no significant over-modification at other collagen residues. They were normal in appearance, had no growth defects and normal cartilage growth plate histology but showed decreased trabecular bone mass. This new mouse model recapitulates elements of the bone phenotype of OI but not the cartilage and growth phenotypes caused by loss of the prolyl 3-hydroxylation complex. Our observations suggest differential tissue consequences due to selective inactivation of P3H1 hydroxylase activity versus complete ablation of the prolyl 3-hydroxylation complex.</p></div

Prolyl 3-hydroxylation at Pro986 in the α2(V) collagen chain.

<p>Mass spectral analysis of Pro986 hydroxylation in tryptic peptides from the α2(V) chain of bone from <i>Lepre1^+/+</i> and <i>Lepre1^H662A/H662A</i> mice (A and B respectively) shows a marked reduction in hydroxylation at this site. The MS/MS fragmentation patterns shown in C and D identified the 765.8²⁺ peptide and its 3-hydroxylated version 773.9²⁺. A portion (40%) of the latter ion was also found by MS/MS to be contributed by a version lacking 3-Hyp but containing 4-Hyp at P978 (taken into account in the 3-Hyp quantitation).</p

<i>Lepre1^H662A/H662A</i> fibroblast procollagen secretion rate and collagen modification is normal.

<p>Analysis of procollagen secretion by the collagen pulse-chase assay suggests that the procollagen secreted from <i>Lepre1^H662A/H662A</i> fibroblasts is similar to <i>Lepre1^+/+</i> fibroblasts (A, B). Additionally, there does not appear to be a decrease in the amount of procollagen secreted from the <i>Lepre1^H662A/H662A</i> fibroblasts in comparison to <i>Lepre1^+/+</i> fibroblasts (A, B). These findings are in contrast to that of the <i>Crtap^−/−</i> fibroblasts, which have an increase in the rate of procollagen secretion (A). Collagen modification was assessed using the collagen steady-state assay. We observed no difference in the migration pattern of procollagen and collagen isolated from <i>Lepre1^+/+</i>(+/+) and <i>Lepre1^H662A/H662A</i> (H662A/H662A) fibroblasts (C). These assays were repeated three times.</p

Histomorphometry of <i>Lepre1^H662A/H662A</i> mice.

<p>By histomorphometry, we were able to confirm the low trabecular bone mass phenotype in the <i>Lepre1^H662A/H662A</i> mice as quantified by decreased bone volume (BV/TV) and trabecular thickness (Tb.Th). We observed no differences in osteoblast and osteoclast parameters, as measured by the number of osteoblasts (N.Ob/BS) and osteoclast surface (OcS/BS). We observed no difference in the kinetic indices of bone formation, as measured by mineral apposition (MAR), mineralizing surface (MS/BS) and bone formation rate (BFR/TV) and in osteoid parameters, as measured by osteoid volume (OV/BV) and osteoid surface (OS/BS) (mean ± SD, N = 9, both genotypes).</p

Hydroxylation status at different collagen sites.

<p>Table shows the percent 3-hydroxylation of proline at known sites of potential occupancy in type I and type II collagen of bone and cartilage determined by mass spectrometry.</p

Table comparing <i>Lepre1^H662A/H662A</i> phenotype to established OI mouse models.

<p>In contrast to the established KO mouse models, the <i>Lepre1^H662A/H662A</i> mice have a wild-type appearance, no delay in growth curve, and normal cortical bone. In addition, there is a slight decrease in collagen diameter.</p