Homologues of the Cf-9 disease resistance gene (Hcr9s) are present at multiple loci on the short arm of tomato chromosome 1

The tomato Cf-4 and Cf-9 genes map at a genetically complex locus on the short arm of chromosome 1 and confer resistance against Cladosporium fulvum through recognition of different pathogen-encoded avirulence determinants. Cf-4 and Cf-9 are members of a large gene family (Hcr9s, Homologues of Cladosporium fulvum resistance gene Cf-9), some of which encode additional distinct recognition specificities. A genetic analysis of the majority of Hcr9s suggests that their distribution is spatially restricted to the short arm of chromosome 1. Two loci of clustered Hcr9 genes have been analyzed physically that mapped distal (Northern Lights) and proximal (Southern Cross) to the Cf-4/9 locus (Milky Way). Sequence homologies between intergenic regions at Southern Cross and Milky Way indicate local Hcr9 duplication preceded cluster multiplication. The multiplication of clusters involved DNA flanking Hcr9 sequences as indicated by conserved lipoxygenase sequences at Southern Cross and Milky Way. The similar spatial distribution of Hcr9 clusters in different Lycopersicon spp. suggests Hcr9 cluster multiplication preceded speciation.     

Ergonomic criteria in large-scale engineering design--II. Evaluating and applying requirements in the real world of design.

Ergonomic standards to be used in engineering design are at present being developed throughout the world. However, not much is known about how ergonomic criteria function in an organizational setting. This study investigates how engineering designers in two large-scale engineering projects evaluate ergonomic criteria that are part of the design requirements in the projects. The designers state a clear preference for specific criteria. We also show how all design criteria are subject to organizational constraints, and that specific formulations are not a guarantee for the implementation of ergonomic criteria. Emphasising a few specific criteria might have an educational impact on the designers. The active involvement of an HF specialist is also critical to ensure a positive outcome for ergonomic criteria in the design negotiation process.     

Systematic back-calculation protocol and prediction of resilient modulus for MEPDG

A research focusing on the characterisation of representative local material properties was conducted to facilitate the full implementation of the Mechanistic-Empirical Pavement Design Guide for roadway designs in Wyoming. As part of the test program, falling weight deflectometer deflection data were collected from 25 test sites in Wyoming for back-calculation of subgrade resilient modulus. Also, subgrade materials from these test sites were sampled for laboratory resilient modulus measurement in accordance with the AASHTO T 307. The back-calculation is a user-dependent procedure and produces a non-unique resilient modulus estimation. To alleviate this limitation, this paper focuses on the recent development of a systematic back-calculation protocol for subgrade resilient modulus using MODCOMP6 software. The protocol is intended for use on a flexible pavement with a crushed base. The proposed procedure discusses pre-analysis checks, seed modulus adjustment, pavement structure adjustment and program termination criteria. A correlation study was conducted to correct back-calculated resilient modulus to laboratory-equivalent values. The results conclude that a non-zero intercept linear regression model provides a better correlation than the widely used zero intercept linear regression model. Furthermore, better correlations are achieved when the back-calculated resilient modulus of a lower subgrade layer and resilient modulus measured at higher laboratory test sequences Nos. 11 to 15 are considered. The non-zero model based on M_r test sequence No. 14 and lower subgrade layer yields the best correlation. For the zero model, a C-factor of 0.645 based on M_r test sequence No. 15 and lower subgrade layer yields the best correlation.     

Angiogenesis during primate placentation in health and disease

Normal embryonic development is dependent upon a sufficient oxygen, nutrient and waste exchange through the placenta. In primates including humans, this exchange is attained by successful haemochorial placentation which requires the transformation of maternal intramyometrial spiral arterioles by trophoblast invasion to gain uteroplacental circulation, and establishment and maintenance of a competent fetoplacental vasculature. Thus, trophoblast and endothelial cell differentiation, proliferation and invasion occurring during placentation have to be tightly regulated. This review focuses on the diverse developmental steps during haemochorial placentation in humans and other primates and the possible involvement of angiogenic growth factors (vascular endothelial growth factor (VEGF) and angiopoietins (Ang)) in these processes, highlighting the importance of specific actions of angiogenic ligand-receptor pairs. It is hypothesized that VEGF/VEGF-R1 and Ang-1/Tie receptor 2 (Tie-2) may regulate trophoblast differentiation and invasion; VEGF/VEGF-R2 and Ang-1/Tie-2 may promote fetoplacental vascular development and stabilization; and Ang-2/Tie-2 may be involved in maternal vascular remodelling. The importance of a tight regulation of angiogenic factors and their endogenous antagonists for normal development of the placenta is demonstrated by failure of this system, resulting in abnormal placenta vascularization and trophoblast invasion associated with intrauterine growth retardation or pre-eclampsia.     

Angiogenesis and microvascular development in the marmoset (Callithrix jacchus) endometrium during early pregnancy

The aim of the study was to describe and quantify the changes in the maternal vasculature and angiogenesis during early pregnancy in the marmoset endometrium using bromodeoxyuridine (BrdU) to identify proliferating cells, CD31 to label endothelial cells and dual staining to identify proliferating endothelial cells. Non-pregnant animals from mid- and late secretory stages were studied and compared with pregnant animals at weeks 2, 3 and 4 of pregnancy. Qualitative and morphometric analyses of angiogenesis and vascular area were performed. The results show that pregnancy is associated with increasing angiogenesis in the upper zone of the endometrium, becoming significantly increased at 3 weeks. This is associated with an increase in the vessel area and diameter in this zone. These results provide the platform from which to design studies in which specific angiogenic factors can be targeted in vivo during early pregnancy in order to determine their role in regulating these vascular changes.     

Localization of mRNA for vascular endothelial growth factor (VEGF), angiopoietins and their receptors during the peri-implantation period and early pregnancy in marmosets (Callithrix jacchus)

Implantation of a blastocyst into a receptive endometrium is a prerequisite for successful pregnancy. Angiogenesis is a key event in this process but the mechanisms by which localized changes in vascular permeability and angiogenesis occur have yet to be elucidated. Vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 and VEGFR-2 have been implicated as key players in vascular remodelling and placentation. Angiopoietins also appear to have a significant role in regulation of blood vessel growth, maturation and regression. The aim of this study was to describe the molecular regulation of angiogenesis in the first month of pregnancy in marmosets and to address the putative physiological roles for these factors. Uteri were studied at weeks 2, 3 and 4 of pregnancy and compared with late secretory non-pregnant endometrium. Implantation in marmosets occurs at day 11 of pregnancy; hence, these time points were chosen so that the peri-implantation period and very early pregnancy could be studied. mRNAs for VEGF, VEGFR-1 and VEGFR-2, angiopoietin 1, angiopoietin 2 and their receptor Tie-2 were localized and quantified by in situ hybridization. Endothelial cells were identified by CD31 immunocytochemistry. VEGF mRNA was present in all compartments except endothelial cells, and its expression generally increased throughout pregnancy except in upper zone glandular epithelium and luminal epithelium, where a decrease in expression was observed. VEGF receptor mRNAs were found in endothelial cells of the upper zones immediately surrounding glandular epithelium. Angiopoietin 1 mRNA was localized to glandular epithelium of the upper and lower zones throughout pregnancy, and increased in stroma at week 4. Expression of angiopoietin 2 mRNA was localized exclusively to endothelial cells of large luminal vessels and was higher in endometrium from marmosets at week 4 of pregnancy than in endometrium from all other stages. These data provide comprehensive evidence that VEGFR-1 and -2, and angiopoietin 1, angiopoietin 2 and Tie-2 interactions may be involved in the preparation of endometrium for implantation, remodelling of the maternal vasculature and trophoblast invasion during the peri-implantation period in this primate species.