Ubiquitin ligases play an important regulatory role in the control of protein degradation processes via the ubiquitin/26S proteasome pathway in eukaryotes. These enzymes participate in substrate specification and mediate the transfer of ubiquitin to target proteins. A large number of ubiquitin ligases are predicted in the eukaryotes whose genomes have been sequenced; in Arabidopsis thaliana more than 1300 genes are thought to encode ubiquitin ligases. At least three classes of ubiquitin ligases are present in Arabidopsis, one of which comprises about 470 RING zinc-finger domain proteins. Within this class we have characterized the ATL family that encodes a RING-H2 finger. We identified 80 members of this family in A. thaliana and 121 in Oryza sativa. About 60% of the rice ATLs are clustered with A. thaliana ATLs, and in many cases the gene products showed sequence similarities beyond the ATL's conserved features, suggesting that they could be orthologous genes. Ninety percent of the ATLs are intronless genes, suggesting that the structure of the basic ATL protein may have evolved as a functional module. We carried out a survey of T-DNA insertions in 30% of the Arabidopsis ATL genes and screened for possible phenotypes. Four of these genes are likely to be essential for viability, since homozygous plants for the T-DNA insertion were not recovered. One of them, ATL8, is mainly expressed in young siliques, suggesting a role during embryogenesis. We also recovered a line carrying a T-DNA insertion in ATL43 that showed an ABA-insensitive phenotype, suggesting a role of this gene in the ABA response. The organization of ATLs in Arabidopsis and rice in this study will be a valuable comprehensive guide for this multigene family.
Objective: To evaluate the association between stunting in children and maternal short stature, controlling for potential environmental confounders. Design: 1988 Mexico National Nutrition Survey. Setting: Mexico Subjects: The ®nal sample size was 4663 pairs of children (`5 y) and their mothers (12 ± 49 y) from a total of 13 236 surveyed houses. Main outcome measures: Stunting (height-for-age Z-scores`7 2). Results: The prevalence of stunting in children was 19%, and 10% of the mothers exhibited short stature (`145 cm). In the crude analysis, mothers with short stature were signi®cantly more likely to have stunted children (odds ratio (OR) 4.0; 95% con®dence interval (CI) 3.2 ± 4.8; P-value`0.001). In a multiple logistic regression model the OR for child stunting was reduced, but remained signi®cant OR 2.0; 95% CI 1.6 ± 2.6; P-value`0.001) after adjustment for region, urbanarural residence, socio-economic status, household size, child age and presence of infection in the past 14 d, and maternal age, body mass index (BMI), and educational level. Adjusted ORs varied between regions (Mexico City, OR 3.9; North Mexico, OR 3.1; Central Mexico, OR 2.0; South Mexico, OR 1.6. Comparison of crude vs adjusted estimates pointed to regional differences in the proportion of association between maternal and child short statures explained by environmental determinants. Conclusions: Maternal stature, re¯ecting her potential height and early environment, appeared to contribute to child height independently of the shared risk factors that could affect stature. Nonetheless, we could explain much of the association between stunting in children and maternal short stature by environmental factors, and part of the residual variability may be due to unmeasured determinants. Regional differences pointed to a predominance of environmental factors in explaining child stunting in poorer regions.
Several countries, including Mexico, are experiencing changes in health patterns that are characterized by an increase in the prevalence of chronic diseases and changes in the principal causes of death, coexisting with deficiencies in the intake of energy and micronutrients, particularly in children. Several factors may explain these changes, including dietary habits. To evaluate food consumption in a population undergoing a health transition, a food-frequency questionnaire was developed, validated, and used to study the dietary determinants of chronic diseases in Mexico. Nutrient deficiency and the relation between maternal child-feeding behaviors and dietary intake by the child were evaluated with use of 24-h recalls, food-frequency methods. and estimation of food intake by observation. The observation method was extremely useful for studies in rural areas.
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