Use and nutritive value of talet beans,Amphicarpaea bracteata (Fabaceae: Phaseoleae) as human food in Puebla, México

Species of the genus Amphicarpaea have been reported as edible (for human consumption or as fodder) in Asia and North America. In northern Puebla, México, talet, A. bracteata, grows as a weed in multiple cropping systems, and its subterranean fruits are used as food by Nahuas, Totonacs, and Mestizos. This study documents how the seed is harvested during agricultural practices, the way in which the pleasant-tasting seeds are prepared for consumption, and how the plants are integrated in the management of the maizebean agroecosystem. We provide data on the chemical composition of talet beans, which is similar to that reported for other food legumes. Talet beans are recommended for development as a casually eaten protein supplement to the human diet in northern Puebla.     

A structurally unique Fusobacterium nucleatum tannase provides detoxicant activity against gallotannins and pathogen resistance

Colorectal cancer pathogenesis and progression is associated with the presence of Fusobacterium nucleatum and the reduction of acetylated derivatives of spermidine, as well as dietary components such as tannin-rich foods. We show that a new tannase orthologue of F. nucleatum (TanBF_nn) has significant structural differences with its Lactobacillus plantarum counterpart affecting the flap covering the active site and the accessibility of substrates. Crystallographic and molecular dynamics analysis revealed binding of polyamines to a small cavity that connects the active site with the bulk solvent which interact with catalytically indispensable residues. As a result, spermidine and its derivatives, particularly N⁸-acetylated spermidine, inhibit the hydrolytic activity of TanBF_nn and increase the toxicity of gallotannins to F. nucleatum. Our results support a model in which the balance between the detoxicant activity of TanBF_nn and the presence of metabolic inhibitors can dictate either conducive or unfavourable conditions for the survival of F. nucleatum.     

Sexual selection of anther trichomes and sexual dimorphism in Ibervillea lindheimeri (Cucurbitaceae: Melothrieae)

Ibervillea lindheimeri is a dioecious member of the Cucurbitaceae whose male flowers possess a number of sex-specific characteristics including eglandular trichomes on the anther connective. A 2-year study (1989 and 1990) was undertaken to assess the potential for sexual selection of anther trichome number as a male floral trait that enhances pollen removal (a male fitness component). Correlation analysis of ten reproductive and floral traits showed that only the mean number of anther trichomes per flower was significantly associated with mean pollen removal per flower. Anther trichomes are two-celled, consisting of a small, caplike, apical cell and a large, bulbous basal cell. The basal cell is under tension and produces a sticky polysaccharide that is forcefully ejected upward when the apical cell is broken off by visiting bees. The sticky polysaccharide accumulates on the bees and aids in adherence of pollen. We propose that there is directional selection on individual males for number of anther trichomes per flower. The more anther trichomes per flower, the more pollen exported, and the greater the likelihood of siring seeds. Males differed significantly in mean number of anther trichomes per flower and were relatively consistent in their rank order over a 2-year period; both are prerequisites for sexual selection to operate. Selection coefficients and differentials for 1989 and 1990 were 0.005 and 0.007, and 0.22 and 0.32, respectively, and suggest moderate to strong directional selection on anther trichome number.     

In-vitro translation of different mRNA-containing fractions of Chlamydomonas chloroplasts

Starting from isolated chloroplasts of the Chlamydomonas reinhardii cw 15 mutant, several mRNA-containing chloroplast subfractions, i.e. thylakoid-bound polysomes, detached polysomes or isolated RNA, were prepared and incubated in homologous and heterologous translation systems. In the reticulocyte lysate these fractions gave rise to strikingly different product patterns. A most prominent difference concerned the in-vivo rapidly labelled 32,000-dalton thylakoid polypeptide. Neither this membrane protein nor its 34,000-dalton precursor was formed when membrane-containing or free polysomes were translated, while the 34,000-dalton precursor was a main product of the RNA isolated from the same membranes. The influence of thylakoid membranes during translation was also observed in homologous translation systems with lysed chloroplasts supplemented with ATP. Membrane and soluble fractions, when translated separately, yielded product patterns which differed from each other, although the RNAs extracted from the respective fractions gave the same product patterns when translated in reticulocyte lysate; the latter included a soluble protein, the large subunit of ribulose-1,5-bisphosphate carboxylase, and a membrane protein, the 34,000-dalton precursor of the 32,000-dalton membrane protein, as major labelled translation products. These results point to a regulatory role of thylakoid membranes in the expression of chloroplast mRNA and argue against compartmentation of the chloroplast mRNAs between the soluble and membrane fractions.Abbreviation SDS sodium dodecyl sulfate     

Genomic cloning, chromosomal mapping, and expression analysis of Msal-2

Mutations of SALL1 related to spalt of Drosophila have been found to cause Townes-Brocks syndrome, suggesting a function of SALL1 for the development of anus, limbs, ears, and kidneys. No function is yet known for SALL2, another human spalt-like gene. The structure of SALL2 is different from SALL1 and all other vertebrate spalt-like genes described in mouse, Xenopus, and Medaka, suggesting that SALL2-like genes might also exist in other vertebrates. Consistent with this hypothesis, we isolated and characterized a SALL2 homologous mouse gene, Msal-2. In contrast to other vertebrate spalt-like genes both SALL2 and Msal-2 encode only three double zinc finger domains, the most carboxyterminal of which only distantly resembles spalt-like zinc fingers. The evolutionary conservation of SALL2/Msal-2 suggests that two lines of sal-like genes with presumably different functions arose from an early evolutionary duplication of a common ancestor gene. Msal-2 is expressed throughout embryonic development but also in adult tissues, predominantly in brain. However, the function of SALL2/Msal-2 still needs to be determined. Received: 1 June 1999 / Accepted: 26 August 1999     

The Prevalence of Obesity and Its Determinants in Urban and Rural Aging Mexican Populations

LERMAN-GARBER, ISRAEL, ANTONIO R. VILLA, CRISTINA LLACA MARTINEZ, LETICIA CERVANTES TURRUBIATEZ, CARLOS A. AGUILAR SALINAS, VILLAGRA LUCY, BELIA WONG, JUAN C. LÓPEZ ALVARENGA, FRANCISCO GÓMEZ PÉREZ, AND LUIS MIGUEL GUTIERREZ ROBLEDO. The prevalence of obesity and its determinants in urban and rural older mexican populations. Obes Res. Objective: To determine the prevalence of obesity and its association to different variables in urban and rural older Mexican populations. Methods and Procedures: A cross-sectional study of three different Mexican communities. A total of 121 men and 223 women 60 years and older and 93 men and 180 women aged 35 to 59 years old were selected randomly for inclusion in the survey. A personal interview assessed demographic information, personal medical history and functional status and a 24-hour diet recall was obtained. The physical examination included anthropometric and blood pressure measurements. A fasting blood sample was obtained for measurements of lipids, insulin and glucose. Results: Obesity was highly prevalent in women, in individuals from the urban communities and diminished with advancing age. A BMI ≥30 kg/m² was observed in 23. 6% younger vs. 15. 6% older adult men (p = 0. 21) and 28. 4% younger vs. 19. 7% older adult women (p = 0. 06). Conclusions: The present survey confirms the high prevalence of obesity in the Mexican urban population that declines with advanced age. Studies in elderly population must consider the bias produced by increased early mortality in those individuals with a more unfavorable risk profile. The association of obesity with other variables was estimated using a stepwise multivariate logistic regression, increased insulin levels [Odds Ratio (OR) 1. 68, p = 0. 006] and living in an urban area (OR 5. 90, p <0. 007) were variables independently associated to obesity in adult older individuals. In the younger adults, obesity was associated with hypertension (OR 2. 74, p<0. 0009), higher insulin levels (OR 1. 31, p<0. 03) and central adiposity (OR 2. 97, p = 0. 05), these relationship were not observed with gender, distribution of food or alcohol intake or other coronary risk factors.     

Long-term adaptive response to dietary protein of hexose monophosphate shunt dehydrogenases in rat kidney tubules

We have studied the effects of several different macronutrients on the kinetic behaviour of rat renal glucose 6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). Rats were meal-fed with high-carbohydrate/low-protein, high-protein/low-carbohydrate and high-fat diets. High-protein increased renal G6PDH and 6PDGH activities by 66 per cent and 70 per cent respectively, without significantly changing the Km values of either and each Hexose monophosphate dehydrogenase activity increased steadily, reaching a significant difference on day 4. A rise in carbohydrate or fat in the diets, produced no significant change in either the activity or the kinetic parameters, Vmax and Km of the two dehydrogenases. In addition, the administration of a high-protein diet for 8 days significantly increased both the pentose phosphate pathway flux (92.6 per cent) and the kidney weigth (35 per cent), whereas no significant changes in these parameters were found when the animals were treated with the other diets. Our results suggest that an increase in the levels of dietary protein induces a rise in the intracellular levels of these enzymes. The possible role of this metabolic pathway in the kidneys under these nutritional conditions is also discussed.     

Hypothalamic Synaptogenesis and Its Relationship with the Maturation of Hormonal Secretion

1. Information obtained during the last decade has demonstrated that hypothalamic neurons release a wide variety of neuroactive substances, such as neurotransmitters, mostly monoamines and amino acids, and neuromodulators such as the peptides vasopressin (AVP) and oxytocin (OXT) and hypophysial releasing hormones.2. Synapse formation between hypothalamic neurons was followed at different timeswithin a given nucleus and among different nuclei during development of the mouse hypo-thalamus.3. The amounts of various neurotransmitters and hormones were determined at various stages of development.4. A correlation is presented of the biochemical and ultrastructural features and theirfunctional implications during maturation.