Collagen and Microvascularization in Placentas From Young and Older Mares.

In older mares, increasing collagen fibers (fibrosis) in the endometrium and oviduct predisposes to sub-fertility and infertility. In this study, (i) gene transcription of collagen (qPCR: COL1A1, COL1A2, COL3A1, COL5A1); (ii) total collagen protein (hydroxyproline); (iii) collagen distribution (Picrosirius red staining; polarized light microscopy); and (iv) microvascular density (Periodic acid-Schiff staining), were evaluated in mares' placenta, and related to mares age, and placenta and neonate weights. Samples were collected from the gravid horn, non-gravid horn, and body of the placenta from younger (n = 7), and older mares (n = 9) of different breeds. Transcripts of COL1A1, COL3A1 and COL5A1, total collagen protein, chorionic plate connective tissue thickness, and microvascularization increased in the gravid horn of older mares' placentas, compared to the youngest (P < 0.05). Although in other species placenta fibrosis may indicate placental insufficiency and reduced neonate weight, this was not observed here. It appears that older fertile mares, with more parities, may develop a heavier, more vascularized functional placenta with more collagen, throughout a longer gestation, which enables the delivery of heavier foals. Thus, these features might represent morphological and physiological adaptations of older fertile mares' placentas to provide the appropriate nutrition to the equine fetus.

An update on three radiation accidents in South America.

This paper revisits three major accidents that occurred in South America. The main purpose of this review is to analyze the long term health and other effects of accidental exposures to ionizing radiation in order to extract lessons from these radiological emergencies that might be useful for avoiding similar events (primary prevention) and for preparing the overall response to radiation accidents to mitigate their different impacts (secondary prevention). For that, consults were made on the pertinent literature and use was made of personal information of the authors.

Tolerância de leguminosas de cobertura do solo a Herbicidas

There is little research regarding to tolerance of soil cover legumes to herbicides. Products that are selective to these plants and show satisfactory control of harmful plants are still scarce. This paper has the objective to evaluate the tolerance to herbicide of four legume plants. The experiment was installed in a greenhouse. The four legumes were sowed in a 2 kg plastic bag. The substratum was homogenized with two seeds of Pueraria phaseoloides, Desmodium ovalifolium, Mucuna aterrima and Mucuna cochinchinensis. The herbicides applied were 2,4-DB, in post-emergence and alachlor, imazaquin and pendimethalin in pre-emergence. The statistical experimental method used was completely randomized in a factorial experiment (4x4x5x4) with four legume species, four herbicides and five doses of each herbicide with four replications. Thirty six days after sowing, P. phaseoloides showed tolerance to the herbicides alachlor and imazaquin and susceptibility to 2,4-DB and pendimethalin. D. ovalifolium was susceptible to herbicides except the alachlor. M. aterrima showed tolerance to alachlor, imazaquin and pendimethalin and was susceptible to 2,4-DB. The herbicides alachlor and imazaquin were not phytotoxic to M. cochinchinensis. However, severe injury was observed with the use of 2,4-DB and pendimethalin.

São poucas as pesquisas de tolerância de leguminosas de cobertura do solo a herbicidas visando selecionar produtos que sejam seletivos a estas plantas e que apresentem controle satisfatório das plantas daninhas. Com o objetivo avaliar a tolerância de quatro leguminosas a herbicidas, instalou-se um experimento em condições de casa-de-vegetação. As leguminosas foram plantadas em sacos plásticos de dois litros, contendo substrato homogeneizado com duas sementes das leguminosas Pueraria phaseoloides, Desmodium ovalifolium, Mucuna aterrima e Mucuna cochinchinensis. Os herbicidas aplicados foram 2,4-DB, em pós-emergência, e alachlor, imazaquin e pendimethalin em pré-emergência. O delineamento experimental foi inteiramente ao acaso, em esquema fatorial de 4x4x5x4 com quatro espécies de leguminosas, quatro herbicidas e cinco doses de cada herbicida, respectivamente, repetidos quatro vezes. Aos trinta e seis dias após o plantio a Pueraria phaseoloides mostrou-se tolerante aos herbicidas alachlor e imazaquin e suscetível ao 2,4-DB e pendimethalin. O Desmodium ovalifolium foi suscetível aos herbicidas nas doses usadas, exceto o alachlor. A Mucuna aterrima apresentou tolerância ao alachlor, imazaquin e pendimethalin e foi suscetível ao 2,4-DB. Os herbicidas alachlor e imazaquin não foram fítotóxicos à Mucuna cochinchinensis, enquanto 2,4-DB e pendimethalin causaram severas injúrias.