Size and the Not-So-Single Sex: Disentangling the Effects of Size and Budget on Sex Allocation in Hermaphrodites

Sex allocation theory explains how size-related variations in male and female fitness may favor the evolution of size-dependent sex allocation in hermaphrodites. Although empirical studies show that sex allocation changes gradually with size in many species, theoretical studies tend to predict an abrupt sex reversal from one sex to the other, that is, single-sexed sequential hermaphrodites. We show that this discrepancy between data and theory collapses if one takes into account that size affects male and female fitness through distinct routes. Using the classification of budget (larger individuals spend a greater budget on reproduction) and direct (e.g., larger plants are taller and may disperse pollen more efficiently) effects of size suggested by Klinkhamer et al., we propose a simple general framework appropriately incorporating these two categories of size effects in male and female fitness expressions. Analytical and numerical results show that a gradual sex change is evolutionarily stable for a large set of parameter values. Sex reversal is selected only in the absence of budget effects of size. We provide further predictions on size-dependent sex allocation and assess the relative importance of budget and direct effect for creating different patterns

An initial study of fallow periods on the nematode community in the Soudanese-Sahelian zone of Senegal

Les observations ont été réalisées sur des jachères naturelles, sur sols ferrugineux peu profonds, dans la région de Nioro du Rip au Sud du Sénégal. Sur l'ensemble du site, 12 espèces de nématodes phytoparasites ont été identifiées. Dans les jachères anthropisées, l'effectif du peuplement ainsi que le nombre d'espèces observées diminuent lorsque l'âge de la jachère augmente de 1 à 17 ans. La mise en défens pendant 5 ans d'une jachère de 17 ans modifie ces tendances : le peuplement diminue moins vite et le nombre d'espèces est plus élevé que dans les zones anthropisées. Au plan qualitatif, seuls #Helicotylenchus dihystera et #Tylenchorhynchus gladiolatus se développent quelle que soit la situation de la jachère. Parmi les autres espèces, #Xiphinema parasetariae est plus particulièrement présent sur les jachères âgées et inversement pour #Scutellonema cavenessi. La mise en défens fait pratiquement disparaître cette espèce considérée comme très dangereuse pour les cultures de cette région. Le peuplement de nématodes saprophages reste pratiquement stable sur les jachères anthropisées. Il augmente sur la jachère en défens, notamment à proximité des ligneux. Parmi les espèces végétales, #Andropogon pseudapricus, contrairement à #Pennisetum pedicellatum, est généralement associé à des populations importantes de nématodes. (Résumé d'auteur

Dextran sulfate enhances the level of an oxidative DNA damage biomarker, 8-oxo-7,8-dihydro-2'-deoxyguanosine, in rat colonic mucosa.

International audienceDextran sodium sulfate (DSS) given in drinking water can induce colonic inflammation and produce colorectal tumors in rodents, although it is not directly genotoxic. The hypothesis that DSS can produce free radicals and induce oxidative DNA damage in colonic mucosa has been tested. In rats fed for 2 days with water containing 3% and 6% DSS, colonic inflammation manifestations were recorded and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), a major biomarker of oxidative DNA damage, was assayed in colonic mucosa. As compared with control rats given pure water, inflammatory manifestations were seen in rats given DSS. At the same time, 8-oxodGuo levels in colonic mucosa were doubled (P < 0.001). These results suggest that formation of oxidative DNA damage in colonic mucosa depends on inflammation and maybe on the production of reactive oxygen species. This study shows that DSS can induce oxidative DNA damage within only 2 days, which could explain in part its carcinogenic properties

Biologically relevant oxidants and terminology, classification and nomenclature of oxidatively generated damage to nucleobases and 2-deoxyribose in nucleic acids

A broad scientific community is involved in investigations aimed at delineating the mechanisms of formation and cellular processing of oxidatively generated damage to nucleic acids. Perhaps as a consequence of this breadth of research expertise, there are nomenclature problems for several of the oxidized bases including 8-oxo-7,8-dihydroguanine (8-oxoGua), a ubiquitous marker of almost every type of oxidative stress in cells. Efforts to standardize the nomenclature and abbreviations of the main DNA degradation products that arise from oxidative pathways are reported. Information is also provided on the main oxidative radicals, non-radical oxygen species, one-electron agents and enzymes involved in DNA degradation pathways as well in their targets and reactivity. A brief classification of oxidatively generated damage to DNA that may involve single modifications, tandem base modifications, intrastrand and interstrand cross-links together with DNA-protein cross-links and base adducts arising from the addition of lipid peroxides breakdown products is also included

Comparación entre dos tipos de gastrostomías quirúrgicas, abierta y laparoscópica, en nutrición enteral domiciliaria

Objetivo: Exponer las complicaciones de las gastrostomías quirúrgicas utilizadas como vía de soporte nutricional enteral domiciliario (SNED) y detectar si existen diferencias entre las dos técnicas usadas en nuestro medio: Cirugía abierta vs laparoscópica. Material y métodos: Estudio observacional descriptivo de carácter retrospectivo de las gastrostomías quirúrgicas realizadas entre los años 1994 y 2009 seguidas por nuestra unidad. Se han analizado las complicaciones detectadas en consulta durante el seguimiento de pacientes con SNED a través de gastrostomía quirúrgica realizada con técnica laparotómica abierta vs laparoscópica, valorando: fuga del contenido gástrico al exterior, irritación de la pared abdominal, presencia de exudado, presencia de exudado con cultivo positivo que requirió tratamiento antibiótico, quemadura o pérdida de sustancia de la zona periostomía, rotura de balón, úlcera de decúbito por la sonda y formación de granuloma. Resultados: Durante los años 1994-2009 se realizaron 57 gastrostomías quirúrgicas: 47 por técnica laparótomica (abierta) convencional y 10 por vía laparoscópica. La edad media de los pacientes fue de 57,51 ± 17,29 años. La causa más frecuente que motivó la realización de la gastrostomía quirúrgica fue el cáncer de esófago (38,6%) seguido de alteraciones neurológicas (26,3%) y tumores de cabeza y cuello (26,3%). El 97,9% de los pacientes a los que se realizó una gastrostomía quirúrgica abierta presentaron al menos una complicación, es decir que solo el 2,1% estuvieron libres de complicaciones; mientras que el 50% de los que se sometieron a una gastrostomía laparoscópica no tuvo ninguna. Las complicaciones más frecuentes fueron la presencia de fuga del contenido gástrico y la irritación de la pared abdominal que se presentaron en el 89,4% y 83% respectivamente de las gastrostomías laparotómicas frente a la aparición de solo el 30% de ambas complicaciones en las gastrostomías laparoscópicas siendo la diferencia estadísticamente significativa (p Aim: Exposing the complications of surgical gastrostomies used as way of home enteral nutritional support (HEN) and detecting the differences between the two techniques used in our environment: Open Surgery vs Laparoscopic Surgery. Material and methods: Retrospective descriptive observational study of the surgical gastrostomies performed between 1994 and 2009 followed up by our unit. Have been analyzed the complications detected in our practice during the follow-up of patients with HEN performed via open laparotomy vs. laparoscopic tecniques, assessing: leaks of gastric fluid to the exterior, abdominal wall irritation, presence of exudate, presence of exudate with positive culture that required antibiotical treatment, burning or loss of substance of the periostomic zone, breach of balloon, decubitus ulcer caused by the tube and formation of granuloma. Results: Between 1994 and 2009, 57 surgical gastrostomies were performed: 47 using the conventional laparotomic (open) tecnique and 10 laparoscopies. The average age of the patients was 57.51 ± 17.29 years old. The most common cause for the performance of surgical gastrostomy was esophageal cancer (38.6%) followed by neurologic alterations (26.3%) and head and neck tumors (26.3%). 97.9% of the patients who underwent to surgical gastrostomy presented at least one complication, meaning that only 2.1% were free of complications; meanwhile, 50% of the patients were laparoscopic gastrostomy was performed had none of these complications. The most common complications were the presence of leaks of gastric fluid and abdominal wall irritation that appeared on 89.4% and 83% respectively of the laparotomic gastrostomies versus the presence of only 30% of both complications in laparoscopic gastrostomies being the difference statistically significant (p < 0.01). Conclusions: After the introduction of the laparoscopic technique in the performance of surgical gastrostomies has been observed a decrease of the complications occured during the home enteral nutritional support related to surgical gastrostomies

Chronic methamphetamine effects on brain structure and function in rats

Methamphetamine (MA) addiction is a growing epidemic worldwide. Chronic MA use has been shown to lead to neurotoxicity in rodents and humans. Magnetic resonance imaging (MRI) studies in MA users have shown enlarged striatal volumes and positron emission tomography (PET) studies have shown decreased brain glucose metabolism (BGluM) in the striatum of detoxified MA users. The present study examines structural changes of the brain, observes microglial activation, and assesses changes in brain function, in response to chronic MA treatment. Rats were randomly split into three distinct treatment groups and treated daily for four months, via i.p. injection, with saline (controls), or low dose (LD) MA (4 mg/kg), or high dose (HD) MA (8 mg/kg). Sixteen weeks into the treatment period, rats were injected with a glucose analog, [18F] fluorodeoxyglucose (FDG), and their brains were scanned with micro-PET to assess regional BGluM. At the end of MA treatment, magnetic resonance imaging at 21T was performed on perfused rats to determine regional brain volume and in vitro [3H]PK 11195 autoradiography was performed on fresh-frozen brain tissue to measure microglia activation. When compared with controls, chronic HD MA-treated rats had enlarged striatal volumes and increases in [3H]PK 11195 binding in striatum, the nucleus accumbens, frontal cortical areas, the rhinal cortices, and the cerebellar nuclei. FDG microPET imaging showed that LD MA-treated rats had higher BGluM in insular and somatosensory cortices, face sensory nucleus of the thalamus, and brainstem reticular formation, while HD MA-treated rats had higher BGluM in primary and higher order somatosensory and the retrosplenial cortices, compared with controls. HD and LD MA-treated rats had lower BGluM in the tail of the striatum, rhinal cortex, and subiculum and HD MA also had lower BGluM in hippocampus than controls. These results corroborate clinical findings and help further examine the mechanisms behind MA-induced neurotoxicity

Use of Oral Cholera Vaccine in Haiti: A Rural Demonstration Project

A cholera epidemic has claimed the lives of more than 8,000 Haitians and sickened 650,000 since the outbreak began in October 2010. Early intervention in the epidemic focused on case-finding, treatment, and water and sanitation interventions for prevention of transmission. Use of oral cholera vaccine (OCV) as part of a complementary set of control activities was considered but initially rejected by policymakers. In December 2011, the Minister of Health of Haiti called for a demonstration of the acceptability and feasibility of the use of OCV in urban and rural Haiti. This paper describes the collaborative activity that offered OCV to one region of the Artibonite Department of rural Haiti in addition to other ongoing treatment and control measures. Despite logistics and cold chain challenges, 45,417 persons were successfully vaccinated with OCV in the region, and 90.8% of these persons completed their second dose

Derivation of consistent hard rock (1000<Vs<3000 m/s) GMPEs from surface and down-hole recordings: Analysis of KiK-net data

A key component in seismic hazard assessment is the estimation of ground motion for hard rock sites, either for applications to installations built on this site category, or as an input motion for site response computation. Empirical ground motion prediction equations (GMPEs) are the traditional basis for estimating ground motion while VS30 is the basis to account for site conditions. As current GMPEs are poorly constrained for VS30 larger than 1000 m/s, the presently used approach for estimating hazard on hard rock sites consists of “host-to-target” adjustment techniques based on VS30 and κ0 values. The present study investigates alternative methods on the basis of a KiK-net dataset corresponding to stiff and rocky sites with 500 < VS30 < 1350 m/s. The existence of sensor pairs (one at the surface and one in depth) and the availability of P- and S-wave velocity profiles allow deriving two “virtual” datasets associated to outcropping hard rock sites with VS in the range [1000, 3000] m/s with two independent corrections: 1/down-hole recordings modified from within motion to outcropping motion with a depth correction factor, 2/surface recordings deconvolved from their specific site response derived through 1D simulation. GMPEs with simple functional forms are then developed, including a VS30 site term. They lead to consistent and robust hard-rock motion estimates, which prove to be significantly lower than host-to-target adjustment predictions. The difference can reach a factor up to 3–4 beyond 5 Hz for very hard-rock, but decreases for decreasing frequency until vanishing below 2 Hz

Oxidised guanidinohydantoin (Ghox) and spiroiminodihydantoin (Sp) are major products of iron- and copper-mediated 8-oxo-7,8-dihydroguanine and 8-oxo-7,8-dihydro-2-deoxyguanosine oxidation

8-Oxo-7,8-dihydroguanine (8-oxoGua), an important biomarker of DNA damage in oxidatively generated stress, is highly reactive towards further oxidation. Much work has been carried out to investigate the oxidation products of 8-oxoGua by one-electron oxidants, singlet oxygen, and peroxynitrite. This report details for the first time, the iron- and copper-mediated Fenton oxidation of 8-oxoGua and 8-oxo-7,8-dihydro-29-deoxyguanosine (8-oxodGuo). Oxidised guanidinohydantoin (Ghox) was detected as the major product of oxidation of 8-oxoGua with iron or copper and hydrogen peroxide, both at pH 7 and pH 11. Oxaluric acid was identified as a final product of 8-oxoGua oxidation. 8-oxodGuo was subjected to oxidation under the same conditions as 8-oxoGua. However, dGhox was not generated. Instead, spiroiminodihydantoin (Sp) was detected as the major product for both iron and copper mediated oxidation at pH 7. It was proposed that the oxidation of 8-oxoGua was initiated by its one-electron oxidation by the metal species, which leads to the reactive intermediate 8-oxoGua?+, which readily undergoes further oxidation. The product of 8-oxoGua and 8-oxodGuo oxidation was determined by the 29-deoxyribose moiety of the 8-oxodGuo, not whether copper or iron was the metal involved in the oxidation