Gas exchange and osmotic adjustment in cotton cultivars subjected to severe salt stress.

Salinity is harmful to crops when the concentration of soluble salts overcomes the salinity threshold of the crop, causing osmotic stress and limitations in plant growth. In this scenario, adopting tolerant cultivars is the most adequate strategy to minimize agricultural losses. However, the inheritance of tolerance depends on the genotype. From this perspective, this study assessed the tolerance to severe salt stress in 11 cotton cultivars based on gas exchange parameters and the free proline content. The cultivars were grown in a greenhouse and subjected to 34 days of saline irrigation (10 dS m-1), starting 45 days after seedling emergence (B1 phase). Plant growth was monitored weekly until the end of the salt stress period. The treatments consisted of a combination of two factors: eleven cultivars associated with two electrical conductivity levels of irrigation water (ECw: 0.3 and 10.0 dS m-1). The experimental design was in randomized blocks in a 11 × 2 factorial arrangement with three replications (66 plots), with the experimental unit consisting of one plant per plot. Salinity impacted plant growth, being reflected on the gas exchange and free proline data of most cultivars. However, BRS 286, FMT 705, BRS 416, and BRS Acácia, and CNPA 7MH withstood the effects of stress and osmotically adjusted to the salt stress conditions, thus minimizing the damage to growth. Those cultivars are the most indicated for improvement programs aiming at tolerance to salt stress based on the results found in this research.

AMPA and angiotensin type 1 receptors are necessary for hemorrhage-induced vasopressin secretion.

Hypovolemia induced by hemorrhage is a common clinical complication, which stimulates vasopressin (AVP) secretion by the neurohypophysis in order to retain body water and maintain blood pressure. To evaluate the role of brain L-glutamate and angiotensin II on AVP secretion induced by hypovolemia we induced hemorrhage (∼25% of blood volume) after intracerebroventricular (icv) administration of AP5, NBQX, or losartan, which are NMDA, AMPA, and AT1 receptor antagonists, respectively. Hemorrhage significantly increased plasma AVP levels in all groups. The icv injection of AP5 did not change AVP secretion in response to hemorrhage. Conversely, icv administration of both NBQX and losartan significantly decreased plasma AVP levels after hemorrhage. Therefore, the blockade of AMPA and AT1 receptors impaired AVP secretion in response to hemorrhage, suggesting that L-glutamate and angiotensin II acted in these receptors to increase AVP secretion in response to hemorrhage-induced hypovolemia.

AMPA and angiotensin type 1 receptors are necessary for hemorrhage-induced vasopressin secretion

Hypovolemia induced by hemorrhage is a common clinical complication, which stimulates vasopressin (AVP) secretion by the neurohypophysis in order to retain body water and maintain blood pressure. To evaluate the role of brain L-glutamate and angiotensin II on AVP secretion induced by hypovolemia we induced hemorrhage (∼25% of blood volume) after intracerebroventricular (icv) administration of AP5, NBQX, or losartan, which are NMDA, AMPA, and AT1 receptor antagonists, respectively. Hemorrhage significantly increased plasma AVP levels in all groups. The icv injection of AP5 did not change AVP secretion in response to hemorrhage. Conversely, icv administration of both NBQX and losartan significantly decreased plasma AVP levels after hemorrhage. Therefore, the blockade of AMPA and AT1 receptors impaired AVP secretion in response to hemorrhage, suggesting that L-glutamate and angiotensin II acted in these receptors to increase AVP secretion in response to hemorrhage-induced hypovolemia.

Acute body sodium depletion induces skin sodium mobilization in female Wistar rats.

NEW FINDINGS: What is the central question of this study? Can Na+ depletion mobilize Na+ from the skin reservoir in ovariectomized rats? Does oestrogen replacement change the amount and the dynamics of skin Na+ storage? Is the reduced salt appetite after Na+ depletion in ovariectomized rats with oestrogen replacement related to changes in the skin Na+ ? What is the main finding and its importance? This work demonstrated that acute body Na+ depletion induced by frusemide mobilized the osmotically inactive skin Na+ reservoir to become osmotically active. Oestrogen treatment decreased the induced Na+ intake in ovariectomized rats but did not modulate the inactive Na+ reservoir in control conditions or its mobilization induced by Na+ depletion. ABSTRACT: Oestradiol, which is an important hormone for water and electrolyte balance, also has a role in the inhibition of induced Na+ appetite. Sodium can be stored in the skin in osmotically active or inactive forms, and this skin Na+ reservoir may be involved in the control of body Na+ levels during physiopathological challenges. In this study, we investigated whether the effect of sodium depletion by frusemide can mobilize Na+ from the skin reservoir and whether oestradiol replacement changes or mobilizes the Na+ reserves in the skin. Ovariectomized Wistar rats were treated with vehicle or oestradiol for 7 days to evaluate the effects of oestrogen on the hydroelectrolyte balance, intake responses and skin Na+ and water content in basal conditions. Furthermore, the effects of oestrogen were evaluated after 24 h frusemide-induced whole-body Na+ depletion. Oestradiol-replaced rats exhibited reduced water intake without any significant changes in salt intake, Na+ excretion or water and Na+ skin content in basal conditions. After sodium depletion, both vehicle- and oestradiol-treated rats exhibited an increase in the osmotically active skin Na+ , which was associated with a decrease of the inactive skin Na+ reservoir. Oestrogen decreased the hypertonic saline intake induced by Na+ depletion, but it was not associated with any significant changes in the skin Na+ reservoir. Thus, sodium depletion is able to change the inactive-active skin Na+ reservoir balance. However, the oestrogenic modulation of sodium appetite after Na+ depletion is probably not related to the action of this hormone in the skin Na+ reservoir balance.

Alterations in hypothalamic synaptophysin and death markers may be associated with vasopressin impairment in sepsis survivor rats.

The impairment in arginine vasopressin (AVP) secretion during sepsis is described in clinical and experimental studies and has been associated with oxidative stress, apoptosis, and diminished activation of hypothalamic neurons. Few studies have, however, assessed these abnormalities in sepsis survivors. Here we performed two sets of experiments on Wistar rats that had been subjected to sepsis by cecal ligation and puncture (CLP) or nonmanipulated (naive) as control. In the first set, tissues and blood were collected from survivor rats 10 days after CLP to quantify hypothalamic Bcl-2, cleaved caspase- 3 and synaptophysin content, and bacterial load. In the second set, survivor rats were submitted to an acute osmotic stimulus (hypertonic saline), and after 30 minutes the water intake and AVP secretion were analyzed. The sepsis-surviving rats did not show bacterial load in tissues, but their hypothalamic synaptophysin and Bcl-2 levels were decreased, and the cleaved caspase- 3 level was increased when compared with the control group. However, AVP secretion was significantly attenuated in the CLP survivor animals submitted to an acute osmotic stimulus. These results suggest that the persistent AVP impairment in sepsis survivor animals may be due to a hypothalamic dysfunction associated with a synaptic deficit and decreased anti-apoptotic protein expression. This article is protected by copyright. All rights reserved.

Effects of autonomic balance and fluid and electrolyte changes on cardiac function in infarcted rats: A serial study of sexual dimorphism.

Premenopausal women are known to show lower incidence of cardiovascular disease than men. During myocardial infarction (MI), homeostatic responses are activated, including the sympathetic autonomic nervous system and the rennin-angiotensin-aldosterone system, which is related to the fluid and electrolyte balance, both aiming to maintain cardiac output. This study sought to perform a serial evaluation of sexual dimorphism in cardiac autonomic control and fluid and electrolyte balance during the development of MI-induced heart failure in rats. Experimental MI was induced in male (M) and female (F) adult (7-9 weeks of age) Wistar rats. The animals were placed in metabolic cages to assess fluid intake and urine volume 1 and 4 weeks after inducing MI (male myocardial infarction (MMI) and female myocardial infarction (FMI) groups). They subsequently underwent echocardiographic evaluation and spectral analysis of heart rate variability. After completing each protocol, the animals were killed for postmortem evaluation and histology. The MMI group showed earlier and more intense cardiac morphological and functional changes than the FMI group, although the extent of MI did not differ between groups (P > 0.05). The MMI group showed higher sympathetic modulation and sodium and water retention than the FMI group (P < 0.05), which may partly explain both the echocardiographic and pathological findings. Females subjected to infarction seem to show attenuation of sympathetic modulation, more favourable fluid and electrolyte balances, and better preserved cardiac function compared to males subjected to the same infarction model.

Clastogenic effect of bracken fern (Pteridium aquilinum v. arachnoideum) diet in peripheral lymphocytes of human consumers: preliminary data.

Ingestion of bracken fern (Pteridium aquilinum v. arachnoideum) is associated with digestive tract cancer in different regions of Japan, Venezuela and Brazil. In view of reports that dietary bracken fern causes chromosomal instability in cattle, the clastogenic effect of bracken fern was investigated, in a preliminary study, in peripheral lymphocytes obtained from habitual consumers and a control group of non-consumers, which were carefully investigated about cancer history or family cancer history, negative in both cases, using protocols comparable to those previously described in studies in cattle raised on bracken pastures. Cytogenetic analysis showed significant increased levels of chromosomal abnormalities, such as chromatid breaks, in cultured peripheral lymphocytes of the consumer group. There was no correlation with subjects, gender, smoking habits or alcohol consumption, and the only correlation was with prolonged exposure to dietary bracken.

Quercetin induces structural chromosomal aberrations and uncommon rearrangements in bovine cells transformed by the E7 protein of bovine papillomavirus type 4.

Bovine papillomavirus type 4 (BPV-4) and bracken fern are cofactors in the carcinogenesis of the upper gastrointestinal (GI) tract of cattle. An experimental in vitro model system has been developed to analyse the co-operation between the viral transforming protein E7, the cellular ras oncogene and quercetin, one of the mutagens of bracken fern, during neoplastic progression of primary bovine cells. We now report cytogenetic studies of these cells at different stages of malignant transformation: parental primary non-transformed PalF cells; E7R cells transformed by BPV-4 E7 and activated ras but not tumorigenic, and tumorigenic E7Q cells derived from E7R cells after treatment with quercetin. All cell lines presented increased numbers of aneuploid cells. The rate of structural chromosomal aberrations observed was increased in transformed cells. In addition, E7Q cells showed chromosomes with peculiar rearrangements, which resulted in metacentric and submetacentric marker chromosomes, with an increase in the mean chromosome arm number. These markers were the products of possible centric fusions. These aberrations and rearrangements were distributed throughout the karyotype, no specific chromosome was involved and the heterochromatic centromeric regions appeared to be preserved.

[The synanthropic potential of Kerteszia and Culex mosquitoes (Diptera:Culicidae) in Southeastern Brazil]. / Potencial sinantrópico de mosquitos Kerteszia e Culex (Diptera: Culicidae) no Sudeste do Brasil.

OBJECTIVE: To determine the synanthropic potential of Anopheles bellator and An. cruzii in a village close to a wild environment. For comparative purposes, Culex quinquefasciatus and Cx. sacchettae populations were also investigated. METHODS: From October 1996 to January 2000, vectors investigations were carried out in Pedrinhas village, Southeastern of S. Paulo State, Brazil, through systematic collections with human bait, air aspirations and Shannon traps. The synanthropic index was estimated using Nuorteva's indices plus the Mihályi's endophylic factor. RESULTS: Attraction principle was s=35.7 for both Kerteszia species at the peridomiciliary environment through human bait. Cx. sacchettae showed a sr ratio of 12.8 with a degree of synanthropy. However active search through the aspiration method yielded negative s values, such as -43.1 for An. bellator and -48.2 for An. cruzii. For Cx. sacchettae that value was -3.0. These values were calculated when +100.00 was given to Cx. quinquefasciatus, which showed the highest synanthropic habits, corresponding to s =+93.8. CONCLUSIONS: The present data allow to conclude that what was observed until now for isolated rural dwellings is valid for small villages at the same conditions. This means that female Kerteszia adults tend to be in anthropic environment for blood seeking. After that, they return to the surrounding natural environment of the village. Regarding Cx. Sacchettae, they seem to have an anthropic adaptation tendency.

Bovine papillomavirus transmission and chromosomal aberrations: an experimental model.

Enzootic haematuria and urinary bladder cancer in cattle are associated with feeding on bracken fern and bovine papillomavirus (BPV) infection. An increased rate of chromosomal aberrations in peripheral blood lymphocytes from chronically affected haematuric cows raised in bracken fern pastures has been reported, suggesting the presence of BPV in the peripheral blood of afflicted animals. The purpose of the present investigation was to examine the role of peripheral blood as a potential BPV-transmitting agent and search for clastogenic effects in experimentally infected animals kept on a bracken fern-free diet. Healthy cows were inoculated with blood samples of haematuric animals every two weeks for 18 months. Recipient cows, their offspring, donor animals and a control group were kept on a bracken fern-free diet throughout the experiment. Clinical and molecular analyses for detection of BPV infection were carried out periodically in all groups. Short-term lymphocyte cultures were performed to assess chromosomal aberration levels. The donor cows, the recipient cows and their offspring presented increased levels of chromosomal aberrations. BPV-2 DNA was identified by Southern blotting, PCR and cycle-sequencing of PCR products in peripheral blood of donor and recipient animals and in the progeny of recipient animals. Data support both the concept that BPV can be transmitted through blood and the hypothesis that infection with the virus causes the clastogenic alterations observed in the present experimental model. The presence of BPV-2 DNA and chromosomal alterations in peripheral blood of offspring at the moment of birth is evidence for vertical transmission of BPV.

Intoxication by Xanthium cavanillesii in cattle and sheep in southern Brazil.

Three outbreaks of Xanthium cavanillesii intoxication occurred in the spring in the State of Rio Grande do Sul, southern Brazil. All outbreaks were observed in paddocks with sandy soils in flood plains along water streams. The paddocks had been under water, and after water withdrawal cattle were introduced to those areas which had seedlings of X cavanillesii and shortage of other forage. Mortality varied between 3 and 58%. Most animals were found dead or died a few hours after observation of clinical signs. The main lesion was a swollen liver with acute diffuse centrilobular necrosis. The disease was produced experimentally by feeding cotyledons at 0.75 and 1% bw in calves, and at 1.5 and 2% bw in sheep. Clinical signs and gross and microscopic lesions were similar to those observed in field cases. X cavanillesii in the 4-leaf stage with the attached cotyledons was also toxic for cattle and sheep, but the same plant without cotyledons lost its liver toxicity. The lethal dose of cotyledons divided in 5 daily doses was not toxic for cattle and sheep, demonstrating the non-cumulative effect of the plant.

[Biliary atresia - study of 19 patients]. / Atresia de vias biliares - Estudo de 19 casos.

This is a retrospective analysis of 19 babies born with biliary atresia (12 girls, 7 boys) who were treated at the Hospital das Clínicas of the Ribeirão Preto Medicine School. The portoenterostomy operation was performed in 16 patients. All operations were performed before 12 weeks of postnatal life. Diagnostic laboratory studies are discussed. The authors conclude that the cholestatic jaundice protocol employed proved to be very necessary, can lead to early diagnosis can improve survival.

X-linked syndrome: mental retardation, hip luxation, and G6PD variant [Gd(+) Butantan].

An apparently new X-linked syndrome is presented. It occurred in four male first cousins. The main manifestations of this syndrome are severe mental retardation, bilateral congenital hip luxation, and short stature. Three of the affected males showed a new glucose-6-phosphate dehydrogenase variant.

Chromosome aberrations in cattle raised on bracken fern pasture.

Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.