Micropropagation and in vitro conservation of wild <Emphasis Type="Italic">Arachis</Emphasis> species

Wild species of Arachis constitute potential sources of novel genes for groundnut improvement programs and some of them are also considered as new agricultural usage. The majority of these species occur in regions under intensive human activity and their areas of distribution are being drastically reduced, thus requiring effective conservation measures. Conservation of Arachis germplasm is usually carried out in seed banks or as live plants. However, seed renewal can be impaired by loss of germinative potential, and plant multiplication under field conditions can be limited by specific soil and environmental requirements or by low seed yield. Therefore, complementary in vitro methodologies represent an important tool for ex situ conservation of Arachis germplasm. In this work, we analyse the state of art of micropropagation and the use of in vitro conservation methodologies for wild relatives of the groundnut.     

Influence of operation conditions on laccase-mediator removal of sterols from eucalypt pulp

The way how sterols, the main lipophilic compounds present in eucalypt kraft pulp, are eliminated by an enzymatic stage using the laccase-mediator system was evaluated. With this purpose laccase-mediator stage (L) was applied on an Eucalyptus globulus pulp under different operation conditions following a three-variable (laccase dose, mediator dose and reaction time) sequential statistical plan, to optimise the removal of sterols. The decrease in pulp sterol content during the enzymatic treatment was related to the decrease in kappa number and to brightness increase, as well as with the increase in some oxidation products of sitosterol (namely 7-oxositosterol and stigmasta-3,5-dien-7-one). The increase in reaction time from 1 to 5 h strongly reduced the sterol content, while no more sterols were eliminated during the 5–7 h period. Increasing the laccase dose from 1 to 20 U g⁻¹ of pulp produced a high reduction in pulp sterols, whereas the increase in mediator (1-hydroxybenzotriazole) dose (from 0.5 to 2.5% of pulp weight) had only a slight influence in removing sterols. Therefore, at 16 U g⁻¹ laccase dose, 0.5% mediator dose, 4 h of reaction, practically all the sterols were removed. Finally, it was demonstrated that sterols were more sensitive to a L stage (practically 100% of sterols were eliminated) than to a chlorine dioxide stage (54% of sterols eliminated).     

MAPK phosphatase MKP2 mediates disease responses in Arabidopsis and functionally interacts with MPK3 and MPK6

Mitogen‐activated protein kinase (MAPK) cascades have important functions in plant stress responses and development and are key players in reactive oxygen species (ROS) signalling and in innate immunity. In Arabidopsis, the transmission of ROS and pathogen signalling by MAPKs involves the coordinated activation of MPK6 and MPK3; however, the specificity of their negative regulation by phosphatases is not fully known. Here, we present genetic analyses showing that MAPK phosphatase 2 (MKP2) regulates oxidative stress and pathogen defence responses and functionally interacts with MPK3 and MPK6. We show that plants lacking a functional MKP2 gene exhibit delayed wilting symptoms in response to Ralstonia solanacearum and, by contrast, acceleration of disease progression during Botrytis cinerea infection, suggesting that this phosphatase plays differential functions in biotrophic versus necrotrophic pathogen‐induced responses. MKP2 function appears to be linked to MPK3 and MPK6 regulation, as indicated by BiFC experiments showing that MKP2 associates with MPK3 and MPK6 in vivo and that in response to fungal elicitors MKP2 exerts differential affinity versus both kinases. We also found that MKP2 interacts with MPK6 in HR‐like responses triggered by fungal elicitors, suggesting that MPK3 and MPK6 are subject to differential regulation by MKP2 in this process. We propose that MKP2 is a key regulator of MPK3 and MPK6 networks controlling both abiotic and specific pathogen responses in plants.     

Cytogenetic characterization of Brazilian Paspalum accessions

Chromosome number, pairing relationship and meiotic behavior were evaluated in 24 Brazilian accessions of different Paspalum species as an initial screening to determine which of them might be useful in an interspecific hybridization program. The analysis showed that six were diploids, 16 tetraploids and two hexaploids. The pairing relationship was typical for the ploidy level and agreed with reported data. However, the meiotic behavior after diakinesis was much more abnormal than expected considering the pairing relationship. There was a high frequency of abnormal tetrads in the majority of accessions.     

Alterations in adipocytokines and cGMP homeostasis in morbid obesity patients reverse after bariatric surgery

Objective:

Obesity‐associated nonalcoholic fatty liver disease (NAFLD), covering from simple steatosis to nonalcoholic steatohepatitis (NASH), is a common cause of chronic liver disease. Aberrant production of adipocytokines seems to play a main role in most obesity‐associated disorders. Changes in adipocytokines in obesity could be mediated by alterations in cyclic GMP (cGMP) homeostasis. The aims of this work were: (1) to study the role of altered cGMP homeostasis in altered adipocytokines in morbid obesity, (2) to assess whether these alterations are different in simple steatosis or NASH, and (3) to assess whether these changes reverse in obese patients after bariatric surgery.

Design and Methods:

In 47 patients with morbid obesity and 45 control subjects, the levels in blood of adipocytokines, cGMP, nitric oxide (NO) metabolites, and atrial natriuretic peptide (ANP) were studied. Whether weight loss after a bariatric surgery reverses the changes in these parameters was evaluated.

Results:

NO metabolites and leptin increase (and adiponectin decreases) similarly in patients with steatosis or NASH, suggesting that these changes are due to morbid obesity and not to liver disease. Inflammation and cGMP homeostasis are affected both by morbid obesity and by liver disease. The increases in interleukin 6 (IL‐6), interleukin 18 (IL‐18), plasma cGMP, ANP, and the decrease in cGMP in lymphocytes are stronger in patients with NASH than with steatosis. All these changes reverse completely after bariatric surgery and weight loss, except IL‐18.

Conclusion:

Altered cGMP homeostasis seems to contribute more than inflammation to changes in leptin and adiponectin in morbid obesity.     

On the analysis of microbiological processes by Monte Carlo simulation techniques

The Barcelonagram is a Monte Carlo simulator recently designedin order to take account of the behaviour of living systems.In this paper we apply this technique to real bacterial growthin different and significant experimental conditions, namely(i) the growth of the Serratia marcescens in a minimal glucose-limitedmedium, (ii) the temperature effect on the anaerobic growthof the same strain, (iii) the growth of the Escherichia coliin a minimal medium and (iv) the normal specific growth rateof bacterial populations against the available substrate concentration.In the context of these different cases we discuss the diversecontributions of these simulated results to the understandingof the microbiological processes and the general reliabilityof the simulation considered as a third alternative besidesboth (and together with!) experience and mathematical modelling. Received on August 31, 1988; accepted on June 6, 1989     

Are fission–fusion dynamics consistent among populations? A large‐scale study with Cape buffalo

Fission–fusion dynamics allow animals to manage costs and benefits of group living by adjusting group size. The degree of intraspecific variation in fission–fusion dynamics across the geographical range is poorly known. During 2008–2016, 38 adult female Cape buffalo were equipped with GPS collars in three populations located in different protected areas (Gonarezhou National Park and Hwange National Park, Zimbabwe; Kruger National Park, South Africa) to investigate the patterns and environmental drivers of fission–fusion dynamics among populations. We estimated home range overlap and fission and fusion events between Cape buffalo dyads. We investigated the temporal dynamics of both events at daily and seasonal scales and examined the influence of habitat and distance to water on event location. Fission–fusion dynamics were generally consistent across populations: Fission and fusion periods lasted on average between less than one day and three days. However, we found seasonal differences in the underlying patterns of fission and fusion, which point out the likely influence of resource availability and distribution in time on group dynamics: During the wet season, Cape buffalo split and associated more frequently and were in the same or in a different subgroup for shorter periods. Cape buffalo subgroups were more likely to merge than to split in open areas located near water, but overall vegetation and distance to water were very poor predictors of where fission and fusion events occurred. This study is one of the first to quantify fission–fusion dynamics in a single species across several populations with a common methodology, thus robustly questioning the behavioral flexibility of fission–fusion dynamics among environments.