Molecular Basis for Resistance to Fluazifop-P-Butyl in Itchgrass (Rottboellia cochinchinensis) from Costa Rica

Rottboellia cochinchinensis is an annual grass weed species known as itchgrass, or "caminadora" in America´s Spanish speaking countries, and has become a major and troublesome weed in several crops. The application of fluazifop-P-butyl at recommended rates (125 g a.i. ha-1) was observed to be failing to control itchgrass in a field in San José, Upala county, Alajuela province, Costa Rica. Plants from the putative resistant R. cochinchinensis population survived fluazifop-P-butyl when treated with 250 g a.i. ha-1 (2X label rate) at the three- to four-leaf stage under greenhouse conditions. PCR amplification and sequencing of partial carboxyl transferase domain (CT) of the acetyl-CoA carboxylase (ACCase) gene were used to determine the molecular mechanism of resistance. A single non-synonymous point mutation from TGG (susceptible plants) to TGC (putative resistant plants) that leads to a Trp-2027-Cys substitution was found. This Trp-2027-Cys mutation is known to confer resistance to all aryloxyphenoxyproprionate (APP) herbicides to which fluazifop-P-butyl belongs. To the best of our knowledge, this is the first report of fluazifop-P-butyl resistance and a mutation at position 2027 for a Costa Rican R. cochinchinensis population.

One-winged Drosophila subobscura: a phenotype with an obscure genetic basis

A line of one-winged Drosophila subobscura was studied. The absent wing is substituted by a bulky structure with macro and microchaetes, showing a thoracic appearance. Genetic crosses showed that there is no way to select for the trait by simple crossing. The number of one-winged flies in the various generations was always low. In one case a wingless fly was also obtained. The trait presents an unknown genetic pattern.

The yellow fever 17D vaccine virus: molecular basis of viral attenuation and its use as an expression vector

The yellow fever (YF) virus is the prototype flavivirus. The use of molecular techniques has unraveled the basic mechanisms of viral genome structure and expression. Recent trends in flavivirus research include the use of infectious clone technology with which it is possible to recover virus from cloned cDNA. Using this technique, mutations can be introduced at any point of the viral genome and their resulting effect on virus phenotype can be assessed. This approach has opened new possibilities to study several biological viral features with special emphasis on the issue of virulence/attenuation of the YF virus. The feasibility of using YF virus 17D vaccine strain, for which infectious cDNA is available, as a vector for the expression of heterologous antigens is reviewed

Myocyte necrosis is the basis for fibrosis in renovascular hypertensive rats

The pathogenesis of fibrosis and the functional features of pressure overload myocardial hypertrophy are still controversial. The objectives of the present study were to evaluate the function and morphology of the hypertrophied myocardium in renovascular hypertensive (RHT) rats. Male Wistar rats were sacrificed at week 4 (RHT4) and 8 (RHT8) after unilateral renal ischemia (Goldblatt II hypertension model). Normotensive rats were used as controls. Myocardial function was analyzed in isolated papillary muscle preparations, morphological features were defined by light microscopy, and myocardial hydroxyproline concentration (HOP) was determined by spectrophotometry. Renal artery clipping resulted in elevated systolic arterial pressure (RHT4: 178 ± 19 mmHg and RHT8: 194 ± 24 mmHg, P<0.05 vs control: 123 ± 7 mmHg). Myocardial hypertrophy was observed in both renovascular hypertensive groups. The myocardial HOP concentration was increased in the RHT8 group (control: 2.93 ± 0.38 µg/mg; RHT4: 3.02 ± 0.40 µg/mg; RHT8: 3.44 ± 0.45 µg/mg of dry tissue, P<0.05 vs control and RHT4 groups). The morphological study demonstrated myocyte necrosis, vascular damage and cellular inflammatory response throughout the experimental period. The increased cellularity was more intense in the adventitia of the arterioles. As a consequence of myocyte necrosis, there was an early, local, conjunctive stroma collapse with disarray and thickening of the argyrophilic interstitial fibers, followed by scarring. The functional data showed an increased passive myocardial stiffness in the RHT4 group. We conclude that renovascular hypertension induces myocyte and arteriole necrosis. Reparative fibrosis occurred as a consequence of the inflammatory response to necrosis. The mechanical behavior of the isolated papillary muscle was normal, except for an early increased myocardial passive stiffness

Structural basis for the pathophysiology of lipoprotein(a) in the athero-thrombotic process

Lipoprotein Lp(a) is a major and independent genetic risk factor for atherosclerosis and cardiovascular disease. The essential difference between Lp(a) and low density lipoproteins (LDL) is apolipoprotein apo(a), a glycoprotein structurally similar to plasminogen, the precursor of plasmin, the fibrinolytic enzyme. This structural homology endows Lp(a) with the capacity to bind to fibrin and to membrane proteins of endothelial cells and monocytes, and thereby to inhibit plasminogen binding and plasmin generation. The inhibition of plasmin generation and the accumulation of Lp(a) on the surface of fibrin and cell membranes favor fibrin and cholesterol deposition at sites of vascular injury. Moreover, insufficient activation of TGF-ß due to low plasmin activity may result in migration and proliferation of smooth muscle cells into the vascular intima. These mechanisms may constitute the basis of the athero-thrombogenic mode of action of Lp(a). It is currently accepted that this effect of Lp(a) is linked to its concentration in plasma. An inverse relationship between Lp(a) concentration and apo(a) isoform size, which is under genetic control, has been documented. Recently, it has been shown that inhibition of plasminogen binding to fibrin by apo(a) is also inversely associated with isoform size. Specific point mutations may also affect the lysine-binding function of apo(a). These results support the existence of functional heterogeneity in apolipoprotein(a) isoforms and suggest that the predictive value of Lp(a) as a risk factor for vascular occlusive disease would depend on the relative concentration of the isoform with the highest affinity for fibrin

The molecular basis of selective permeability of connexins is complex and includes both size and charge

Although gap junction channels are still widely viewed as large, non-specific pores connecting cells, the diversity in the connexin family has led more attention to be focused on their permeability characteristics. We summarize here the current status of these investigations, both published and on-going, that reveal both charge and size selectivity between gap junction channels composed of different connexins. In particular, this review will focus on quantitative approaches that monitor the expression level of the connexins, so that it is clear that differences that are seen can be attributed to channel properties. The degree of selectivity that is observed is modest compared to other channels, but is likely to be significant for biological molecules that are labile within the cell. Of particular relevance to the in vivo function of gap junctions, recent studies are summarized that demonstrate that the connexin phenotype can control the nature of the endogenous traffic between cells, with consequent effects on biological effects of gap junctions such as tumor suppression.

The brain decade in debate: II. Panic or anxiety? From animal models to a neurobiological basis

This article is a transcription of an electronic symposium sponsored by the Brazilian Society of Neuroscience and Behavior (SBNeC). Invited researchers from the European Union, North America and Brazil discussed two issues on anxiety, namely whether panic is a very intense anxiety or something else, and what aspects of clinical anxiety are reproduced by animal models. Concerning the first issue, most participants agreed that generalized anxiety and panic disorder are different on the basis of clinical manifestations, drug response and animal models. Also, underlying brain structures, neurotransmitter modulation and hormonal changes seem to involve important differences. It is also common knowledge that existing animal models generate different types of fear/anxiety. A challenge for future research is to establish a good correlation between animal models and nosological classification.

Immunological basis of septal fibrosis of the liver in Capillaria hepatica-infected rats

Rats infected with the helminth Capillaria hepatica regularly develop septal fibrosis of the liver similar to that induced by repeated ip injections of pig serum. Fibrosis starts when the focal parasitic lesions begin to show signs of resorption, thus suggesting an immunologically mediated pathogenesis of this fibrosis. To explore this possibility, the development of C. hepatica-related hepatic fibrosis was observed in rats exposed to worm antigens from the first neonatal day onward. Wistar rats (150 g) were either injected ip with an extract of C. hepatica eggs (protein concentration: 1 mg/ml) or received immature eggs by gavage from the first neonatal day until adult life and were then infected with 500 embryonated eggs. Changes were monitored on the basis of serum levels of anti-worm antibodies and hepatic histopathology. Rats submitted to immunological oral tolerance markedly suppressed C. hepatica-related serum antibodies and septal fibrosis of the liver when infected with the helminth later on. Tolerance trials with ip injections of worm antigens gave essentially negative results. The partial suppression of septal fibrosis of the liver after the induction of immunological tolerance to C. hepatica antigens in rats indicates an immunological basis for the fibrosis and emphasizes the importance of immunological factors in the pathogenesis of hepatic fibrosis.

Collective Memory Embodied in Poetry as Poison. The Mnemonic Role of Romantic Poets Discussed on the Basis of Adam Mickiewicz’ Konrad Wallenrod and Forefathers (Part III)

This thesis constitutes an interdisciplinary approach to the Polish Romanticism combining literature studies with memory studies, nationalism research and psychoanalysis. This phenomenon-based study attempts to answer the question, how the Polish national poet Adam Mickiewicz (1798–1855) – or more exactly the implied authors in his works – perceived the role of poetry in mnemonic terms and how it changes in course of time. Consequently, ‘memory in literature’ (Astrin Erll and Ansger Nünning) is discussed here. Two pieces of writing by Mickiewicz – Konrad Wallenrod [1828] and the third part of Forefathers [1832], where a bard respectively a poetic genius appears – are seen as meta-texts defining goals of poets in time of the political non-existence of a state. Poetry is supposed to keep memory of the glorious past alive, kindle the love for the motherland, support the collective identity of a group and initiate a liberation movement. Poets function as memory guards, leaders of the nation and prophets. Thus, literature is a medium of collective memory – it stores crucial contents, transmits them and acts as a cue. Nevertheless, shifting the focus from the community towards well-being of individuals, which is consistent with the postmodern thinking, the impact that poetry has on members of a given memory culture (Jan Assmann) can be described in ‘vampiric’ terms (Maria Janion). Poetry embodying collective memory may be compared to ‘poison’, ‘infecting’ people with a nationalistic way of thinking to their disadvantage as far as their personal lives are concerned.

Comparison of scientists of the Brazilian Academy of Sciences and of the National Academy of Sciences of the USA on the basis of the h-index

A new scientometric indicator, the h-index, has been recently proposed (Hirsch JE. Proc Natl Acad Sci 2005; 102: 16569-16572). The index avoids some shortcomings of the calculation of the total number of citations as a parameter to evaluate scientific performance. Although it has become known only recently, it has had widespread acceptance. A comparison of the average h-index of members of the Brazilian Academy of Sciences (BAS) and of the National Academy of Sciences of the USA (NAS-USA) was carried out for 10 different areas of science. Although, as expected, the comparison was unfavorable to the members of the BAS, the imbalance was distinct in different areas. Since these two academies represent, to a significant extent, the science of top quality produced in each country, the comparison allows the identification of the areas in Brazil that are closer to the international stakeholders of scientific excellence. The areas of Physics and Mathematics stand out in this context. The heterogeneity of the h-index in the different areas, estimated by the median dispersion of the index, is significantly higher in the BAS than in the NAS-USA. No elements have been collected in the present study to provide an explanation for this fact.

Drugs and lifestyle for the treatment and prevention of coronary artery disease: comparative analysis of the scientific basis

In this article, we compare two strategies for atherosclerosis treatment: drugs and healthy lifestyle. Statins are the principal drugs used for the treatment of atherosclerosis. Several secondary prevention studies have demonstrated that statins can significantly reduce cardiovascular events including coronary death, the need for surgical revascularization, stroke, total mortality, as well as fatal and non-fatal myocardial infarction. These results were observed in both men and women, the elderly, smokers and non-smokers, diabetics and hypertensives. Primary prevention studies yielded similar results, although total mortality was not affected. Statins also induce atheroma regression and do not cause cancer. However, many unresolved issues remain, such as partial risk reduction, costs, several potential side effects, and long-term use by young patients. Statins act mainly as lipid-lowering drugs but pleiotropic actions are also present. Healthy lifestyle, on the other hand, is effective and inexpensive and has no harmful effects. Five items are associated with lower cardiac risk: non-smoking, BMI ≤25, regular exercise (30 min/day), healthy diet (fruits, vegetables, low-saturated fat, and 5-30 g alcohol/day). Nevertheless, there are difficulties in implementing these measures both at the individual and population levels. Changes in behavior require multidisciplinary care, including medical, nutritional, and psychological counseling. Participation of the entire society is required for such implementation, i.e., universities, schools, media, government, and medical societies. Although these efforts represent a major challenge, such a task must be faced in order to halt the atherosclerosis epidemic that threatens the world.