Constraints on tree seedling establishment after fires: passing the germination bottlenecks

Persistence and colonization by tree species in an environment following a fire depends on the effects on seed germination and seedling development. We used seeds of Kielmeyera coriacea and Qualea parviflora as a model to test the effects of high temperatures on germination and initial development of tree seedlings. We exposed the seeds to heat flow (70, 100, 130, 150 or 170 °C) for 2 or 5 min and compared the germination with that of unheated seeds (control). Seedlings were then harvested after 3, 7 or 15 days to evaluate aerial and root mass, root:shoot ratio, presence of cotyledon opening, true leaves, and secondary roots. We found no effect on germination for seeds exposed to temperatures ≥150 °C. However, germination was significantly reduced for seeds exposed to 100 °C for both 2 and 5 min. The mass of 15-day-old K. coriacea seedlings was smaller when seeds were heated at 70 °C for 5 min or at temperatures higher or equal to 100 °C. Qualea parviflora seedlings did not show any difference in mass, but there were marginal differences in the presence of roots and the opening of cotyledons. Kielmeyera coriacea seedlings allocated biomass faster than Q. parviflora. High temperatures affect both quantity and quality of germinable seeds, as well as biomass allocation during initial seedling development. These factors may explain the decrease in seedlings observed after fire, suggesting a bottleneck effect that influences population dynamics and species persistence in systems with frequent fires.

Complete sequence of a new bipartite begomovirus infecting Sida sp. in Northeastern Brazil

In Brazil, non-cultivated plants, especially weeds, are infected with a diversity of begomoviruses and often show striking golden mosaic symptoms. In the present study, leaves showing these symptoms were collected from Sida sp. plants in Guadalupe, Piaui State, Northeastern Brazil, in 2015 and 2016. PCR tests with degenerate primers revealed the presence of begomovirus DNA-A and DNA-B components. Restriction enzyme digestion of rolling circle-amplified DNA revealed fragments totaling ~5.2 kb, indicating infection by a bipartite begomovirus. The DNA-A and DNA-B components have a genome organization typical of New World (NW) bipartite begomoviruses and a common region of 220 nucleotides (nt) with 96% identity, indicating these are cognate components. Comparisons performed with the DNA-A sequence revealed the highest nt sequence identity (84%) with that of sida angular mosaic virus (SiAMV), whereas those performed with the DNA-B sequence revealed highest identity (77%) with that of sida chlorotic vein virus (SiCVV). In phylogenetic analyses, the DNA-A sequence was placed in a strongly supported clade with SiAMV and SiCVV from Piaui, whereas the DNA-B sequence was placed in a clade with SiCVV and corchorus mottle virus. Based on the current ICTV criteria for the demarcation of begomovirus species (<91% nt sequence identity for the DNA-A component), this is a member of a new species for which the name "Sida yellow golden mosaic virus" is proposed.

World Management of Geminiviruses

Management of geminiviruses is a worldwide challenge because of the widespread distribution of economically important diseases caused by these viruses. Regardless of the type of agriculture, management is most effective with an integrated pest management (IPM) approach that involves measures before, during, and after the growing season. This includes starting with resistant cultivars and virus- and vector-free transplants and propagative plants. For high value vegetables, protected culture (e.g., greenhouses and screenhouses) allows for effective management but is limited owing to high cost. Protection of young plants in open fields is provided by row covers, but other measures are typically required. Measures that are used for crops in open fields include roguing infected plants and insect vector management. Application of insecticide to manage vectors (whiteflies and leafhoppers) is the most widely used measure but can cause undesirable environmental and human health issues. For annual crops, these measures can be more effective when combined with host-free periods of two to three months. Finally, given the great diversity of the viruses, their insect vectors, and the crops affected, IPM approaches need to be based on the biology and ecology of the virus and vector and the crop production system. Here, we present the general measures that can be used in an IPM program for geminivirus diseases, specific case studies, and future challenges.

PP166. HELLP syndrome: Challenges for establishing diagnostic criteria

INTRODUCTION

Preeclampsia is a public health problem which may manifest as pre-eclampsia (hypertension, proteinuria and/or edema) and eclampsia (convulsive crises and rarely coma in pregnant women with previous pre-eclampsia). But the pathology of hypertensive disease of pregnancy can present different clinical forms. Within that spectrum is HELLP syndrome: hemolysis (H), elevated liver enzymes (EL) and thrombocytopenia (LP).

OBJECTIVES

To assess the diagnostic criteria in the literature adopted for HELLP syndrome.

METHODS

A literature review on the Virtual Health Library with the keywords "HELLP syndrome" and "diagnosis" found 674 citations. Six hundred and thirty-four dismissed for failing to engage with the proposed question, and 43 articles remained. Twenty seven articles were excluded because of the language, unable in Latin America, letters, case report and articles published prior to 1999. Sixteen original articles were included. Eleven reviews, one prospective study, two cohorts, one retrospective cohort study and a cross. Studies were classified according to degree of recommendation and level of evidence.

RESULTS

The term clinical and laboratory markers were varied and their cut-off levels differ among the authors. The appearance of eclampsia, pain in the upper abdomen, nausea and significant proteinuria and other maternal morbidities were more frequent in patients with HELLP syndrome. The levels of lactic dehydrogenase, AST, and uric acid were further elevated in women with HELLP syndrome guarding correlation with the prognosis of the case. There is no consensus for the interpretation of laboratory values that may represent the most widespread occurrence of parameters: hemolytic anemia, elevated liver enzymes and thrombocytopenia. Other morbidities may have clinical signs, symptoms and laboratory abnormalities that mimic the syndrome.

CONCLUSION

There are many questions to establish standard diagnostic criteria for all patients with HELLP syndrome, necessitating studies consistent with significant population numbers to establish the main signs and symptoms and try to reach consensus on the best markers for the diagnosis and its proper indexes cutting.

PP176. SFLT-1: A possibility of precocious diagnosis of preeclampsia

INTRODUCTION

Preeclampsia (PE) affects 5-8% of all pregnant women and can trigger a severe gestational hypertension framework and eventually develop into eclampsia and HELLP syndrome. Anticipating the damage would be important in order to establish procedures that can reduce adverse outcomes. For this reason, many researches are undertaken to identify ways to make a diagnosis of preeclampsia as early as possible. It has been highlighted in literature the study: the sFlt1 (soluble fms-like tyrosine kinase-1) has been implicated in the precocious diagnosis of pre eclampsia. The sFlt1 is an anti-angiogenic factor produced in response to oxidative stress derived from the deleterious effects of pre-eclampsia.

OBJECTIVES

The objective of the study was to evaluate the role of Soluble fms-like tyrosine kinase-1 in the diagnosis of preeclampsia.

METHODS

This is a review conducted in the database PubMed and Lilacs. For this purpose, we used the following MeSH, "Vascular Endothelial Growth Factor Receptor-1" OR "FLT1 protein, human" AND "Pre-Eclampsia/diagnosis" in PubMed and "Pre-eclampsia" AND "SFLT1A" in Lilacs, resulting in 84 papers. After reading the abstracts of these studies, we selected the articles analyzed taking into consideration the criteria for inclusion and exclusion. We excluded publications that were not in the period under study (2008 to July 2011) and by study design. Including only case-control, cohort and prospective observational. For a critical analysis of the material, we used the following indicators: researcher, years, central theme, participants, study design and primary outcome.

RESULTS

The final results of this study were composed of seven articles and are shown for each target outcome. These vary according to gestational age at which PE is installed and the marker studied (sFlt1 alone or its relation to PlGF - sFlt1/PIGF). Six studies showed greater levels of sFlt1 for the preeclampsia groups when compared to the control group. Significantly differences in antiangiogenic factors seric levels were not found among preeclamptic and eclamptic patients. When associated with another factor, like PIGF, a greater efficacy in the diagnosis of early preeclampsia is shown. Of the studies analyzed, only one (Lynch et al) showed no significant difference between the values of sFlt-1 in groups of early PE, late PE and control for gestational ages between 10 and 15 weeks. As for the relation sFlt-1/PIGF, five studies have considered it even better for PE diagnosis when compared to sFlt-1 isolated.

CONCLUSION

The dosage of sFlt1 may be a relevant resource for the early diagnosis of preeclampsia before the installation of target organ damage, especially if measured in the period between 12 and 28 weeks of gestational age. Whereas sFlt-1 manifests itself before the 20th week, that may be interesting clinical point of view since it is this phase that settles the most severe cases, when the adoption of care could prevent further risks. The relationship sFlt1/PIGF, was more appropriate than the measurement of sFlt1 alone. Additional studies are needed to: amplification of the number of women evaluated, establishing gestational age appropriate for study, serum standard and need to consider the relationship between sFlt1 and other factors pro and/or anti-angiogenic.

Factor analysis, a more accurate method to be used in epidemiological studies of blood pressure in children

The aim of our study is to evaluate whether factor analysis is better able to explain the variability of systolic blood pressure (SBP) and diastolic blood pressure (DBP) when compared with regression analysis, which is the usual tool to study a set of variables related to blood pressure (BP). SBP, DBP, weight, height, BMI, triceps skin-fold, sexual maturation and rurality were studied in 889 children aged 5-18 years (389 boys and 500 girls). The proposed method transforms any set of variables into a set of new variables (factors) which are uncorrelated with each other. One of the factors obtained clearly explains the BP variance of the. With this method, the algorithm accepts all meaningful variables, while regressions reject most of them. This method also explains a larger amount of BP variability, losing as little information as possible. In our sample the percentage of the total variance (communality) explained by the three factors was 80.3% for SBP, 88.1% for DBP in males, 79.3% for SBP and 90.7% for DBP in females. For the same sample, regressions only explained 41.2% in males and 41.9% in females for SBP, 40.9% in males and 47.2% in females for DBP. In conclusion, this method is more accurate for epidemiological studies producing a better overall score than regression analysis, losing almost no information from the sample. Two important strengths of the proposed methodology are as follows. First, it yields a unique, easy to calculate and flexible cardiovascular index for children, thus circumventing the problem of making decisions based on two variables (SBP and DBP). Second, such an index is the result of a methodology where specific BP variability is isolated rather than explained.

Effects of phenethyl alcohol on Bacillus and Streptococcus

The activity of phenethyl alcohol (PEA) on Bacillus cereus, B. megaterium, and Streptococcus faecalis was studied by electron microscopy of thin sections and by the assay of intracellular K+ leakage. S. faecalis was unaffected by PEA at concentrations up to 0.5%, B. cereus was severely damaged by 0.5% PEA, and B. megaterium behaved intermediately. Important membrane ultrastructural alterations were observed in B. cereus cells treated with 0.5% PEA, namely the change in the geometry of the membrane profile from asymmetric to symmetric, the occurrence of prominent, complex mesosome-like structures, and membrane fracturing and solubilization. Protoplasts from B. megaterium were found to be quickly lysed by 0.5% PEA due to the disruption of the cytoplasmic membrane. The electron microscopic observations, together with the results of the study of the K+ efflux from B. cereus and B. megaterium, indicate that PEA primarily and directly damages the cytoplasmic membrane of sensitive bacteria. The breakdown of the permeability barrier probably is responsible for the observed bactericidal action of 0.5% PEA on B. cereus.

Bacterial mesosomes. Real structures or artifacts?

The ultrastructural study of membrane organization in gram-positive bacteria related to the OSO4 fixation conditions revealed that large, complex mesosomes are observed only when the bacteria are subjected to an initial fixation with 0.1%OSO4 in the culture broth, as in the prefixation step of the Ryter-Kellenberger procedure. Evidence was obtained suggesting that the large mesosomes are produced by this prefization. The kinetic study of the membrane morphological alterations occurring during the prefixation of Bacillus cereus with 0.1%OSO4 in the culture broth showed that the amount of mesosome material increases linearly from zero to a maximum observed at 1.7 min of prefixation and that at about this time a maximum is reached for the number of mesosomes per unity of cell area and for the average individual mesosome area. The large mesosomes observed in gram-positives fixed by the complete Ryter-Kellenberger procedure would be the result of the membrane-damaging action of 0.1%OSO4. Such damaging action was deduced from the observation thay 0.1%OSO4 quickly lyses protoplasts and induces a quick and extensive leakage of intracellular K+ from B. cereus and Streptococcus faecalis. In support of that interpretation is the observation that in bacteria subjected to several membrane-damaging treatments, mesosome-like structures are seen after three different fixation procedures. In bacteria initially fixed with 1% OSO4, 4% OSO4 or 2.5% glutaraldehyde, no large complex mesosomes are observed, small and simple invaginations of the cytoplasmic membrane being present. The size of these minute mesosomes is inversely proportional that causes of fixation. Uranyl acetate was found among the studied fixatives the one to the rate the least damage to bacterial membranes. This fixative satisfactorily preserves protoplasts. In bacteria initially fixed with uranyl acetate no mesosomes were found. The results of the present work throw serious doubts on the existence of mesosomes, both large and small, as real structures of bacterial cells. It is proposed that a continuous cytoplasmic membrane without infoldings (mesosomes) would be the real pattern of membrane organization in gram-positives.