Rubber tree early selection for yield stability in time and among locations

Rubber production in the rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. Arg.] can be expressed differently in different environments. Thus the objective of the present study was to select productive progenies, stable and responsive in time and among locations. Thirty progenies were assessed by early yield tests at three ages and in three locations. A randomized block design was used with three replications and ten plants per plot, in 3 × 3 m spacing. The procedure of the mixed linear Reml/Blup model—restricted maximum likelihood/best non-biased linear prediction was used in the genetic statistical analyses. In all the individual analyses, the values observed for the progeny average heritability ( $ \hat{h}_{pa}^{2} $ ) were greater than those of the additive effect based on single individuals ( $ \hat{h}_{a}^{2} $ ) and within plot additive ( $ \hat{h}_{ad}^{2} $ ). In the joint analyses in time, there was genotype × test interaction in the three locations. When 20 % of the best progenies were selected the predicted genetic gains were: Colina G_G = 24.63 %, Selvíria G_G = 13.63 %, and Votuporanga G_G = 25.39 %. Two progenies were among the best in the analyses in the time and between locations. In the joint analysis among locations there was only genotype × location interaction in the first early test. In this test, selecting 20 %, the general predicted genetic gain was G_G = 25.10 %. Identifying progenies with high and stable yield over time and among locations contributes to the efficiency of the genetic breeding program. The relative performance of the progenies varies depending of the age of early selection test.     

Biosorption of macronutrients by Brazilian tropical peats

The objective of this work was to evaluate the adsorption of macronutrients calcium, potassium, magnesium, nitrogen, and phosphorus in two Brazilian tropical peat samples, investigating the effect of pH and determining the kinetics of the adsorption process. Two different Brazilian tropical peat samples were characterized using FTIR, TG, and SEM techniques. Different pH conditions were tested, as well as different mass concentrations of the peats. Differences in the chemical structures of the peat samples directly influenced the adsorptive capacities for the macronutrients. The adsorptive capacity for nitrogen was highest at pH 3, while the best adsorption of calcium and potassium was obtained at pH 6. The best fit to the data was provided by the pseudo-second-order model, which confirmed the rapid adsorption of calcium by both peats.     

Weak effect of edges on avian nesting success in fragmented and forested landscapes in Ontario,Canada

We studied the effects of anthropogenic edges on predation and parasitism of forest bird nests in an agriculturally fragmented landscape and a continuously forested landscape in Ontario, Canada. Nesting data were collected at 1937 nests across 10 species in the fragmented landscape from 2002–2008, and 464 nests across 4 species in the continuously forested landscape from 2006–2008. Brood parasitism only occurred in the fragmented landscape, and was positively related to the proportion of rural grassland and row crop habitats within 500-m of nests. Daily nest survival was negatively related to the density of roads within 500-m of nests in the fragmented landscape, but was not influenced by distance to anthropogenic edge in either landscape. Predation rates were higher in the fragmented landscape for Ovenbird and Rose-breasted Grosbeak nests, but did not differ between landscapes for Veery and American Redstart nests. Uniformly high predation in the fragmented landscape may be a result of (1) matrix predators that penetrate deep (>300 m) into the forest interior, or (2) the additive effect of forest-dependent and matrix-associated predators that results in high predation pressure in both edge and interior habitats. Further research focused on the identification of nest predators, their population dynamics, and habitat use is required to understand the underlying mechanisms leading to uniformly high nest predation in fragmented landscapes.     

Acaricidal activity of Calea serrata (Asteraceae) on Boophilus microplus and Rhipicephalus sanguineus

Calea serrata (Asteraceae) is an endemic Southern Brazilian plant species used for religious and medicinal purposes. Previous study revealed the presence of chromenes, a class of natural compounds that possess insecticidal properties. This study reports the effect of the hexane extract from the aerial parts of this plant on egg hatchability, egg production and mortality rates of newly hatched larvae of the cattle tick Boophilus microplus. Larvae of Rhipicephalus sanguineus, the brown dog tick, received the same treatment. The extract was toxic to the eggs of B. microplus and to the larvae of both B. microplus and R. sanguineus.     

Characterization and growth conditions of Vibrio parahaemolyticus strains with different virulence degrees that cause acute hepatopancreatic necrosis disease in Litopenaeus vannamei

The phenotypic characteristics and growth kinetics at several temperatures, salinities, and pH values of three Vibrio parahaemolyticus (Vp) strains with different virulence and one nonpathogenic strain were evaluated. Independent of the virulence of the strain, a high metabolic diversity was found, which yielded different colored phenotypes on the CHROMagar? Vibrio. All strains were resistant to ampicillin and carbenicillin, and Vp AHPND+ organisms were the most sensitive to enrofloxacin. The exponential growth of Vp strains started at 1–2 hr of incubation, although no relationship was observed between the bacterial density and degree of virulence. Moreover, the growth of the most virulent strain was independent of the nutrients in the incubation media during the initial hour postinoculation. No strain grew at 4°C in 0% NaCl and pH 4, but only Vp AHPND+ grew at 44°C. For all strains, the lag phase was proportional to the NaCl concentration, and the growth was better at pH 8–9. However, the Vp AHPND? strain displayed a greater variability, was more sensitive to extreme conditions, and showed a lag phase of 9 hr independent of the pH.     

Clinical outcome following pneumonectomy for management of chronic pyothorax in four cats

Pneumonectomy is the resection of all lung lobes from one side of the thorax. The clinical findings, treatment and outcome of four cases of feline chronic pyothorax managed with exploratory thoracotomy and pneumonectomy are reported. All cases were initially medically managed with thoracic drain placement and antibiosis. However, resolution was not achieved with medical therapy and diagnostic imaging findings consistent with an area of abscessation or marked lung lobe consolidation were identified, supporting a decision for surgical management. Surgical exploration was performed via median sternotomy and, on the basis of gross inspection, non-functional lung was removed. A left-sided pneumonectomy was performed in three cats and a right-sided pneumonectomy in one. All cases survived to discharge and an excellent quality of life was reported on long-term follow-up. Pneumonectomy appears to be well tolerated in the cat.     

Development of piscirickettsiosis in Atlantic salmon (Salmo salar L.) smolts after intraperitoneal and cohabitant challenge using an EM90‐like isolate: A comparative study

Piscirickettsiosis, caused by the intracellular Gram‐negative bacteria Piscirickettsia salmonis, is at present the most devastating disease in the Chilean salmon industry. The aim of this study was to analyse disease development after challenge with a P. salmonis strain (EM90‐like) under a controlled environment by comparing intraperitoneal challenge with cohabitation challenge. The P. salmonis EM90‐like isolate was cultured in a liquid medium for the challenge of 400 Atlantic salmon (Salmo salar) smolts. Cumulative mortality was registered, necropsy was performed, and bacterial distribution in the tissues and histopathological changes were analysed. The results revealed a similar progression of the disease for the two different challenge models. Pathological and histopathological changes became more visible during the development of the clinical phase of the disease. Bacterial DNA was identified in all the analysed tissues indicating a systemic infection. Bacterial tropism to visceral organs was demonstrated by real‐time quantitative PCR and immunohistochemistry. Better knowledge of disease development during P. salmonis infection may contribute to further development of challenge models that mimic the field situation during piscirickettsiosis outbreaks. The models can be used to develop and test future preventive measures against the disease.     

Visualization and functional analysis of RNA-dependent RNA polymerase lattices

Positive-strand RNA viruses such as poliovirus replicate their genomes on intracellular membranes of their eukaryotic hosts. Electron microscopy has revealed that purified poliovirus RNA-dependent RNA polymerase forms planar and tubular oligomeric arrays. The structural integrity of these arrays correlates with cooperative RNA binding and RNA elongation and is sensitive to mutations that disrupt intermolecular contacts predicted by the polymerase structure. Membranous vesicles isolated from poliovirus-infected cells contain structures consistent with the presence of two-dimensional polymerase arrays on their surfaces during infection. Therefore, host cytoplasmic membranes may function as physical foundations for two-dimensional polymerase arrays, conferring the advantages of surface catalysis to viral RNA replication.