Isolation and characterisation of equine influenza viruses (H3N8) from Europe and North America from 2008 to 2009

Like other influenza A viruses, equine influenza virus undergoes antigenic drift. It is therefore essential that surveillance is carried out to ensure that recommended strains for inclusion in vaccines are kept up to date. Here we report antigenic and genetic characterisation carried out on equine influenza virus strains isolated in North America and Europe over a 2-year period from 2008 to 2009. Nasopharyngeal swabs were taken from equines showing acute clinical signs and submitted to diagnostic laboratories for testing and virus isolation in eggs. The sequence of the HA1 portion of the viral haemagglutinin was determined for each strain. Where possible, sequence was determined directly from swab material as well as from virus isolated in eggs. In Europe, 20 viruses were isolated from 15 sporadic outbreaks and 5 viruses were isolated from North America. All of the European and North American viruses were characterised as members of the Florida sublineage, with similarity to A/eq/Lincolnshire/1/07 (clade 1) or A/eq/Richmond/1/07 (clade 2). Antigenic characterisation by haemagglutination inhibition assay indicated that the two clades could be readily distinguished and there were also at least seven amino acid differences between them. The selection of vaccine strains for 2010 by the expert surveillance panel have taken these differences into account and it is now recommended that representatives of both Florida clade 1 and clade 2 are included in vaccines.     

Mapping genomic regions for reproductive traits in beef cattle: Inclusion of the X chromosome

Although the second largest chromosome of the genome, the X chromosome is usually excluded from genome-wide association studies (GWAS). Considering the presence and importance of genes on this chromosome that are involved in reproduction, the aim of this study was to evaluate the effect of its inclusion in GWAS on reproductive traits (scrotal circumference [SC], early pregnancy [P16] and age at first calving [AFC]) in a Nelore herd. Genotype data from 3,263 animals with the above-mentioned phenotypes were used. The results showed an increase in the variances explained by the autosomal markers for all traits when the X chromosome was not included. For SC, there was an increase of more than 10% for the windows on chromosomes 2 and 6. For P16, the effect was increased by almost 20% for windows on chromosome 5. The same pattern was found for AFC, with an increase of more than 10% for the most important windows. The results indicate that the noninclusion of the X chromosome can overestimate the effects of autosomes on SC, P16 and AFC not only because of the additive effect of the X chromosome itself but also because of its epistatic effect on autosomal genes.     

Ruminal and histological characteristics and nitrogen balance in lamb fed diets containing cactus as the only roughage

Tropical Animal Health and Production - This study examined rumen fermentation, histological, blood, and urinary characteristics as well as ammoniacal nitrogen concentration, pH, nitrogen balance,...     

Effect of root temperature on carob growth: Nitrate versus ammonium nutrition

The response of carob (Ceratonia siliqua L.) seedlings grown at different root zone temperatures affected by nitrate and ammonium nutrition was studied. When root temperatures ranged from 10 to 35°C, ammonium‐fed plants were significantly larger than nitrate‐fed plants. Ammonium‐fed plants displayed toxicity symptoms and were much smaller at 40°C root temperature in comparison with the nitrate‐fed plants grown at the same root temperature. Root/shoot ratio slightly increase with root temperature in ammonium‐ and nitrate‐fed plants in a similar way, and shoot demand per root unit decreased with root temperature between 15 and 25°C. There was a general increase in net photosynthesis with root temperature, though nitrate‐fed plants were more sensitive to low and ammonium‐fed plants to high temperatures. Increasing the root temperature of ammonium fed plants from 10 to 40°C leads to a 30% increase in the amount of photosynthates sent to the roots. The presence of ammonium resulted in the distribution of newly fixed carbon away from carbohydrates and into nitrogen compounds. Potassium, calcium, and nitrogen content of the plants also increased with increasing root temperature.     

Effects of reducing leaf area and tuber number on the growth rates of tubers on individual potato plants

Summary Potato plants (Solanum tuberosum L. cv. Ostara) were grown in nutrient solution culture in a controlled environment. Growth rates of individual tubers were determined daily by measuring the increase in their volume. Decreasing the source:sink ratio of individual plants by removing half of the leaf area, decreased tuber growth rate per plant by 50%. Increasing the source: sink ratio of individual plants by cooling to 8°C, or by removing individual tubers of known growth rate, increased the growth rate of non-cooled, remaining tubers within 2–4 days. The potential of the tubers to increase their growth rates was not related to the date of tuber removal after tuber initiation. It is concluded that during the phase of linear tuber bulking, tuber growth is neither limited by pathway nor sink, but by the source capacity of the plant.

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Zusammenfassung Kartoffelpflanzen (Solanum tuberosum L. cv. Ostara) wuchsen in N?hrl?sung unter kontrollierten Umweltbedingungen (14 h Tagesl?nge, 22°C/18°C Tag/Nachttemperatur, 60–80% relative Luftfeuchtigkeit, Licht-intensit?t in Pflanzenh?he ≈380 μE m⁻² s⁻¹). Die Wachstumsraten der einzelnen Knollen wurden t?glich aus ihrer Volumenzunahme bestimmt. Die Auswirkungen von Source- und Sink-Manipulationen auf die Wachstumsraten der Knollen wurden w?hrend der Phase linearen Knollenwachstums untersucht. Eine Reduzierung der Source-St?rke einzelner Pflanzen durch Entfernen jedes 2. Fiederblattes oder eines von 2 gleichwertigen hauptstengeln pro Pflanze bewirkte eine sofortige Abnahme des Knollenwachstums pro Pflanze um 50% (Abb. 4). In den meisten F?llen nahm auch die Wachtstumsrate der einzelnen Knollen an den Pflanzen um etwa 50% ab (Abb. 5). Durch Kühlung einzelner Knollen auf +8°C wurden deren Wachstumsraten im Durchschnitt von 4,5 auf 1,6 cm³ d⁻¹ gesenkt, w?hrend gleichzeitig die Wachstumsraten der ungekühlten Knollen von 2,8 auf 5,2 cm³ d⁻¹ anstiegen (Tab. 1). Das Entfernen einzelner Knollen, die bis dahin durch-schnittlich zu 60% am Gesamtknollenwachstum pro Pflanze beteiligt waren, führte innerhalb von 2–4 Tagen zu einem mehr als doppelt so schnellen Wachstum der an den Pflanzen verbliebenen Knollen, so dass das Gesamtknollenwachstum pro Pflanze nicht signifikant ver?ndert wurde (Abb. 1). Hierbei wurden die Wachstumsraten aller an der Pflanze verbliebenen Knollen erh?ht, wobei Wachstumsraten von mehr als 8 cm³ pro Einzelknolle und Tag erreicht wurden (Abb. 3). Die F?higkeit der Knollen, ihre Wachstumsrate dem jeweiligen Assimilatangebot anzupassen, war nicht davon abh?ngig, zu welchem Zeitpunkt nach der Knolleninduktion (10–30 d) einzelne Knollen entfernt wurden (Abb. 2). Aus den Untersuchungen wird gefolgert, dass in der phase des linearen Knollenwachstums eine Limitierung des Knollenwachstums weder durch den transportweg noch durch die Speicherf?higkeit der Knollen bewirkt wird, sondern durch die F?higkeit des oberirdischen Sprosses, Assimilate zur Verfügung zu stellen.

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Résumé Des plantes de pommes de terre (Solanum tuberosum L. cv. Ostara) sont cultivées dans une solution nutritive sous atmosphère contr?lée (longueur de jours 14 h; températures jour/nuit 22°C/18°C; humidité relative de l'air 60 à 80%; intensité du rayonnement photosynthétique à hauteur de la plante ≃380 μF m⁻² s⁻¹). Le grossissement des tubercules est déterminé chaque jour en mesurant l'augmentation de leur volume. Les effets de la source d'assimilation et du puits d'absorption sont analysés pendant la phase linéaire de grossissement des tubercules. Une diminution du rapport source: puits d'absorption est obtenue en supprimant la moitié de la surface foliaire de chaque plante. Le grossissement des tubercules diminue en conséquence de 50% (figure 4). Mis à part quelques exceptions, les taux de croissance des tubercules individuels baissent également de 50% (figure 5). Le refroidissement de certains tubercules d'une même plante à 8°C entra?ne une diminution moyenne de leur grossissement de 4,5 à 1,6 cm³/jour. Dans le même temps, les autres tubercules voient leur croissance augmenter de 2,8 à 5,2 cm³/jour (tableau 1). La suppression de certains tubercules qui avaient contribué pour 60% au grossissement total obtenu par plante, entr?ne une augmentation de croissance de plus de 100% des tubercules restants, ceci en moins de 2 à 4 jours. De ce fait, la croissance totale, par plante n'est pas significativement inférieure (figure 1). Après suppression de certains tubercules, on constate que pour tous les tubercules restants leur grossissement augmente et le taux maximum de croissance atteint 8 cm³/jour (figure 3). Les tubercules ajustent leur grossissement en fonction de l'apport effectif de photosynthèse sans liaison avec la date de suppression de certains tubercules après leur initiation (figure 2). En conclusion, pendant la phase linéaire de grossisement, la croissance des tubercules n'est pas limitée par le puits d'absorption, mais par la capacité de la source d'assimilation de la plante.

     

Bacterial community associated with the ambrosia beetle Platypus cylindrus on declining Quercus suber trees in the Alentejo region of Portugal

In Portugal, the oak pinhole borer Platypus cylindrus and its mycobiota have been associated with cork oak (Quercus suber) death, but no knowledge exists regarding the associated bacterial community. However, it is known that some bacteria are important for ambrosia beetle symbiosis and play a role in oak tree health. To explore the bacteria associated with this beetle and its host, with the ultimate goal of highlighting potential roles in oak decline, this study used a culture-dependent approach for strain isolation and phylogenetic identification using 16S rRNA gene sequencing and multilocus sequence analysis (MLSA). The bored galleries of different cork oak trees from a cork stand in Alentejo, together with the body and mycangia of adult beetles, were investigated. The samples revealed a diverse community comprising 500 isolates with 64 distinct types of bacterial colonies. Sixty-eight strains were selected for sequencing and used for phylogenetic analysis, 40 from wood galleries and 28 from beetles. Thirty-two genera of bacteria were identified, 18 of which were described for the first time within oak–beetle interactions. Major taxonomic groups were Actinobacteria in beetles and Enterobacterales in wood galleries. Although specific oak bacterial pathogens were not detected, a group of distinct strains detected in wood galleries, potentially belonging to a new Pectobacteriaceae species, were able to produce mild symptoms on cork oak plantlets. This study reports for the first time the biodiversity of culturable bacteria associated with the Q. suber–P. cylindrus interaction, their relevance to both organisms and the possible contribution to oak decline.     

Introgression of Xa4, Xa7 and Xa21 for resistance to bacterial blight in thermosensitive genetic male sterile rice (Oryza sativa L.) for the development of two-line hybrids

Bacterial blight (BB) of rice caused by X. oryzae pv. oryzae is a major production constraint in commercial hybrid rice production in the Philippines because most of the parental lines used in hybrid production do not carry resistance genes against the pathogen. In this study, three bacterial blight resistance genes, Xa4, Xa7 and Xa21, were introgressed to a temperature-sensitive genetic male sterile (TGMS1) line. A three-way cross of AR32-19-3-3/TGMS1//IRBB4/7 (PR36944) was made to produce 1,364 F₂ plants carrying various combinations of Xa4, Xa7 and Xa21. Individual plants were characterized for reaction to bacterial blight PXO61 (race 1), PXO86 (race 2), PXO99 (race 6) and pollen sterility. Of 144 F₂ plants demonstrating resistance against PXO61, PXO86 and PXO99, 22 exhibited highly resistant phenotypes with mean lesion lengths ranging from 0.37–2.97 cm. Analysis of disease reaction identified 20 potential TGMS F₂ plants containing Xa4, Xa7 and Xa21 while 78 plants with Xa4 + Xa7. Phenotypic and polymerase chain reaction (PCR) analyses confirmed PR36944-450, PR36944-473 and PR36944-700 as homozygous for Xa7 and Xa21 and highly resistant to all three Xoo races. Fertility of PR36944-450 and PR36944-700 was restored at permissive temperature in a growth chamber. BB-resistant TGMS lines should facilitate breeding two-line hybrids in the tropics.     

Response to two cycles of divergent selection for grain yield under drought stress in four rice breeding populations

Drought is a major production constraint in rainfed rice (Oryza sativa L.). Lack of effective selection criteria is a major limitation hampering progress in breeding for drought tolerance. In an earlier report, we showed in two populations that one cycle of direct selection was effective in increasing grain yield under stress. In the present study, we retested the efficiency of direct selection for grain yield under drought stress in rice using four populations derived from crossing upland-adapted, drought-tolerant varieties (Apo, Vandana) to high-yielding, lowland-adapted, drought-susceptible varieties (IR64, IR72). Each population was subjected to two cycles of divergent selection either under drought stress in upland or under nonstress conditions in lowland conditions. Following selection, approximately 40 high-yielding lines selected under each protocol from each population, along with a set of unselected lines, were evaluated in a series of selection response trials over a range of moisture levels. Significant response to direct selection under stress was realized in 9 out of 15 combinations of populations and stress environments, and in 6 of the 7 severe stress trials. Averaging over all the populations and stress environments, the stress-selected lines had a yield advantage of 25 and 37% over nonstress-selected and random lines, respectively. In contrast to this, under nonstress, the nonstress-selected lines had an average yield advantage of only 7 and 13% over stress-selected and random lines, respectively. Direct selection in managed stress trials during dry seasons gave significant response (25% on average relative to indirect selection in nonstress conditions) under naturally occurring wet season stress. In addition, direct selection under stress in upland gave an average gain of 16 and 45% over nonstress-selected and random lines, respectively, under stress in lowland. The yield advantage of the stress-selected lines appears to result mainly from maintenance of higher harvest index. These results show that direct selection for grain yield under stress is effective and does not reduce yield potential. Overall, this is the first report in rice demonstrating that (a) selection under managed drought stress in the dry season can result in yield gains under natural stress in the wet season, and (b) that selection under upland drought stress can, at least under the conditions of the present study, result in gains under lowland drought conditions.     

Prevalence and inheritance of canine elbow dysplasia in German Rottweiler

A total of 2114 scores of elbow arthrosis from the official screening programme of the German Rottweiler Breeding Association (ADRK) were analysed in respect of prevalence and genetic disposition. 45.8% showed no signs of arthritis, 40.6% were scored in Grade 1 with minor osteophytes and 13.6% were affected by arthritis of clinical relevance (Grade 2 and 3). REML estimates showed a heritability of 28% and a litter variance of 6.4%. The only significant environmental fixed effect was gender. 39.1% of the male and 51.5% of the female were free from ED which corresponds with 19.2% of the male and only 8.8% of the female in the critical ED classes of Grade 2 and 3. Differences between the years of examination could be explained by genetic gain. Month of birth as well as age at examination, in the range covered by this study, was not significant. It was stated that the effect of bodyweight should be tested before starting a breeding programme.