Tangential Chains of Neuroblasts in the Subpial Layer of the Adult Rabbit Cerebellum

Veterinary Research Communications -     

QTL mapping and analysis of epistatic interactions for grain yield and yield-related traits in <Emphasis Type="Italic">Triticum turgidum</Emphasis> L. var. <Emphasis Type="Italic">durum</Emphasis>

A quantitative trait loci (QTL) analysis of grain yield and yield-related traits was performed on 93 durum wheat recombinant inbred lines derived from the cross UC1113 × Kofa. The mapping population and parental lines were analyzed considering 19 traits assessed in different Argentine environments, namely grain yield, heading date, flowering time, plant height, biomass per plant, and spikelet number per ear, among others. A total of 224 QTL with logarithm of odds ratio (LOD) ≥ 3 and 47 additional QTL with LOD > 2.0 were detected. These QTL were clustered in 35 regions with overlapping QTL, and 12 genomic regions were associated with only one phenotypic trait. The regions with the highest number of multi-trait and stable QTL were 3BS.1, 3BS.2, 2BS.1, 1BL.1, 3AL.1, 1AS, and 4AL.3. The effects of epistatic QTL and QTL × environment interactions were also analyzed. QTL putatively located at major gene loci (Rht, Vrn, Eps, and Ppd) as well as additional major/minor QTL involved in the complex genetic basis of yield-related traits expressed in Argentine environments were identified. Interestingly, the 3AL.1 region was found to increase yield without altering grain quality or crop phenology.     

Spatial patterns of the Citrus leprosis virus and its associated mite vector in systems without intervention

Leprosis is caused by the Citrus leprosis virus cytoplasmic type and is vectored by the mite Brevipalpus yothersi. Miticide applications, which cost $54 million annually, are based on inspection for the presence of mites. The aim of the present study was to characterize the spatial patterns of B. yothersi-infested trees and trees with leprosis symptoms for further improvement in sampling and disease control. The presence of mites and the occurrence of leprosis were assessed over two years in 1160 Valencia trees and 720 Natal trees in a commercial sweet orange grove in Sao Paulo State, Brazil. To assess the natural growth and dispersal of mites and leprosis, mite populations were not controlled during the experimental period. Maps of mite-infested trees and trees with leprosis symptoms were analysed at three different levels of spatial hierarchy using complementary methods, i.e. among adjacent trees within and across rows, within quadrats, and the strength and orientation of aggregation among quadrats. The study showed that the spatial patterns of virus-infected and mite-infested trees were different, with a strong aggregation pattern of trees with leprosis symptoms that increased over time. Conversely, the spatial pattern of B. yothersi showed randomness or weak aggregation at all three spatial hierarchical levels. Disease incidence increased steadily in plots of both cultivars, unlike in mite-infested trees where incidence fluctuated over time. These results have important implications for the development of better management strategies for leprosis. Sampling methods and action thresholds for mite control should consider primary disease inoculum in addition to the incidence of mites.     

Resistance screening of breeding lines and commercial tomato cultivars for <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> and <Emphasis Type="Italic">M. javanica</Emphasis> populations (Nematoda) from Ethiopia

Soil and root samples were collected from major tomato growing areas of Ethiopia during the 2012/2013 growing season to identify root-knot nematode problems. DNA-based and isozyme techniques revealed that Meloidogyne incognita and M. javanica were the predominant Meloidogyne species across the sampled areas. The aggressiveness of different populations of these species was assessed on tomato cultivars Marmande and Moneymaker. The two most aggressive populations of each species were selected and further tested on 33 tomato genotypes. The resistance screening and mechanism of resistance was performed after inoculation with 100 freshly hatched (<24 h) second-stage juveniles (J2). Eight weeks after inoculation the number of egg masses produced on each cultivar was assessed. For the resistance mechanism study, J2 penetration and their subsequent development inside the tomato roots were examined at 1, 2, 4 and 6 weeks after inoculation. On both cultivars Marmande and Moneymaker all M. incognita and M. javanica populations formed a high number of egg masses indicating highly aggressive behaviour. Populations from ‘Jittu’ and ‘Babile’ for M. incognita and ‘Jittu’ and ‘Koka’ for M. javanica were selected as most aggressive. None of the 33 tomato genotypes were immune for these M. incognita and M. javanica populations. However, several tomato genotypes were found to have a significant effect on the number of egg masses produced indicating possible resistance. For M. javanica populations there were more plants from cultivars or breeding lines on which no egg masses were found compared to M. incognita populations. The lowest number of egg masses for both populations of M. incognita was produced on cultivars Bridget40, Galilea, and Irma while for M. javanica it was on Assila, Eden, Galilea, Tisey, CLN-2366A, CLN-2366B and CLN-2366C. Tomato genotypes, time (weeks after inoculation) and their interaction were significant sources of variation for J2 penetration and their subsequent development inside the tomato roots. Differential penetration was found in breeding lines such as CLN-2366A, CLN-2366B and CLN-2366C, but many of the selected tomato genotypes resistance for the tested M. incognita and M. javanica populations were expressed by delayed nematode development. Therefore, developing a simple screening technique to be used by local farmers or extension workers is crucial to facilitate selection of a suitable cultivar.     

Meta-analysis of fungicide efficacy on soybean target spot and cost–benefit assessment

Target spot of soybean has spread in Brazil, the southeastern United States and Argentina in the last decade. A collaborative network of field Uniform Fungicide Trials (UFT) in Brazil was created in 2011 to study the target spot control efficacy of fungicides, including azoxystrobin + benzovindiflupyr (AZ_BF), carbendazim (CZM), fluxapyroxad + pyraclostrobin (FLUX_PYRA), epoxiconazole + FLUX_PYRA (EPO_FLUX_PYRA), mancozeb (MZB) and prothioconazole + trifloxystrobin (PROT_TRIF). Network meta-analysis was used to conduct a quantitative synthesis of UFT data collected from 2012 to 2016 and to evaluate the effects of disease pressure (DP, low ≤ 35% target spot severity in the nontreated control < high) and year of experiment on the overall mean efficacy and yield response to each of the tested fungicides. Based on mean percentage control of target spot severity, the tested fungicides fall into three efficacy groups (EG): high EG, FLUX_PYRA (76.2% control relative to the nontreated control) and EPO_FLUX_PYRA (75.7% control); intermediate EG, PROT_TRIF (66.5% control) and low EG, MZB (49.6% control), AZ_BF (46.7% control) and CZM (32.4% control). DP had a significant effect on yield response. At DP_Low, the highest response was due to PROT_TRIF (+342 kg ha⁻¹, +12.8%) and EPO_FLUX_PYRA (+295.5 kg ha⁻¹, +11.2%), whereas at DP_High, EPO_FLUX_PYRA and FLUX_PYRA outperformed the other treatments, with yield responses of 503 kg ha⁻¹ (+20.2%) and 469 kg ha⁻¹ (+19.1%), respectively. The probability of a positive return on fungicide investment ranged from 0.26 to 0.56 at DP_Low and from 0.34 to 0.66 at DP_High.     

杭椒采收期内辣椒素类物质和维生素C的动态变化

  目的  研究杭椒Capsicum annuum ‘Hangzhou Jizhua’בJilin Zaojiao’果实辣椒素、维生素C等物质在采收期的动态变化，以确定最佳采收期。  方法  选取4个常见杭椒品种，采用高效液相色谱法分别测定开花后14、21、28、35、42、49、56 d采收的果实中辣椒素、二氢辣椒素和维生素C以及干物质质量分数。  结果  采收期内4个杭椒品种果实辣椒素类物质质量分数不同，品种间差异显著(P＜0.05)；维生素C质量分数和干物质相对含量随果实成熟度增加而升高。  结论  花后49 d是杭椒果实最佳采收期，此时果实成熟度好，辣椒素类物质、维生素C质量分数和干物质相对含量均较高。采收期内不同品种辣椒素类物质质量变化差异大，具体采收计划应综合种植品种、市场需求和供求关系等多方面因素考虑。图4表3参27     

Digestive Enzyme Activity during Larval Development of Black Snook,Centropomus nigrescens

Black snook, Centropomus nigrescens, have been identified as a promising candidate for aquaculture although, like many of the Centropomid species, high mortality associated with early larval stages presents a significant bottleneck to their commercialization. The digestive capacity of black snook larvae throughout the first 37 d after hatch (d.a.h.) was evaluated by quantifying digestive enzyme activities using biochemical techniques. Results showed that black snook larvae have alkaline proteases at hatching, which are known to be important during the first days of feeding for digestion. Toward the end of the study, acid proteases concentration increased (37 d.a.h.). Enzymes for lipid digestion, pancreatic lipase and bile salt‐activated lipase, were already present in the larvae before exogenous feeding commenced, and their activity increased with age and growth (length). Intracellular digestion, measured as the activity of leucine‐alanine peptidase, was high early on (5 d.a.h.) and decreased as development progressed (next 32 d). In contrast, alkaline phosphatase activity was lowest at first feeding and subsequently increased with age. Overall patterns in enzyme activity suggest the possibility of live feed weaning before 32 d.a.h. if artificial diets can be properly balanced.