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71.
72.
The aim of this study was to establish the relationship between the stiffness of scantlings, approaching structural size materials, and small specimens of 6-year-old Eucalyptus urophylla?×?grandis wood using a resonance technique. The correlation between the elastic modulus (E) of the scantlings in longitudinal vibration and small specimens in flexural vibration was r?=?75 when comparing the scantling values with the averaged values of the specimens per scantling. However, when the E of each single specimen was compared with its respective scantling, the coefficient of correlation decreased to r?=?0.64 in the longitudinal tests and r?=?0.61 in the flexural tests. A roughly linear correlation (r?=?0.59) between specific modulus and loss tangent was obtained for the small specimens of Eucalyptus. In short, the resonance technique rapidly provided a large, accurate data set of mechanical wood properties as required for high-throughput phenotyping in recent genetic studies.  相似文献   
73.
Subolesin/akirin is a well characterized protective antigen highly conserved across vector species and thus potentially useful for the development of a broad-spectrum vaccine for the control of arthropod infestations including hard ticks, mosquitoes, sand flies and the poultry red mite Dermanyssus gallinae. Soft ticks could be also targeted by this vaccine if proved that the soft tick subolesin orthologs are conserved and induce protective immune responses too. However, to date no soft tick subolesin orthologs have been fully characterized nor tested as recombinant antigens in vaccination trials. The objectives of the present work were to clone and characterize the subolesin orthologs from two important vector species of soft ticks as Ornithodoros erraticus and O. moubata, to evaluate the effect of subolesin gene silencing by RNAi, and to test the protective value of the recombinant antigens in vaccination trials. The obtained results demonstrate that both soft tick subolesins are highly conserved showing more than 69% and 74% identity with those of hard ticks in their nucleotide and amino acid sequences, respectively. Additionally, we demonstrate that both soft ticks possess fully operative RNAi machinery, and that subolesin gene silencing by dsRNA injection inhibits oviposition indicating the involvement of subolesin in tick reproduction. Finally, vaccination with the recombinant soft tick subolesins induced a partial protective effect resulting in the reduction of the oviposition rate. These preliminary results encourage further studies on the use of recombinant subolesins as vaccines for the control of soft tick infestations, either alone or in combination with other specific molecules.  相似文献   
74.
The Cavalier King Charles Spaniel (CKCS) is prone to severe early onset mitral valve disease. In this study, 36 purebred CKCS dogs were evaluated for mitral valve murmur and divided into early and late onset groups. A genome-wide genetic approach was used to assess whether the condition is determined by a small number of genetic factors. There were no regions of highly discrepant homo/heterozygosity in the two groups. Similarly, there was no evidence for loci associated with mitral valve murmur in a genome-wide association study. This analysis suggests that familial occurrence of mitral valve murmur in the CKCS breed is not due to a single major gene effect, indicating that breeding strategies to eliminate the disease cannot be based on genotype information at this time.  相似文献   
75.
NetB toxin from Clostridium perfringens is a major virulence factor in necrotic enteritis in poultry. In this study the efficacy of NetB as a vaccine antigen to protect chickens from necrotic enteritis was examined. Broiler chickens were immunized subcutaneously with purified recombinant NetB (rNetB), formalin treated bacterin and cell free toxoid with or without rNetB supplementation. Intestinal lesion scores and NetB antibody levels were measured to determine protection after mild oral gavage, moderate in-feed and heavy in-feed challenges with virulent C. perfringens isolates. Birds immunized with rNetB were significantly protected against necrotic enteritis when challenged with a mild oral dose of virulent bacteria, but were not protected when a more robust challenge was used. Bacterin and cell free toxoid without rNetB supplementation did not protect birds from moderate and severe in-feed challenge. Only birds immunized with bacterin and cell free toxoid supplemented with rNetB showed significant protection against moderate and severe in-feed challenge, with the later giving the greatest protection. Higher NetB antibody titres were observed in birds immunized with rNetB compared to those vaccinated with bacterin or toxoid, suggesting that the in vitro levels of NetB produced by virulent C. perfringens isolates are too low to induce the development of a strong immune response. These results suggest that vaccination with NetB alone may not be sufficient to protect birds from necrotic enteritis in the field, but that in combination with other cellular or cell-free antigens it can significantly protect chickens from disease.  相似文献   
76.
Avian necrotic enteritis is a major economic and welfare issue throughout the global poultry industry and is caused by isolates of Clostridium perfringens that produce NetB toxin. Previously we have shown that birds directly vaccinated with inactivated C. perfringens type A culture supernatant (toxoid) combined with recombinant NetB (rNetB) protein were significantly protected from homologous and heterologous challenge. In the present study the protective effect of maternal immunization was examined. Broiler breeder hens were injected subcutaneously with genetically toxoided rNetB(S254L) alone, C. perfringens type A toxoid and toxoid combined with rNetB(S254L). Vaccination resulted in a strong serum immunoglobulin Y response to NetB in hens immunized with rNetB(S254L) formulations. Anti-NetB antibodies were transferred to the eggs and on into the hatched progeny. Subclinical necrotic enteritis was induced experimentally in the progeny and the occurrence of specific necrotic enteritis lesions evaluated. Birds derived from hens immunized with rNetB(S254L) combined with toxoid and challenged with a homologous strain (EHE-NE18) at either 14 or 21 days post-hatch had significantly lower levels of disease compared to birds from adjuvant only vaccinated hens. In addition, birds from hens immunized with rNetB(S254L) alone were significantly protected when challenged at 14 days post-hatch. These results demonstrate that maternal immunization with a NetB-enhanced toxoid vaccine is a promising method for the control of necrotic enteritis in young broiler chickens.  相似文献   
77.
78.

Tree growth and wood density are influenced by forest management. Nevertheless, few studies have evaluated their variability responses to fertilizer treatments at inter-annual, inter-tree and stand-production levels. Therefore, the annual ring width (RW) and density (RD) of sixty 17-year-old-Pinus taeda trees fertilized with six doses of composted pulp-mill sludge (CPMS) were analyzed. Ten trees for each treatment were felled and from which wood discs were taken at different trunk heights. The annual RW and RD were provided by X-ray microdensitometry, synchronized and the trunk basic specific gravity (SGB) and biomass calculated. The effects of CPMS treatments were explored using interaction of variables RW and RD with cambial age, diameter, trunk SGB and biomass production. Trees treated with CPMS grow faster, increasing their biomass (up to 108%), presenting lower wood density values (significant up to the 6th year) and reaching the mature wood later than untreated trees. Furthermore, the potential use of RW and RD in allometric equations showed good accuracy to predict trunk SGB and biomass. Altogether, our results indicated that ring width and density revealed the impacts of fertilization treatment on wood quality and production. Our study also provides useful information for forest managers on the fertilization monitoring process.

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79.
80.
The maize of Latin America, with its enormous diversity, has played an important role in the development of modern maize cultivars of the American continent. Peruvian highland maize shows a high degree of variation stemming from its history of cultivation by Andean farmers. Multivariate statistical methods for classifying accessions have become powerful tools for classifying genetic resources conservation and the formation of core subsets. This study has two objectives: (1) to use a numerical classification strategy for classifying eight Peruvian highland races of maize based on six vegetative traits evaluated in two years and (2) to compare this classification with the existing racial classification. The numerical classification maintained the main structure of the eight races, but reclassified parts of the races into new groups (Gi). The new groups are more separated and well defined with a decreasing accession within group × environment interaction. Most of the accessions from G1 are from Cusco Gigante, all of the accessions from G3 (except one) are from Confite Morocho, and all of the accessions from G7 are from Chullpi. Group G2 has four accessions from Huayleño and four accessions from Paro, whereas G4 has four accessions from Huayleño and five accessions from San Geronimo. Group G5 has accessions from four races, and G6 and G8 formed small groups with two and one accession each, respectively. These groups can be used for forming core subsets for the purpose of germplasm enhancement and assembling gene pools for further breeding.  相似文献   
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