Energy and protein requirements for maintenance and growth of Boer crossbred kids

Meat production by goats has become an important livestock enterprise in several parts of the world. Nonetheless, energy and protein requirements of meat goats have not been defined thoroughly. The objective of this study was to determine the energy and protein requirements for maintenance and growth of 34 (3/4) Boer x (1/4) Saanen crossbred, intact male kids (20.5 +/- 0.24 kg of initial BW). The baseline group was 7 randomly selected kids, averaging 21.2 +/- 0.36 kg of BW. An intermediate group consisted of 6 randomly selected kids, fed for ad libitum intake, that were slaughtered when they reached an average BW of 28.2 +/- 0.39 kg. The remaining kids (n = 21) were allocated randomly on d 0 to 3 levels of DMI (treatments were ad libitum or restricted to 70 or 40% of the ad libitum intake) within 7 slaughter groups. A slaughter group contained 1 kid from each treatment, and kids were slaughtered when the ad libitum treatment kid reached 35 kg of BW. Individual body components (head plus feet, hide, internal organs plus blood, and carcass) were weighed, ground, mixed, and subsampled for chemical analyses. Initial body composition was determined using equations developed from the composition of the baseline kids. The calculated daily maintenance requirement for NE was 77.3 +/- 1.05 kcal/kg(0.75) of empty BW (EBW) or 67.4 +/- 1.04 kcal/kg(0.75) of shrunk BW. The daily ME requirement for maintenance (118.1 kcal/kg(0.75) of EBW or 103.0 kcal/kg(0.75) of shrunk BW) was calculated by iteration, assuming that the heat produced was equal to the ME intake at maintenance. The partial efficiency of use of ME for NE below maintenance was 0.65. A value of 2.44 +/- 0.4 g of net protein/kg(0.75) of EBW for daily maintenance was determined. Net energy requirements for growth ranged from 2.55 to 3.0 Mcal/kg of EBW gain at 20 and 35 kg of BW, and net protein requirements for growth ranged from 178.8 to 185.2 g/kg of EBW gain. These results suggest that NE and net protein requirements for growing meat goats exceed the requirements previously published for dairy goats. Moreover, results from this study suggest that the N requirement for maintenance for growing goats is greater than the established recommendations.     

Expression of Gab2 in human osteosarcoma U2-OS cells

AIM: To investigate the expression of Grb2-associated binding protein 2 (Gab2) in human osteosarcoma cells and its relationship with the invasion and metastases of human osteosarcoma cells. METHODS: The technique of small RNA interference was used to transfect human osteosarcoma U2-OS cell lines. Western blotting and RT-PCR were used to detect the protein and mRNA expression of Gab2 in transfected U2-OS cells. After transfection, through chemotaxis and invasion assays in vitro, the cell migration and invasion abilities were detected. RESULTS: After transfection, the expression of Gab2 at mRNA and protein levels in Gab2 siRNA transfected cells (SiGab2/U2-OS) was lower than that in scrambled siRNA transfected cells (Scr/U2-OS) and U2-OS cells. After stimulation with epidermal growth factor (EGF) at concentration of 10 μg/L, the migration SiGab2/U2-OS cells was significantly less than Scr/U2-OS cells and U2-OS cells (P<0.01). The number of invasion cells of SiGab2/U2-OS group was significantly lower than the other 2 control groups (P<0.01). CONCLUSION: Inhibition of Gab2 expression obviously attenuates the migration and invasion abilities of human osteosarcoma U2-OS cell line.     

A molecular marker linked to the Prv1 gene that confers resistance to Papaya ringspot virus-type W in melon

Papaya ringspot virus‐type W (PRSV‐W) is the most prevalent and important viral pathogen of cucurbits in Brazil. It can be effectively controlled by the incorporation of genetic resistance into susceptible melon cultivars. The present study identified amplified fragment length polymorphic (AFLP) markers linked to the PRSV‐W resistance Prv¹ allele. The susceptible yellow‐fleshed melon‐breeding line AF426^prv1 and its nearly isogenic‐resistant line AF426^Prv1, which carries the Prv¹ allele resident in the Indian cantaloupe U.S. Plant Introduction (PI) 180280, were screened for AFLP marker polymorphisms. Of 30 251 AFLP loci, only three were polymorphic between the nearly isogenic lines. Segregation analyses for these three polymorphic markers and the Prv¹ allele using a BC₁ population of 197 plants indicated close linkage (0.5% recombination frequency) between marker EK190 (HindIII‐CGA and MseI‐GTG; 190 bp) and Prv¹. Thus, EK190 might be a useful marker in breeding programmes aiming to develop melon cultivars resistant to PRSV‐W. The other two markers are closely linked to each other, but distantly linked to Prv¹.     

Inheritance of angular leaf spot resistance in common bean line BAT 332 and identification of RAPD markers linked to the resistance gene

The existence of genetic variability for angular leaf spot (ALS) resistance in the common bean germplasm allows the development of breeding lines resistant to this disease. The BAT 332 line is an important resistance source to common bean ALS. In this work we determined the inheritance pattern and identified RAPD markers linked to a resistance gene present in BAT 332. Populations F₁, F₂,BCs and BCr derived from crosses between BAT 332 and cultivar Rudá were used. Rudá is a commercial cultivar with carioca type grains and susceptible to ALS. The resistance of BAT 332 to race 61.41 of the pathogen was confirmed. Segregation analysis of the plants indicated that a single dominant gene confers resistance. For identification of RAPD markers linked to the resistance gene, bulk segregant analysis (BSA) was used. Two RAPD markers,OPAA07₉₅₀ and OPAO12₉₅₀, linked in coupling phase at 5.10 and 5.83 cM of this gene, respectively, were identified. These molecular markers are important for common bean breeders and geneticists as source of genetic information and for marker assisted selection in breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

转基因抗虫棉Bt基因的遗传连锁分析

对中美两国所获得的转基因抗虫棉品种GK— 1 2、新棉 33B分别进行了 Bt基因的连锁测验。分析表明两个品种的试验结果相似 ,Bt基因未整合在棉花第 I、II、III、IV、V、VI、VII、IX、X、XI、XII、XIII、XVII连锁群及 cu、pg、gl1等基因所涉及的染色体上。阐明了 Bt基因染色体图谱定位的复杂性 ,并提出以原位杂交技术实现 Bt基因在棉花染色体组上的物理标图     

Immigrants Doing Business in a Mid‐sized Canadian City: Challenges,Opportunities, and Local Strategies in Kelowna,British Columbia

Lacking a tradition of settling immigrants and the appropriate infrastructure to integrate them, small‐ and medium‐sized cities often face the challenge of attracting and retaining immigrants. Using a mixed methods approach, this study compares the experiences of immigrant and non‐immigrant entrepreneurs in a mid‐sized Canadian city, Kelowna, British Columbia. A survey reveals different experiences between these two groups, with immigrants facing more challenges. In the absence of institutionally complete communities or strong ethnic economies, immigrants do not rely extensively on their own community resources, an element considered instrumental for immigrant business development in large cities. Compared to non‐immigrants, immigrant entrepreneurs have a more optimistic outlook on doing business in Kelowna; this is encouraging for a city trying hard to attract immigrant investment. Key informants recommended transforming the city into a more welcoming community, establishing appropriate support infrastructure, and removing potential institutional offsets. This paper adds new theoretical insights to the literature on immigrant entrepreneurship; all socio‐cultural, political‐institutional, and economic‐structural considerations are embedded in geography. The findings also have implications for growth strategies in small‐ and medium‐sized cities.     

Implications of early selection for grain colour on iron and zinc content and productivity of common bean

Brazilian consumers prefer beans of the beige grain colour. Common beans help supply dietary requirements for iron and zinc. The objectives of this study were (i) to determine whether early selection for grain colour affects the iron and zinc content and the grain yield in common beans and (ii) if an association between these characteristics was found, to obtain lines of carioca‐type grains with a high iron and zinc content and good grain yield. We evaluated 96 F_3:4, F_3:5 and F_3:6 progeny at two locations for iron and zinc content and grain yield. We selected 48 progeny for grain colour and chose 48 others at random. We found that early selection for grain colour does not affect the zinc content and grain yield. A positive and high association was found between iron and zinc content, and both iron and zinc content were slightly negatively correlated with grain yield. It is possible to obtain common bean lines combining a high iron and zinc content with good grain yield as long as a selection index is used.     

Gene flow in common bean (Phaseolus vulgaris L.)

This study was conducted in Brazil in order to assess the potential risk posed by gene escape from transgenic into non-transgenic plants and wild populations. A new methodology was applied to evaluate the gene flow between common bean cultivars, by means of a specially delineated experiment in two stages. The first stage consisted of the planting of one cultivar with violet flowers (BB) as pollen source (‘Diamante Negro’), and a receiver (‘Talismã’) with white flowers (bb), at different distances. The source was sown in the center of the area. The pollen receiver cultivar was sown, in concentrical squares around it. At maturity, the rows were sampled at varied distances from the source in the four cardinal directions. In the second stage, the sampled seeds of the previous stage were sown, and the percentage of outcrossing was evaluated during flowering through the presence of violet flowers (Bb). The highest frequency of natural hybrids, 0.136%, occurred at a distance of 0.5 m between the cultivars. The natural outcrossing rate was practically zero beyond a distance of 3.25 m.     

Plant nutrients in a degraded soil treated with water treatment sludge and cultivated with grasses and leguminous plants

The objective of this work was to evaluate rates for applications of water treatment sludge (WTS) as a nutrient source for grasses and leguminous plants cropped in a soil degraded by tin mining in the Amazon Region (Natural Forest of Jamari, Rondonia State, Brazil). The treatments consisted of three rates of nitrogen supplied by WTS (100, 150 and 200 mg kg⁻¹ soil), five combinations of plants, two controls (absolute control, without fertilization; and chemical control, soil+lime+chemical fertilizers). WTS modified the contents of macro and micronutrients in the degraded soil, but it was not, as used in the present study, sufficient for the rehabilitation of the degraded area.     

Influence of soil and host plant crop on the genetic diversity of Azospirillum amazonense isolates

The genetic structure of Azospirillum amazonense populations isolated from the rhizosphere soil and washed and surface-sterilised roots of rice, maize and sorghum plants, cropped simultaneously in two different soils (clay loam and sandy loam) was characterised. Genetic diversity was measured by restriction fragment length polymorphism of the amplified 16S–23S rDNA intergenic spacer region (RISA-RFLP) and cluster analysis. Four genetically distinct clusters of isolates were observed with 78% similarity, suggesting that the A. amazonense population was heterogeneous at the strain level regardless of the soil type or host plant. Analysis of molecular variance (AMOVA) demonstrated that the host plant had a highly significant selective effect on the genetic structure of this species, especially on those isolates intimately associated with them, but also to a lesser extent on isolates from the rhizosphere and washed roots. The soil type also had a highly significant selective effect on A. amazonense genetic diversity, especially for those isolates from the rhizosphere soil. The selective effect of the soil type combined with that of the host plant suggests that environmental factors, such as soil texture and composition of exudates provided by C₃ or C₄ plants, play major roles in the overall genetic structure of A. amazonense populations associated with these cereals.