广义估计方程在CT显示方法研究数据分析中的应用

目的:探讨广义估计方程在CT显示方法研究中的应用.方法:采用SAS软件的GENMOD过程,应用广义估计方程方法分析CT显示方法研究实例.结果:给出了广义估计方程SAS程序,并对参数估计和两两比较结果进行解释.结论:广义估计方程能有效的分析CT显示方法研究中反应变量为两分类或多分类的非独立数据.     

Heavy use of prophylactic antibiotics in aquaculture: a growing problem for human and animal health and for the environment

The accelerated growth of finfish aquaculture has resulted in a series of developments detrimental to the environment and human health. The latter is illustrated by the widespread and unrestricted use of prophylactic antibiotics in this industry, especially in developing countries, to forestall bacterial infections resulting from sanitary shortcomings in fish rearing. The use of a wide variety of antibiotics in large amounts, including non-biodegradable antibiotics useful in human medicine, ensures that they remain in the aquatic environment, exerting their selective pressure for long periods of time. This process has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase of antibiotic resistance in fish pathogens, in the transfer of these resistance determinants to bacteria of land animals and to human pathogens, and in alterations of the bacterial flora both in sediments and in the water column. The use of large amounts of antibiotics that have to be mixed with fish food also creates problems for industrial health and increases the opportunities for the presence of residual antibiotics in fish meat and fish products. Thus, it appears that global efforts are needed to promote more judicious use of prophylactic antibiotics in aquaculture as accumulating evidence indicates that unrestricted use is detrimental to fish, terrestrial animals, and human health and the environment.     

Local ecological impacts of regional biodiversity on reef fish assemblages

Aim We examined comparative data for cryptobenthic reef fishes to determine how variation in regional species richness relates to local species richness, abundance, and taxonomic and trophic composition, and to test whether systems with higher species richness exhibit finer habitat partitioning. Locations Lizard Island, Great Barrier Reef (GBR), Australia; Bahía de Loreto, Gulf of California (GoC), Mexico. Methods Cryptobenthic reef fish assemblages from four habitats (coral heads, rubble, and horizontal and vertical surfaces of boulders) were collected using clove oil. Differences in density, species richness and biomass were examined between regions and among habitats. Habitat associations were identified for each habitat/location based on multivariate ordination, and the statistical significance of patterns was tested using analysis of similarity (ANOSIM). In addition, the trophic group composition of the assemblages for both regions was examined. Results A total of 91 species in 20 families were recorded (GBR, 66 species; GoC, 25 species). Total and habitat species richness were higher on the GBR, whereas biomass was higher in the GoC. No difference in fish density between regions was found. Habitat division among assemblages was greater in the depauperate GoC. Only coral head associations proved to be distinctive on the GBR, whereas three sample groups were found in the GoC (coral heads, horizontal boulders and vertical boulders/rubble). Trophic composition in the two regions was markedly different, with omnivores dominating the GBR fauna and planktivores the GoC. Main conclusions A positive regional–local relationship in fish diversity was found between regions, but fish abundance in both regions remained similar. Contrary to expectations, habitat partitioning, at a community level, was greater in the depauperate GoC. Differences in trophic composition and patterns of habitat use appear to reflect the disparate history of the regions, whereas patterns of abundance may reflect the influence of fundamental relationships between size and abundance in communities. This study highlights the potential of reef faunas to conform to universal numerical trends while maintaining an ability to respond ecologically to local/evolutionary influences. The GoC fauna appears to be exceptionally vulnerable to natural and anthropogenic disturbance owing to the high numerical dominance of habitat‐specific species and to the limited potential for functional redundancy within the system.     

Induction of nitrate reductase, nitrite reductase, and glutamine synthetase isoforms in sunflower cotyledons as affected by nitrate, light, and plastid integrity

Summary We investigated the inducibility of nitrate reductase (NR; EC 1.6.6.1), nitrite reductase (NiR; EC 1.7.7.1), and glutamine synthetase (GS; EC 6.3.1.2) isoforms in cotyledons of 7-day-old seedlings of sunflower (Helianthus annuus L.) in relation to light, nitrogen source (NO ₃ ^– , NO ₂ ^– or NH ₄ ⁺ ), and the involvement of plastids. Nitrate was absolutely (and specifically) required for NR induction, and stimulated more effectively than NO ₂ ^– or NH ₄ ⁺ the synthesis of NiR and chloroplastic GS (GS₂) over the constitutive levels present in N-free-grown seedlings. In vivo inhibition of NR activity by tungsten application to seedlings and measurements of tissue NO ₃ ^– concentration indicate that NO ₃ ^– -dependent enzyme induction is elicited by NO ₃ ^– per se and not by a product of its assimilatory reduction, e.g., NO ₂ ^– or NH ₄ ⁺ . In the presence of NO ₃ ^– , light remarkably enhanced the appearance of NR, NiR, and GS₂, while the activity of the cytosolic GS isoform (GS₁) was adversely affected. Cycloheximide suppressed much more efficiently than chloramphenicol the light- and NO ₃ ^– -dependent increase of GS₂ activity, indicating that sunflower chloroplastic GS is synthesized on cytoplasmic 80S ribosomes. When the plastids were damaged by photooxidation in cotyledons made carotenoid-free by application of norflurazon, the positive action of light and NO ₃ ^– on the appearance of NR, NiR, and GS₂ isoform was greatly abolished. Therefore, it is suggested that intact chloroplasts are required for the inductive effect of light and NO ₃ ^– and/or for the accumulation of newly formed enzymes in the organelle.Abbreviations CAP chloramphenicol - CHX cycloheximide - GS glutamine synthetase - GS₁ cytosolic GS - GS₂ plastidic (chloroplastic) GS - NF norflurazon - NiR nitrite reductase - NR nitrate reductase     

The 3120 +1G-->A splicing mutation in CFTR is common in Brazilian cystic fibrosis patients.

Cystic fibrosis patients from Rio de Janeiro, Brazil, were screened for mutations in exons 11 and 16 of the cystic fibrosis transmembrane conductance regulator gene (CFTR) by a nonradioactive single-stranded conformational polymorphism (SSCP) analysis technique. This procedure was used to evaluate the undefined mutations in one or both alleles of 64 cystic fibrosis patients. Unusual SSCP profiles were investigated further by sequence analysis. Two patients were shown to carry the G542X mutation (exon 11) and five had the splicing mutation 3120+1G-->A(intron 16), one of them being homozygous for the mutation. This is the first report of the 3120+ IG-->A mutation in Brazil. where it appears to be a frequent disease-associated molecular alteration in the CFTR gene.     

Construction of long DNA molecules using long PCR-based fusion of several fragments simultaneously

A procedure for precise assembly of linear DNA constructs as long as 20 kb is proposed. The method, which we call long multiple fusion, has been used to assemble up to four fragments simultaneously (for a 10.8 kb final product), offering an additional improvement on the combination of long PCR and overlap extension PCR. The method is based on Pfu polymerase mix, which has a proofreading activity. We successfully assembled (and confirmed by sequencing) seven different linear constructs ranging from 3 to 20 kb, including two 20 kb products (from fragments of 11, 1.7 and 7.5 kb), two 10.8 kb constructs, and two constructs of 6.1 and 6.2 kb, respectively. Accuracy of the PCR fusion is greater than or equal to one error per 6.6 kb, which is consistent with the expected error rate of the PCR mix. The method is expected to facilitate various kinds of complex genetic engineering projects that require precise in-frame assembly of multiple fragments, such as somatic cell knockout in human cells or creation of whole genomes of viruses for vaccine research.     

CFTR haplotype distribution in the Brazilian Western Amazonian region

Two hundred twenty-one individuals from four groups located around the Brazilian town of Porto Velho, Rond?nia, were studied in relation to four sites located within or near the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The allele frequencies, when considered individually, do not depart markedly from frequencies obtained from other populations of mainly European descent. However, when haplotypes were estimated, two of the groups departed markedly from other Brazilian and non-Brazilian samples. This finding is probably related to the complex multiethnic origin of these groups.     

Biology of Triatoma flavida Neiva, 1911 (Hemiptera: Reduviidae) under laboratory conditions

The complete life cycle of Triatoma flavida, weekly fed on hens, was studied at 28+/-2 degrees C and 80+/-10% RH. Aspects related to hatching, life span, mortality and feeding behavior for each stage of its life cycle were evaluated. The hatching rate observed for 100 eggs was 93% with an average incubation period of 27.2 days. Sixty-two nymphs completed the cycle and the mean egg to adult development time was 230.4 days. Mean duration of 1st, 2nd, 3rd, 4th and 5th instar nymphs was 22.1, 25.3, 36.7, 49.7 and 69.4 days, respectively. The number of blood meals on each nymphal stage varied from 1 to 7. The mortality rate was 6.5% for NI, 23% for NIII and 7.5% for NV nymphs. Mean number of laid eggs per female was 283.1. Adult survival rates were 344.8 +/- 256.4 days for males and 285.3 +/- 201.8 days for females.