Genetic effective size,Ne, tracks density in a small freshwater cyprinid,Pecos bluntnose shiner (Notropis simus pecosensis)

Genetic monitoring tracks changes in measures of diversity including allelic richness, heterozygosity and genetic effective size over time, and has emerged as an important tool for understanding evolutionary consequences of population management. One proposed application of genetic monitoring has been to estimate abundance and its trajectory through time. Here, genetic monitoring was conducted across five consecutive year for the Pecos bluntnose shiner, a federally threatened minnow. Temporal changes in allele frequencies at seven microsatellite DNA loci were used to estimate variance effective size (N_eV) across adjacent years in the time series. Likewise, effective size was computed using the linkage disequilibrium method (N_eD) for each sample. Estimates of N_e were then compared to estimates of adult fish density obtained from traditional demographic monitoring. For Pecos bluntnose shiner, density (catch‐per‐unit‐effort), N_eV and N_eD were positively associated across this time series. Results for Pecos bluntnose shiner were compared to a related and ecologically similar species, the Rio Grande silvery minnow. In this species, density and N_eV were negatively associated, which suggested decoupling of abundance and effective size trajectories. Conversely, density and N_eD were positively associated. For Rio Grande silvery minnow, discrepancies among estimates of N_e and their relationships with adult fish density could be related to effects of high variance in reproductive success in the wild and/or effects of supplementation of the wild population with captive‐bred and reared fish. The efficacy of N_e as a predictor of density and abundance may depend on intrinsic population dynamics of the species and how these dynamics are influenced by the landscape features, management protocols and other factors.     

Australian Distribution of 17 Species of Fruit Flies (Diptera: Tephritidae) Caught in Cue Lure Traps in February 1994

We report the first widespread survey of tephritid fruit flies attempted in a single time period. 1,471 cue lure traps caught 17 species, and extensions to previously recorded geographical ranges were detected for seven of them: Bactrocera tryoni, B. neohumeralis, B. frauenfeldi, B. aeroginosa, Dacus absonifascies, D. aequalis and D. newmani. the traps also unexpectedly caught several B. cacuminata and also both males and females of Dirioxa pornia and Ceratitis capitata. the geographical variation in the relative abundance of B. tryoni and B. neohumeralis in the region of their co-occurrence was in substantial agreement with earlier estimates. the regional variation in abundance of B. tryoni in the eastern states was in accordance with the predictions of a published bioclimatic model. Furthermore, the spread of this species (expected from the model) to several locations in the Northern Territory is recorded here for the first time.     

Preservation of fresh edible cactus stems (<i>Opuntia ficus indica</i> Mill.) by modified atmosphere packaging

Cactus stems, the cladodes of Opuntia spp. cacti, are consumed in Mexico and other countries due to their fresh and herbaceous flavor, and because of their widely known nutraceutical benefits. In order to extend the postharvest life of this vegetable, the effect of a modified atmosphere packaging (MAP) was studied in cactus stems of the cultivar Atlixco stored at 4 ± 1 °C for 20 days under three types of atmospheres: (1) air (passive atmosphere), (2) 5 kPa O₂ + 4 kPa CO₂, and (3) N₂. During storage, the titratable acidity decreased and the color of cladodes became darker and less green; however, the 5 kPa O₂ + 4 kPa CO₂ atmosphere was able to preserve both quality characteristics. All modified atmospheres reduced weight loss (from 8 to <2%) and the symptoms of chilling injury, and this physiological disorder appeared earlier in controls than in MAP-stored cladodes. The levels of fermentation metabolites were low in all three evaluated atmospheres. Because of this, only cladodes stored under the N₂ atmosphere were selected for furthersensory analysis of the MAP effect on odor perception as evaluated by a trained panel. Results indicated that there was no detrimental effect (atypical odors) of MAP on this sensory characteristic. We conclude that cultivar Atlixco is suitable for preservation using MAP technology.     

白沙蒿粘液瘦果萌发中外切糖苷酶活动特性

白沙蒿(Artemisia sphaerocephala Krasch.)是中国西北沙区分布的多年生植物.瘦果遇湿后其粘液层开始膨胀.对其种子萌发不同阶段的种胚提取物中几种可能降解果皮外层粘液物质的外切糖苷酶进行了检测.结果表明:β-吡喃半乳糖苷酶在干种子中的活性很高,但是随着种子的吸涨而逐渐降低,在已萌发的种子中无法探测到.α和β-吡喃阿拉伯糖苷酶、β-吡喃葡萄糖苷酶以及β-吡喃甘露糖苷酶在种子萌发过程的胚提取物中也显示出了一些活性,但是这些活性在种胚外却无法探测到.所有胚提取物中的外切糖苷酶都无法降解果皮粘液物质.所有的证据都表明果皮外层的粘液物质无法在种子萌发的早期被水解.因此果皮粘液物质在干旱沙质条件下的生态功能被限制在吸收水分以及延长胚吸水的时间.