Geographical distribution and diversity of maize (<Emphasis Type="Italic">Zea mays</Emphasis> L. subsp. <Emphasis Type="Italic">mays</Emphasis>) races in Mexico

The center of origin of maize is in Mexico and maize diversity is very high in many parts of the country. Here we describe and analyze the geographic distribution and diversity of maize using a database of 18,176 georeferenced observations of maize races. The number of observations by race follows the common “hollow curve” distribution, with six races comprising 54 % of the records and 37 races only 10 %. Few races are widespread, and some have a highly localized distribution. The average maximum distance (D _max) between two records of the same race was 1169 km, but seven races had a D _max lower than 200 km. The average circular area range size (CA₂₅) was 51, but 14 races had a CA₂₅ lower than 10. Some races have very few observations but were found over a large area. These races may not be valid and their classification should be reviewed. Areas of high race richness and diversity are in mountainous northwest, south central, and southern Mexico in the states of Oaxaca, Jalisco, Michoacán and Chiapas. Six contiguous maize regions were defined using hierarchical clustering. Despite the high sample size, further sampling could improve estimates of race diversity in several regions.     

Tiptoeing between restoration and invasion: seed rain into natural gaps within a highly invaded relic forest in the Azores

The last remains of native laurel forest in the Azores are highly threatened by the spread of invasive plants. Because landslides are very frequent in these islands, conservation of native laurel forest requires knowledge of the patterns of bird-dispersed seed rain into forest gaps. We monitored 78 seed traps over 1 year to investigate (1) the role of perches in attracting avian dispersers into gaps, (2) temporal patterns in the dispersal of exotic and native seeds, (3) how seed rain affects vegetation establishment in gaps at different distances from the native forest and (4) whether the caloric content of fruits could explain the number of seeds dispersed. Perches were highly effective in concentrating avian seed dispersal. While some native fruits are produced all year-round, most exotic plants set fruits during the main peak of the native fruit production (August–November). Most seeds recovered from the traps were native, and native seed rain inside the native forest was higher than in gaps. However, deposition of exotic seeds was not affected by distance from native forest. Seed dispersal frequencies monitored by seed traps and by faecal analysis were correlated with each other, but not with fruit caloric content, suggesting that other factors are more important that the nutritional value in predicting avian fruit choice. Forest restoration activities should take into consideration that seed dispersal decreases sharply beyond 100 m from native forest and the attractive potential of perches to direct natural seed dispersal into forest gaps.     

育雏前期日粮中的核苷酸对雏鸡的促生长作用

雏鸡的第1周的饲料数量仅是上市鸡总饲料的3.5%,但是为了得到最适的生长性能,环境的管理和恰当的营养是关键.因为雏鸡和成年鸡不一样,雏鸡没有复杂的消化酶,所以不能很好的起到消化的作用.在育雏期的早期,雏鸡面临着最困难的生理过渡时期,也就是开产期日粮中复杂的碳水化合物、蛋白质、脂类替代了胚胎中脂类和蛋白质的营养来源.而且雏鸡的免疫系统发育不完全,免疫主要靠母源抗体.……     

Cysteine proteinases Fas1 and Fas2 are diagnostic markers for Fasciola hepatica infection in alpacas (Lama pacos)

Circulating antibody against Fasciola hepatica antigens was determined by enzyme-linked immunosorbent assay (ELISA) and immunoelectrophoresis in alpacas naturally exposed to F. hepatica. Serological assay parameters were established by using sera from eight infected animals and seven controls with no record of this parasitic infection. Excretory--secretory (ES-) products, Fas1- and Fas2-ELISA were used to survey 307 alpacas from a F. hepatica endemic area in the Peruvian Andes. Seroprevalence of F. hepatica infection varied from 56.7, 64.8 and 66.8% measured by Fas1-, Fas2- and ES-ELISA, respectively. The sensitivity for ES-ELISA was 95%, corresponding Fas1- and Fas2-ELISA sensitivity values were 90 and 95%. In this population, 7% of animals were positive for F. hepatica eggs in faeces, other parasites detected were Trichuris sp. (40%), Nematodirus sp. (34.6%), Lamanema sp. (12.8%) and Eimeria sp. (11.8%). The results show that F. hepatica infected animals elicit circulating antibodies against ES, Fas1 and Fas2. Fas2-ELISA may be proposed as a sensitive assay for the immunodiagnosis of fasciolosis in alpacas.     

A modelling approach to infer the effects of wind farms on landscape connectivity for bats

Little is known about the potentially disrupting effects of wind farms on the habitat connectivity of flying vertebrates at the landscape scale. We developed a regional-scale model to assess the wind farm impact on bat migration and commuting routes. The model was implemented for the bat Nyctalus leisleri in a region of central Italy currently undergoing considerable wind farm development. A Species Distribution Model (SDM) for N. leisleri was generated using the MaxEnt algorithm based on 47 presence records (reduced to 19 after the autocorrelation procedure) and 10 environmental variables derived from topographic and land cover maps. We used the SDM to create a map of connectivity using the software UNICOR to identify potential commuting corridors (PCCs). The incidence of each wind farm on bat flight corridors was assessed by overlaying the existing (380) and planned (195) turbine locations onto the PCCs. The SDM was statistically robust (AUC > 0.8). Most of the corridors were concentrated in the western part of the region, which hosts the largest suitable areas for the species; most of the existing (54 %) and planned (72 %) wind farms interfered with important corridors connecting the western and the eastern parts of the region. Our results provide key information on the impact of the wind farm industry on biodiversity on a regional scale. The novel approach adopted, based on SDM and connectivity analysis, could be easily extended to other flying vertebrates and landscapes and constitutes a promising planning tool necessary for harmonizing the development of renewable energy infrastructures with issues of biodiversity conservation.     

Rapid determination of inorganic and methyl mercury in fish

A method has been developed that uses a mixed solution of NaOH, NaCl and cysteine to digest fish. Inorganic Hg and MgHg were determined by cold vapor atomic absorption (CVAAS) using a selective reduction step with SnCl₂ and SnCL₂-solutions. Ethyl alcohol was satisfactorily used to prevent excessive foaming. Two optimum digestion procedures were established: (1) using a dry block heater at 90 °C for 1 hr and (2) overnight digestion at 25 to 30 °C. Differences between both were not significant (95%) in the range of 30 to 500 ng g^?1 Hg (II) and MeHg in fish. Reduction of the Hg signal due to matrix effects in different fish species was evaluated (95 to 60%). Oily fish, shrimp and lobsters gave the highest reduction. Internal calibration by addition of Hg standards are strongly recommended when exact determinations are needed. The detection limit obtained was near 10 ng g^?1. Signals were linear in the concentration range studied (30 to 500 ng g^?1). Accuracy of analyses was in the order of 5% or better, with a relative standard deviation of 5%. The method could be applied to other environmental matrices: hair, urine and blood, with some modifications.     

Prevalence and risk factors of mycobacterial infections in farm and trade cattle in southwestern Nigeria

We evaluated the prevalence of mycobacterial infections (i.e., Mycobacterium bovis and non-tuberculous mycobacteria [NTM]) and their associated risk factors among cattle herds and trade cattle in southwestern Nigeria. Through cross-sectional study design, cattle herds from three locations were screened using the single intradermal comparative cervical tuberculin test based on two diagnostic standards; more than 4 mm (? 4 mm) and more than 2 mm (? 2 mm) cut-off points. Abattoir study involved screening trade cattle for tuberculous lesions. Overall, 515 cattle from 45 herds were screened. Using >?4 mm, animal level and herd prevalence of 11.7 and 46.7% were recorded, respectively. Applying the ? 2 mm cut-off, animal level and herd prevalence increased to 31.1 and 60.0%, respectively. Significantly, using the ? 2 mm cut-off, cattle in medium size herds/extensive management system (OR?=?1.6; 95% CI 1.1–2.5) and Sokoto Gudali (OR?=?2.3; 95% CI 1.4–3.8) were more at risk of being positive reactors, while Rahaji (OR?=?0.3; 95% CI 0.1–0.7) breeds of cattle and cows in the peri-urban area (OR?=?0.4; 95% CI 0.2–0.9) were less at risk of being positive reactors. Again, M. avium reactor of 21.7% was observed. In the abattoir, 1797 cattle were examined with 126 lesions suggestive of tuberculosis (TB). Culture/molecular analyses confirmed 2.2% M. bovis and 0.9% NTM infections. Risk factors associated with bovine TB among trade cattle were sex (OR?=?4.0; 95% CI 1.2–13.5) and age (OR?=?0.3; 95% CI 0.1–0.9). We confirm 11.7% prevalence of mycobacterial infections among populations of cattle screened with breed and herd size being major risk factors.