Some effects of off-road vehicles and sheep grazing on lizard populations in the mojave desert

The effects of two environmentally disruptive activities were determined using the numbers and biomass of lizards. Sheep grazing reduces ground cover necessary for some lizard species. The use of vehicles on the desert also eliminates vegetation and adversely affects lizard populations.     

热带地区时间序列土壤中伊利石类矿物的演化——P.Barré假设在热带地区土壤中也存在吗?

P.Barré等认为温带地区自然土壤中,由于植物根系将下层土壤中的钾和硅向上搬运,减缓了上层土壤中伊利石类矿物(混层伊利石/蒙皂石+伊利石)脱钾和脱硅过程,致使其长时间地存在较多的伊利石类矿物。本文旨在了解热带地区土壤中这一假设是否也存在,以海南琼北地区发育于由不同年代火山喷发形成的玄武岩所构成的时间序列土壤(1×104a,(9.0±2.0)×104a,(14.6±0.9)×104a,64×104a,(133±18)×104a,(181±8)×104a)为对象,利用X-射线衍射(XRD)技术分析了其黏土矿物的变化情况,结合土壤钾、硅、活性硅的分析结果,发现伊利石类矿物仅存在于(133±18)×104a以前的土壤中,表层土壤中钾和硅的含量高于下层的土壤,活性硅含量随成土年龄而降低。为此,我们认为:P.Barré假设在热带土壤形成发育过程中,在具有一定的生物复钾和复硅条件下,在成土初期也会存在,但最终会由于土壤强烈的脱钾和脱硅作用而逐步消失。     

Effects of tolazoline and yohimbine on xylazine-induced central nervous system depression, bradycardia, and tachypnea in sheep

We compared the ability of tolazoline and yohimbine to antagonize xylazine-induced central nervous system depression, bradycardia, and tachypnea in 9 ewes and 5 rams. Once a week for 3 weeks, each sheep received one IV treatment of 0.4 mg xylazine/kg, 0.4 mg xylazine/kg followed in 10 minutes by 2 mg tolazoline/kg, or 0.4 mg xylazine/kg followed in 10 minutes by 0.2 mg yohimbine/kg. The order of the 3 treatments in each sheep was randomized. Xylazine alone caused recumbency for 41.0 +/- 3.7 minutes (mean +/- SEM). Tolazoline and yohimbine shortened the xylazine-induced recumbency to 12.1 +/- 0.9 minutes and 18.1 +/- 1.5 minutes, respectively. Sheep given xylazine alone had head droop for 34.0 +/- 5.4 minutes after rising. Head drooping of sheep given tolazoline or yohimbine was reduced to 10.1 +/- 1.7 minutes and 14.2 +/- 1.7 minutes, respectively. Both tolazoline and yohimbine reversed the bradycardia and tachypnea that followed xylazine administration. No statistical differences in the rate and magnitude of the reversal were observed between the 2 drugs.     

A comparison of North American avian conservation priority ranking systems

The need to prioritize species based on their perceived endangerment has led to the development of systems for categorizing and assessing their degree of vulnerability. Systems with divergent biological and geographical scopes can result in conflicting lists of high-priority species, potentially confusing conservationists and hampering the efficient allocation of resources. To assess conservation priorities for North American birds, we compare three priority-setting systems; those of the International Union for the Conservation of Nature (IUCN), NatureServe, and Partners in Flight (PIF). We found highest correspondence among the three systems in the highest and lowest categories of the respective systems with lower levels of correspondence in intermediate categories. We suggest that this is because the systems, while using different formulations of criteria, are based on the major factors known to be correlated with extinction risk. The few examples of species listed as a high conservation priority by one group but not one or both of the others appear to be the result of differences in availability or interpretation of data. Better communication and collaboration among those responsible for compiling the priority lists for each system is needed.A primary difference among the systems was the total number of species identified as conservation priorities. IUCN identified the fewest species (47) and PIF the most (157). This difference is the result of differences in geographic and taxonomic scope of each system. However, when considered as the percent of the total number of taxa evaluated by each system, all systems identified approximately 20% of species as of conservation concern. To reconcile disparate lists, we urge that conservationists use a hierarchical approach that first considers species that meet thresholds for endangerment under global systems, followed by species considered most vulnerable relative to all continental biota.     

Risk Factors for Femoral Fracture after Canine Press‐Fit Cementless Total Hip Arthroplasty

Objective: To evaluate risk factors for femoral fracture after porous‐coated cementless total hip arthroplasty (THA). Study Design: Case series. Animals: Dogs (n=74) that had cementless THA (n=84). Methods: Medical records of dogs from 2 referral hospitals were reviewed for occurrence of postoperative femoral fracture. Patient and operative (age, breed, sex, weight, and canal flare index [CFI], indication for arthroplasty, intraoperative fissure, cerclage usage, and implant sizes) factors were analyzed. Assessment of implant positioning and canal fill was performed on immediate postoperative radiographs. Femoral fractures (n=11) were evaluated and compared with 73 cases without fracture that met the inclusion criteria. Results: Mean (±SEM) age was 7.30±0.69 years for dogs with, and 4.77±0.37 years for dogs without femoral fracture. Age was positively associated with fracture (P=.022). Mean (±SEM) CFI was 1.80±0.09 for dogs with, and 1.98±0.04 for dogs without fracture. CFI was negatively associated with fracture (P=.045). Body weight, intraoperative fissure, cerclage use, implant size, position, and canal fill did not influence the occurrence of femoral fracture. Conclusions: Older dogs and dogs with lower CFI may be at increased risk for femoral fracture after porous‐coated cementless THA. Clinical Relevance: Risk factors exist for femoral fracture after cementless THA using porous‐coated implants, and should be critically evaluated during the patient selection. These risks should be weighed against the benefits of the system, and measures to minimize femoral fracture in at‐risk patients studied.     

Using EM and VERIS technology to assess land suitability for orchard and vineyard development

Orchard and vineyard producers conduct preplant site evaluations to help prevent planting permanent tree and vine crops on lands where the crop will not perform to its highest potential or attain its full life expectancy. Physical soil characteristics within specific soil profiles and spatially throughout an orchard influence decisions on land preparation, irrigation system selection, horticultural choices, and nutrient management. Producers depend on soil surveys to help them understand the soil characteristics of the land and may be interested in technology that provides additional information. Electromagnetic induction (EM38) and four-probe soil resistance sensors (VERIS) are being used in combination with global positioning systems to map spatial variability of soils using apparent soil electrical conductivity (ECa). The hypothesis evaluated in this study is whether rapid, in situ, and relatively low-cost methods of measuring ECa (EM38 and VERIS) can effectively identify and map physical soil variability in non-saline soils. The supposition is that in non-saline soils, ECa levels will relate well to soil texture and water-holding capacity and can be used to map physical soil variability. In turn, the information can be used to guide decisions on preplant tillage, irrigation system design, water and nutritional management, and other horticultural considerations. Two sites in the Sacramento Valley were mapped each with EM38 and VERIS methods. Site-specific management zones were identified by each provider on ECa maps for each site, and then soil samples were collected by University of California researchers to verify these zones. Results showed that on non-saline soils, ECa measured with both EM38 and VERIS correlate with physical soil properties such as gravel, sand, silt, and clay content but the relationship between conductivity and these physical soil properties varied from moderately strong to weak. The strength of the correlation may be affected by several factors including how dominant soil texture is on conductivity relative to other soil properties and on methods of equipment operation, data analysis and interpretation. Overall, the commercial providers of ECa surveys in this study delivered reasonable levels of accuracy that were consistent with results reported in previous studies. At one site, an ECa map developed with VERIS provided more detail on physical soil variability to supplement published soil surveys and aided in the planning and development of a walnut orchard. At a second site, almond yield appeared to correlate well with distinctly different soil zones identified with EM38 mapping.     

Heat-Induced Fragmentation of the Maize Waxy Protein During Protein Extraction from Starch Granules

The starch granule of maize contains a characteristic set of tightly bound polypeptides. Granule-associated polypeptides are typically extracted from starch granules by heating starch granule suspensions at 90–100°C in a detergent such as SDS. Solubilized proteins are recovered by centrifugation and analyzed by gel electrophoresis. Previously identified tightly bound granule intrinsic proteins consist of the 85-kDa starch-branching enzyme IIb, the 76-kDa starch synthase I, and the 60-kD waxy (Wx) protein, also known as granule-bound starch synthase I. However, SDS extracts from starch granules of maize also contain a cluster of proteins ranging in mass between 47 and 32 kDa In this study, we analyzed this group of granule-associated proteins and found that each was recognized by the Wx antibody. A 15 amino acid N-terminal sequence from the 47-kDa polypeptide was identical to the predicted N-terminus of the Wx protein. Further analysis revealed that each immunoreactive polypeptide between 47 and 32 kDa was a heat-induced fragmentation product of the Wx protein. Conditions for the extraction of granule proteins were evaluated. Our results demonstrate that granule proteins are effectively released by mild extraction (10-min incubation at 72°C). Relative to the Wx protein, starch synthase I and starch branching enzyme IIb were less susceptible to thermal fragmentation. These results demonstrate that the 85-, 76-, and 60-kDa polypeptides are authentic granule-intrinsic proteins, and that the majority of polypeptides between 47 and 32 kDa are artifacts of high-temperature granule extraction procedures.     

Hydrothermal Assessment of Temporal Variability in Seedbed Microclimate

The microclimatic requirements for successful seedling establishment are much more restrictive than those required for adult plant survival. The purpose of the current study was to use hydrothermal germination models and a soil energy and water flux model to evaluate intra- and interannual variability in seedbed microclimate relative to potential germination response of six perennial grasses and cheatgrass. We used a 44-yr weather record to parameterize a seedbed microclimate model for estimation of hourly temperature and moisture at seeding depth for a sandy loam soil type at the Orchard Field Test Site in southwestern Ada County, Idaho. Hydrothermal germination response was measured in the laboratory for two seed lots of cheatgrass (Bromus tectorum L.), four seed lots of bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] Löve), three seed lots of bottlebrush squirreltail (Elymus elymoides [Raf] Swezey), and one seed lot each of Sandberg bluegrass (Poa secunda J. Presl.), big squirreltail (Elymus multisetus [J.G. Smith] M.E. Jones), thickspike wheatgrass (Elymus lanceolatus [Scribn. And J.G. Smith] Gould) and Idaho fescue (Festuca idahoensis Elmer). Germination response models were developed to estimate potential germination rate for 13 subpopulations of each seed lot for every hour of the 44-yr simulation. Seedbed microclimate was assessed seasonally and for each day, month, and year, and germination rate-sum estimates integrated for a numerical index of relative site favorability for germination for each time period. The rate-sum favorability index showed a consistent pattern among seed lots for different years, and provides a relatively sensitive indicator of annual and seasonal variability in seedbed microclimate. This index could be used with field data to define minimum weather thresholds for successful establishment of alternative plant materials, in conjunction with weather forecast models for making restoration and fire-rehabilitation management decisions in the fall season, for evaluation of potential climate-change impacts on plant community trajectories, and in optimization schemes for selecting among alternative restoration/rehabilitation management scenarios.