SCINTIGRAPHIC EVALUATION OF THE STIFLE IN NORMAL HORSES AND HORSES WITH FORELIMB LAMENESS

We tested the hypotheses that mature horses without lameness have a repeatable radiopharmaceutical uptake pattern in the stifle, which is bilaterally symmetric; immature horses have a different radiopharmaceutical uptake pattern; and forelimb lameness alters the radiopharmaceutical uptake pattern in the stifle. The objectives of the study were to describe the normal radiopharmaceutical uptake patterns using region of interest (ROI) analysis; to compare uptake patterns between left and right stifles of the same horse and between mature and immature horses; to compare radiopharmaceutical uptake in mature normal horses with those with forelimb lameness. Lateral scintigraphic images of the stifle from 51 horses aged 2-16 years were evaluated using seven ROIs and a reference site (midfemur). After subtraction of a background count, ratios between the mean counts per pixel for each ROI to the reference site were calculated. There was a repeatable radiopharmaceutical uptake pattern in mature normal horses that was bilaterally symmetrical. The caudoproximal aspect of the tibia and the patella had the highest ratios. Radiopharmaceutical uptake patterns in horses with forelimb lameness were not significantly different. Immature normal horses had a different symmetric pattern, with greatest radiopharmaceutical uptake ratios in the caudoproximal aspect of the tibia and the tibial crest. It was concluded that there are symmetric, repeatable radiopharmaceutical uptake patterns in both immature and mature horses, which are not altered by forelimb lameness.     

On the magnitude and dynamics of eddy covariance system residual energy (energy balance closure error) in subsurface drip-irrigated maize field during growing and non-growing (dormant) seasons

We investigated the magnitude and dynamics of the eddy covariance system (ECS) residual energy (energy balance closure error) for a subsurface drip-irrigated maize (Zea mays L.) field in 2005 and 2006 growing and non-growing (dormant) seasons. The corrections for coordinate rotation, oxygen, frequency, and Webb–Pearman–Leuning corrections improved the slope of the total convective energy (latent heat + sensible heat) with respect to the net available energy (from 0.68 to 0.84), but the data filtering (for horizontal and frictional wind speeds higher than 2 m s^?1 and lower than 0.2 m s^?1) had little effect on the slope. Also, the number of data points available for the analyses was reduced by 53 % after filtering. Overall, the daytime residual energy varied between ?100 and 200 W m^?2 during the dormant seasons and between ?500 and 600 W m^?2 during the growing seasons. Most of the nighttime residual energy ranged within ±40 W m^?2 during the calendar year in 2005 and within ?60 and 20 W m^?2 in 2006. During nighttime, the total convective energy is vertically distributed with respect to (R _n ? G), indicating that the total convective energy is independent of the variations in (R _n ? G). Secondly, it was observed that nighttime residual energy did not show any seasonal variation patterns throughout the two consecutive years and confined mostly within a narrow range of ±40 W m^?2, showing no dependency on seasonal changes in surface conditions. The maximum variation in residual energy was usually around frictional wind speed of 0.3–0.5 m s^?1 (varying between ?150 and 300 W m^?2) and then decreasing to a range of ±100 W m^?2 at higher frictional wind speeds. On average, the residual energy decreased by about 33 W m^?2 (after the intercept) for every 1.0 m s^?1 increase in frictional wind speed, whereas the residual energy decreased by about 4 W m^?2 (after the intercept) for every 1.0 m s^?1 increase in horizontal wind speed. Similar diurnal residual energy distribution patterns, with different magnitudes, were observed during growing and dormant seasons. Even though a slight decrease in residual energy was observed with increase in leaf area index (LAI) in both growing seasons, LAI did not have considerable influence on the seasonal variation in the residual energy. The residual energy was also evaluated by separating the data into morning and afternoon hours. We observed that the root-mean-squared difference value is slightly greater for the morning data than the afternoon, indicating greater residual energy in the morning hours due to weaker turbulent mixing than the afternoon. Overall, significant reduction in the available evapotranspiration data after applying a series of corrections possess challenges in terms of utilization of ECS for in-season irrigation management and crop water requirement determinations that needs to be further researched and addressed.     

Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate

Quantifying the local crop response to irrigation is important for establishing adequate irrigation management strategies. This study evaluated the effect of irrigation applied with subsurface drip irrigation on field corn (Zea mays L.) evapotranspiration (ETc), yield, water use efficiencies (WUE = yield/ETc, and IWUE = yield/irrigation), and dry matter production in the semiarid climate of west central Nebraska. Eight treatments were imposed with irrigation amounts ranging from 53 to 356 mm in 2005 and from 22 to 226 mm in 2006. A soil water balance approach (based on FAO-56) was used to estimate daily soil water and ETc. Treatments resulted in seasonal ETc of 580–663 mm and 466–656 mm in 2005 and 2006, respectively. Yields among treatments differed by as much as 22% in 2005 and 52% in 2006. In both seasons, irrigation significantly affected yields, which increased with irrigation up to a point where irrigation became excessive. Distinct relationships were obtained each season. Yields increased linearly with seasonal ETc (R² = 0.89) and ETc/ETp (R² = 0.87) (ETp = ETc with no water stress). The yield response factor (ky), which indicates the relative reduction in yield to relative reduction in ETc, averaged 1.58 over the two seasons. WUE increased non-linearly with seasonal ETc and with yield. WUE was more sensitive to irrigation during the drier 2006 season, compared with 2005. Both seasons, IWUE decreased sharply with irrigation. Irrigation significantly affected dry matter production and partitioning into the different plant components (grain, cob, and stover). On average, the grain accounted for the majority of the above-ground plant dry mass (≈59%), followed by the stover (≈33%) and the cob (≈8%). The dry mass of the plant and that of each plant component tended to increase with seasonal ETc. The good relationships obtained in the study between crop performance indicators and seasonal ETc demonstrate that accurate estimates of ETc on a daily and seasonal basis can be valuable for making tactical in-season irrigation management decisions and for strategic irrigation planning and management.     

The toxicity of Castanospermum australe seeds for cattle

Two calves given a mean of 16.1 g and 16.4 g ripe Castanospermum australe seeds/kg body weight daily for 13 and 16 days respectively developed haemorrhagic gastroenteritis. The first calf died. The second calf had mild myocardial degeneration and necrosis and mild nephrosis at necropsy. Two calves given a mean of 16.8 g unripe C. australe seeds/kg body weight daily for 18 days remained clinically normal and had mild gastritis at necropsy. The activity of alpha-glucosidase was reduced in the mononuclear cells of peripheral blood and in skeletal muscle. This was attributed to the presence of the indolizidine alkaloid, castanospermine, in the seeds. The toxin causing the gastroenteritis and other lesions is unknown.     

The first case of genetically confirmed monozygotic twinning in the dog

Monozygotic twinning has not previously been genetically confirmed in the dog. This case report describes the finding of two viable male monozygotic foetuses within one placental site during caesarean section. Their umbilical cords attached to a single placenta. Genetic profiling using a total of 38 microsatellite markers, as well as amelogenin and SRY for sex determination, revealed identical DNA profiles, whether derived from blood or tissue (buccal swabs) samples. To the best of our knowledge, this is the first report of monozygotic twinning in the dog confirmed using DNA profiling.     

水稻RIL群体高密度遗传图谱的构建及苗期耐热性QTL定位

【目的】 随着全球气候变暖,高温严重威胁粮食安全,发掘耐热基因资源是培育耐高温新品种和消除高温危害最直接的绿色生态途径,也是阐明耐热生理生化和分子遗传机理的基础。【方法】 构建苗期耐热性鉴定评价方法,以热敏感品种周南稻和强耐热品种赣早籼58号杂交衍生的重组自交系（recombinant inbred lines,RIL）群体为研究材料,利用高通量测序技术对亲本和RIL群体进行全基因组测序;依据171个家系的基因型数据,利用滑动窗口法将SNP信息转换成Bin基因型,预测染色体上的重组断点,构建RIL群体高密度BinMap遗传图谱,结合耐热表型数据,运用QTL IciMapping软件完备复合区间ICIM的作图方法,进行高温胁迫下幼苗存活率和耐热等级QTL分析。【结果】 构建了一张包含3 321个Bin标记高密度遗传图谱,各染色体Bin标记数为159—400个,标记间平均物理距离为106 kb;利用逐步高温胁迫方式鉴定亲本和RIL家系幼苗耐热表型,高温胁迫下,幼苗存活率和耐热等级存在极显著负相关性,且幼苗存活率与籼型基因频率存在显著正相关性,籼型基因频率越高,耐热性越好,RIL群体表型性状呈现双峰连续分布,苗期耐热性可能受少数几个主效QTL调控;共检测到12个苗期耐热性相关的QTL,其中,调控幼苗存活率和耐热等级的QTL分别有8和4个,幼苗存活率和耐热等级相关QTL存在遗传重叠现象,形成调控耐热性的主效QTL簇qHTS2、qHTS7和qHTS8,三者在调控苗期高温抗逆中具有重要作用,其中,qHTS7为新发现主效QTL,对增强苗期耐热性具有较强的功效。【结论】 构建了一张包含3 321个Bin标记的高密度分子遗传图谱,解析了耐热品种赣早籼58号苗期耐热基因,鉴定出3个苗期耐热调控关键QTL簇,发掘了一个新主效QTL簇qHTS7,基于高密度遗传图谱高效获取目标区段及候选基因,筛选出8个苗期耐热性调控的关键目标基因。     

SCINTIGRAPHIC EVALUATION OF THE PROXIMAL METACARPAL AND METATARSAL REGIONS IN CLINICALLY SOUND HORSES

In recent years, pain arising from the proximal metacarpal and metatarsal regions has become well recognized as a cause of lameness and various disease entities have been identified. However, our knowledge of normal patterns of radiopharmaceutical uptake is limited, making interpretation of images problematic. It is therefore important to characterize normal patterns of radiopharmaceutical uptake at specific sites to ensure valid interpretation of images in clinical cases with subtle lesions. The purpose of this study was to describe the pattern of radiopharmaceutical uptake in the proximal metacarpal and proximal metatarsal regions in clinically sound horses. Scintigraphic images from 64 clinically normal horses were evaluated. All the images were assessed subjectively. The lateral, dorsal, and plantar scintigraphic images were assessed qualitatively using horizontal line profiles through the proximal metacarpal and proximal metatarsal regions. Mean ratios of radiopharmaceutical uptake were calculated from three regions of interest sited over the proximal metacarpal and proximal metatarsal regions and a reference site. In 78% of forelimbs the peak of radiopharmaceutical activity was at the dorsal to central portion of the proximal metacarpal region. Seventy-five per cent of the dorsal plane profiles of activity were symmetrical, with the highest peak over the medial to central portion of the proximal metacarpal region. In 80% of hindlimb lateral images the peak radiopharmaceutical activity was at the central to plantar aspect of the proximal metatarsal region. All (100%) plantar image profiles of activity were symmetrical, with the highest peak being over the lateral portion of the proximal metatarsal region. There was no significant left and right variation between sites for mean ratios on the lateral and dorsal images of the proximal metacarpal region. However, using lateral images the mean ratios from all regions of the right proximal metatarsal were greater than left (dorsal P = 0.003, plantar P < 0.0001 and whole proximal metatarsal, P = 0.0006). There was no significant variation in mean ratios between left and right on plantar images. However, the mean ratio for the lateral proximal metatarsal region was significantly greater than for the medial proximal metatarsal regions (P < 0.0001). There was no significant effect of age. Left/right symmetry of radiopharmaceutical uptake was shown in the proximal metacarpal region. However, there was a significant difference between left and right proximal metatarsal regions. There was higher radiopharmaceutical uptake in the right proximal metatarsal region than the left, which agrees with previous studies of the tarsal and metatarsophalangeal joints. There were differences in the pattern of radiopharmaceutical uptake between the forelimbs and hindlimbs. In the forelimbs maximum radiopharmaceutical uptake was located at the dorsal to central portion of the proximal metacarpal region in the lateral image, with peak activity over the medial to central portion of the proximal metacarpal region on dorsal images. In the hindlimbs the maximum radiopharmaceutical uptake was at the central to plantar aspect of the proximal metatarsal region in the lateral image, with peak activity over the lateral portion of proximal metatarsal region on plantar images. The results of this study support the hypothesis that there would be a standard pattern of radiopharmaceutical uptake across the proximal metacarpal and l metatarsal regions, but the pattern of uptake observed would be different in the proximal metacarpal region compared with the proximal metatarsal region. There was left/right symmetry of radiopharmaceutical uptake in the proximal metacarpal region. However, there was a significant difference between left and right proximal metatarsal regions, with higher radiopharmaceutical uptake in the right. There was no variation of radiopharmaceutical uptake pattern with age.     

Diffuse Extreme-Ultraviolet Emission from the Coma Cluster: Evidence for Rapidly Cooling Gases at Submegakelvin Temperatures

The central region of the Coma cluster of galaxies was observed in the energy band from 0.065 to 0.245 kiloelectron volts by the Deep Survey telescope aboard the Extreme Ultraviolet Explorer. A diffuse emission halo of angular diameter approximately 30 arc minutes was detected. The extreme-ultraviolet (EUV) emission level exceeds that expected from the x-ray temperature gas in Coma. This halo suggests the presence of two more phases in the emitting gas, one at a temperature of approximately 2 x 10(6) kelvin and the other at approximately 8 x 10(5) kelvin. The latter phase cools rapidly and, in steady state, would have produced cold matter with a mass of approximately 10(14) solar masses within the EUV halo. Although a similar EUV enhancement was discovered in the Virgo cluster, this detection in Coma applies to a noncooling flow system.     

Stormy weather in galaxy clusters

Recent x-ray, optical, and radio observations coupled with particle and gas dynamics numerical simulations reveal an unexpectedly complex environment within clusters of galaxies, driven by ongoing accretion of matter from large-scale supercluster filaments. Mergers between clusters and continuous infall of dark matter and baryons from the cluster periphery produce long-lived "stormy weather" within the gaseous cluster atmosphere-shocks, turbulence, and winds of more than 1000 kilometers per second. This weather may be responsible for shaping a rich variety of extended radio sources, which in turn act as "barometers" and "anemometers" of cluster weather.