近50年气候变化对塔拉滩草地荒漠化的影响

塔拉滩区地处共和盆地,20世纪80年代以后,该地区草地严重退化,沙漠化强烈发展等生态恶化问题十分突出。通过共和盆地近50a的气温、降水、大风、沙尘暴和草地蒸发力等气候因子的变化特征,分析了草地退化的主要原因,结果显示46a来仅气温呈现出明显的上升趋势,降水呈现微弱的增加趋势,蒸发量和草地蒸发力随时间呈现上升趋势。通过1987年、1996年两期TM卫星遥感影像解译和1994年、1999年两期沙漠化普查与监测,进一步表明共和盆地塔拉滩草地荒漠化正在扩展。塔拉滩草地荒漠化扩展是气候变化和人类活动共同胁迫的结果,不合理的人类活动对荒漠化发生与扩展起着加速、加剧作用。     

洞庭湖区湿地退化现状及保护对策

洞庭湖湿地是我国重要的淡水湖泊湿地之一,其生态环境对调蓄洪水、调节气候、涵养水源、净化水质、维护生物多样性等方面具有重要的作用。多年来由于人类不合理的开发利用,给湿地生态系统带来了负面影响,致使湿地严重退化。在分析洞庭湖区湿地退化现状及其原因的基础之上,提出了湿地保护与可持续利用的对策和措施。     

三樱椒生产中存在的问题及解决途径

三樱椒生产中存在品种退化、栽培管理技术不规范、病虫害严重、加工领域狭窄等问题，针对这些问题，提出应采取精选良种、提纯复优、科技化管理、病虫害综合防治、培植龙头加工企业等相应措施，拉长产业链条，实现多层次增值，推动产业化进程。     

无声的危机--荒漠化与草原退化

阐述了荒漠化与草原退化的概念，成因及相互关系，强调指出绿洲周围的“两化”，除过牧，过垦，过伐等因素外，主要是水资源减少所致；提出了以荒漠型，盐渍型，黑土滩型，毒杂草型等为代表的草原退化的主要类型，并认为荒漠化与草原退化是无声的危机，威胁着人们的生存与发展，而荒漠化危害首当其冲的是草原，要防治荒漠化首先要防止草原退化。     

我国北方草地的现状和可持续发展对策

草地是畜牧业生产的重要资源。目前,我国北方草地大面积退化,生产力下降,同时自我恢复功能降低或丧失等。本文阐明了北方草地退化的原因,提出了实现草地可持续发展的策略,认为只有将生态效益、经济效益和社会效益有机地结合起来才能科学地利用草地资源。     

Appearance and incidence of sacroiliac joint disease in ventrodorsal radiographs of the canine pelvis

Ventrodorsal (VD) radiographs of cadaveric pelves of large and giant breeds (n = 40) and of the corresponding bone specimens were made. Gross changes seen in the specimens were marked with metal wire or radiopaque paint to relate radiographic changes to the postmortem appearance of degenerative sacroiliac (SI) joint lesions. Two positioning techniques were used, resulting in two radiographs for each specimen. The techniques used were: (1) pulling the pelvic limbs caudally, with gentle traction producing a view of the sacrum in almost parallel alignment between the sacrum and the X-ray film (we have termed this a "central SI view") and (2) pulling the pelvic limbs caudally with greater traction than above, resulting in maximal inclination of the sacrum with respect to the X-ray film (we have termed this an "angled SI view"). Lesions of the supportive soft connective tissue could be imaged on the central and angled SI views, whereas angled SI views allowed better identification of lesions of the synovial SI joint. The insights gained in the above study were then used in a retrospective examination of 145 routine ventrodorsal radiographs of the pelvis (i.e., 290 sacroiliac joints) to determine the incidence of degenerative changes of the SI joint in large dogs. The lesions most commonly observed were calcification of the supportive soft connective tissue (n = 184/290), whereas lesions of the synovial SI joint were less frequent (n = 86/290). The degree of central or angled projection obtained in standard ventrodorsal radiographs was noted to be significantly (P < 0.05) associated with age, body conformation, anesthetic status, and the presence of spondylosis deformans at the lumbosacral junction. In contrast, SI joint disease and the gender of the animal did not affect the SI view achieved in VD radiographs.     

Abnormal dark-adapted ERG in cats heterozygous for a recessively inherited rod-cone degeneration

Purpose To study retinal function in cats homozygous and heterozygous for a recessively inherited rod‐cone degeneration. Methods Dark‐adapted electroretinograms (ERGs) were performed on early affected, heterozygous (ophthalmoscopically normal), and clinically normal, nonrelated cats. Responses to blue stimuli over a 3.9‐log unit range were recorded. Results Lower b‐wave amplitudes than normal were observed in heterozygotes and early affected cats. The amplitudes of the heterozygotes took an intermediate position between normal and early affected cats. Normalized amplitude/intensity data suggest a normal dynamic range in carriers. B‐wave implicit times in carriers were comparable to those of normal cats. Conclusions These results show that heterozygotes have an altered retinal function, although they are ophthalmoscopically normal. It is difficult to electrophysiologically differentiate heterozygotes from affected cats with the very early stage of retinal degeneration.     

Early retinopathy in the Bernese Mountain Dog in France: preliminary observations

The objective of the study was to describe a form of early retinopathy in the Bernese Mountain Dog in France. Sixty-two Bernese Mountain Dogs (38 males and 24 females), whose ages ranged from 2 months to 9 years, were examined over a period of 3 years. Visual behavior, pupillary light reflexes, menace responses and ocular fundi were evaluated in all animals. Electroretinography (ERG) was performed on six of the affected dogs after dark adaptation. Fluorescein angiography (FA) was performed on one affected dog. Whenever possible, the pedigrees of the affected dogs were evaluated. A histological examination of the retina was performed on one of the affected dogs. Eight dogs (seven males and one female) were diagnosed with retinopathy with an early onset of clinical signs. (Four dogs were aged between 3 months and 1 year, two dogs were aged 2 and 3.5 years, and one dog was 7 years old.) Night vision was impaired in most of the dogs. Retinopathy was characterized ophthalmoscopically by a bilateral, symmetrical horizontal zone of tapetal hyper-reflectivity adjacent to and above the optic disc, and sometimes by peri-papillary hyper-reflectivity. ERG changes included a reduction in b-wave amplitude varying from one case to another. Fluoroscein angiography demonstrated an ischemic-type alteration with epitheliopathy opposite the hyper-reflective zone. Pedigree examinations suggested a familial predisposition. The histological examination indicated photoreceptor degeneration that was more pronounced in the central tapetal zone. In France, retinopathy in the Bernese Mountain Dog involves an early retinal degeneration that produces specific manifestations of the ocular fundus, night visual impairment or blindness, and has familial transmission.     

Effects of hereditary retinal degeneration due to a CEP290 mutation on the feline pupillary light reflex

Objective To understand how progressive rod cone degeneration due to a mutation in CEP290 affects the pupillary light reflex (PLR) in domestic cats. Animals studied Domestic cats identified as either normal wildtype (WT; n = 6), or homozygous for the rdAc mutation in CEP290 and having early stage retinal degeneration (stage 2, S2; n = 4), or advanced retinal degeneration (S4; n = 6). Methods The effect of light on pupil size was measured over a series of 10‐s pulses of white and chromatic light in cats lightly sedated with medetomidine. Results In WT cats, the PLR was characterized by a pronounced initial constriction that rapidly re‐dilated during the stimulus (pupil escape), to a stable or sustained constriction. There was then a marked constriction at stimulus offset. Each component of the PLR was retained in affected cats, but with progressively reduced irradiance sensitivity from early to advanced retinal disease. Conclusions The PLR of cats had multiple phases, with a remarkably high‐amplitude ‘paradoxical’ off‐constriction even in the absence of retinal disease. In rdAc cats, reduced irradiance sensitivity was consistent with progressive loss of rod and cone function. Based on previously characterized retinal pathology, this suggests the visual streak of the retina has a proportionally large contribution to PLR input. These findings support the hypothesis that the efficacy of planned therapeutic trials can be determined by careful evaluation of the PLR in cats.     

Susceptibility to N-methyl-N-nitrosourea-induced retinal degeneration in different rat strains

To evaluate the potential role of genetic background in the susceptibility to retinal degeneration induced by N-methyl-N-nitrosourea (MNU), female rats of the Sprague-Dawley (SD), Long-Evans (LE) and Copenhagen (CH) strains were administered 50 mg/kg MNU or saline at 7 weeks of age. Retina morphology and morphometric analysis of all rats was performed 7 days after MNU administration. Atrophy of both the peripheral and central outer retina occurred in all rat strains exposed to MNU. Decreased photoreceptor cell ratio and increased retinal damage ratio were observed. The severities of the retinal atrophy were similar among all three rat strains. In conclusion, MNU-induced photoreceptor degeneration developed consistently in all three strains regardless of the absence (SD rats) or presence (LE and CH rats) of melanin in the retina, suggesting that genetic and melanin factors did not affect photoreceptor cell death after MNU.