Sterols that modify moulting in insects

The development of insects is under the control of a steroid hormone, ecdysone. This paper reviews suicide substrate type inactivators designed to inhibit the biosynthesis of ecdysone. Several series of acetylenic derivatives of cholesterol were synthesized and their biological effects on the prothoracic glands of the locust were investigated in vitro, enabling structure-activity relationships to be studied. Information on the ability of brassinosteroids, a series of plant growth regulators, to inhibit ecdysteroid activities of insects is discussed as a precursor to a study of brassinosteroid ecdysone mimics.     

蛋白质激发子Hrip1对小麦黄矮病的诱抗作用

小麦黄矮病是由大麦黄矮病毒（barley yellow dwarf virus,BYDV）引起的一种小麦病毒病,其传播介体是小麦蚜虫,在小麦生产中造成巨大的经济损失。近年来,植物诱导抗性作为一种新兴的植物病虫害防治措施引起了广泛的关注。蛋白质激发子Hrip1可以激活多种植物的免疫防御反应诱导植物产生广谱抗性。本研究评价了Hrip1对小麦黄矮病的诱抗效果。用30 μg/mL的Hrip1溶液进行小麦浸种和幼苗喷雾,随后接种BYDV,接种后第14 d,Hrip1对小麦黄矮病控制效果在50%以上,接种后第21 d控制效果仍在30%以上。实时荧光定量PCR检测结果显示,在Hrip1处理的小麦幼苗体内,BYDV外壳蛋白mRNA的数量显著低于对照组;EPG结果显示,在Hrip1处理的小麦幼苗上,麦二叉蚜寻找叶片刺吸位点和韧皮部取食位点的时间增加。以上结果表明：Hrip1能够有效地抑制BYDV在小麦体内的增殖;影响传毒媒介麦二叉蚜的取食行为,抑制其传毒能力。此外,Hrip1处理小麦能有效缓解BYDV引起的叶片黄化和植株矮化的症状。因此,Hrip1可以作为生物诱导剂综合控制小麦黄矮病。     

Effects of no‐take area size and age of marine protected areas on fisheries yields: a meta‐analytical approach

Marine protected areas (MPAs) are often promoted as tools for biodiversity conservation as well as for fisheries management. Despite increasing evidence of their usefulness, questions remain regarding the optimal design of MPAs, in particular concerning their function as fisheries management tools, for which empirical studies are still lacking. Using 28 data sets from seven MPAs in Southern Europe, we developed a meta‐analytical approach to investigate the effects of protection on adjacent fisheries and asking how these effects are influenced by MPA size and age. Southern European MPAs showed clear effects on the surrounding fisheries, on the ‘catch per unit effort’ (CPUE) of target species, but especially on the CPUE of the marketable catch. These effects depended on the time of protection and on the size of the no‐take area. CPUE of both target species and the marketable catch increased gradually by 2–4% per year over a long time period (at least 30 years). The influence of the size of the no‐take area appeared to be more complex. The catch rates of the entire fishery in and around the MPA were higher when the no‐take areas were smaller. Conversely, catch rates of selected fisheries that were expected to benefit most from protection increased when the no‐take area was larger. Our results emphasize the importance of MPA size on its export functions and suggest that an adequate, often extended, time frame be used for the management and the evaluation of effectiveness of MPAs.     

Detection and characterization of a rhabdovirus causing mortality in black bullhead catfish,Ameiurus melas

This study fully describes a severe disease outbreak occurred in 2016 in black bullhead catfish farmed in Italy. Affected fish showed nervous clinical signs as well as emaciations and haemorrhagic petechiae on the skin at the fin bases, abdomen and gills. Viral isolation in cell culture allowed the subsequent identification of a rhabdovirus, tentatively named ictalurid rhabdovirus (IcRV), through electron microscopy, immunofluorescence and whole genome sequencing (WGS). The newly isolated virus, together with 14 additional viral strains stored in our repository and detected during similar mortality episodes in the period 1993–2016, was phylogenetically analysed on the basis of the nucleoprotein and the glycoprotein nucleotide and amino acid sequences. The genetic distances among Italian IcRV strains were also estimated. Our results show that all the IcRV strains belong to the genus Sprivivirus and are closely related to the tench rhabdovirus (TenRV). Italian catfish production is constantly decreasing, mainly due to viral infections, which include the newly characterized IcRV. Data presented in this work will assist to investigate the molecular epidemiology and the diffusive dynamics of this virus and to develop adequate surveillance activities.     

Phylogenetic analysis of bacterial communities in the shrimp and sea cucumber aquaculture environment in northern China by culturing and PCR–DGGE

In this study, we investigated the bacterial communities in the shrimp and sea cucumber culture environment, including shrimp ponds (SP), sea cucumber ponds (SCP), mixed-culture ponds (MCP) and the effluent channel (EC) in Qingdao, China. Bacteria cultivation showed that the counts of heterotrophic, nitrate-reducing and sulfate-reducing bacteria in the sediment of SP were higher than that in the sediment of SCP and MCP, varying between 8.7 × 10⁴ and 1.86 × 10⁶, 2.1 × 10⁴ and 1.1 × 10⁵, and 9.3 × 10¹ and 1.1 × 10⁴ CFU g^?1, respectively. In contrast, the counts of ammonium-oxidizing and nitrifying bacteria in the sediment of SP was lower than that in the sediment of SCP and MCP. Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA gene and dendrogram analyses showed that bacterial diversity in the mixed-culture environment was higher than that in the monocultures. The similarity of bacterial community between EC and SCP or MCP was higher than that between EC and SP. These results indicated that sea cucumber culture played a significant role in influencing the environmental bacterial communities that were composed mainly of Flavobacteriaceae (64.3%), Bacteriodetes (21%) and delta proteobacteria (14.7%), including the genera of Croceimarina, Lutibacter, Psychroserpens and so on. The results explained the benefit of sea cucumber culture in shrimp ponds at the level of microbial ecology.     

收获沙棘振动器试验研究

该项研究的核心是研制振动器,通过振动果枝的方式来收获沙棘果实。2003到2004年间,基于我们的试验研究结果显示,沙棘品种＂印度夏季＂通过用频率为40Hz,振幅为15mm,10s为一振动周期的果枝振动器可有效获得果实。利用这个参数的振动可以有效获得90%的果实,且对果枝的损害很小,从果枝上下来的叶片、芽及木枝的碎片也很少。在2003年进行了最原始的研究,2004年测试发现这种方法存在一定缺陷。发电机利用机轴进行来回的旋转运动,利用这个原理进行各种振幅试验,但这对果树各部分会产生大量的压力。用1.5kW的电机可以在车间及没有农业机械的土地上进行试验,但这个过程需要人工看护。最原始的方法效率不高且过程复杂。2005年进行了设备的改进,通过凸轮产生的振动来驱动液压马达。尽管这种方法使用时间还很短,但是它的振动功能还是非常显著的。如果选在最佳采摘季节收获果实,收获的果实品质最佳,同时对果树的伤害也是最小的。如果在每个季节采摘500株或是更少果树的果实,这种振动收获果实的方法是一种最佳选择。     

Effects of increased nitrogen supply on the lignification of poplar wood

The short-term influence of adequate and high nitrogen fertilization on poplar lignification was investigated. The high nitrogen supply decreased lignin staining in the newly formed secondary xylem, indicating that lignin deposition was affected. Acetyl bromide determinations gave a 9-10% decrease in lignin content; however, Klason lignin content was unchanged. Thioacidolysis showed that elevated N supply affected lignin structure such that there was a reduced frequency of lignin units involved in beta-O-4 bonds, a reduced syringyl/guaiacyl ratio, an increased frequency of p-hydroxyphenyl lignin units, more guaiacyl units with free phenolic groups, and more p-hydroxybenzoic acid ester-linked to poplar lignins. These features suggest that lignins from poplars grown under high N bear structural similarities to lignins formed during early stages of wood development. The findings also indicate that a gravitational stimulus inducing the formation of tension wood and high N availability lead to similar and additive effects on lignin content and structure.     

Using operating area size and adjacency constraints to mitigate the effects of harvesting activities on boreal caribou habitat

Context

Sustained timber harvesting conflicts with the long-term viability of boreal caribou (Rangifer tarandus caribou) populations. The spatial arrangement of harvest blocks in the landscape could mitigate the impact of logging on caribou populations. For the forest industry, however, these measures represent constraints that reduce the annual allowable cut (AAC).

Objective

Estimate the long-term impacts of spatial constraints to harvesting, applied alone or in combination, on AAC and boreal caribou populations.

Methods

We divided a 30,000 km² region into 20 harvest block sizes varying from 50 to 1000 km², and modeled the implementation of spatially explicit harvest schedule plans in combination with wildfire and caribou population dynamics. We then evaluated the probability of persistence of boreal caribou populations.

Results

The probability of maintaining an AAC target declined with increasing target AAC, increasing size of operating area, and increasing adjacency constraints. In contrast, the probability of maintaining caribou populations declined with increasing AAC, decreasing size of operating areas, and decreasing adjacency constraints. An increase in operating area size from 50 to 300 km² produced a considerable gain in AAC for all adjacency constraints.

Conclusions

Because adjacency constraints led only to a small increase in the probability of maintaining caribou populations, we recommend adopting less constraining landscape management actions, such as a 70-year period between two consecutive harvests in the same ~300-km² operating area.

     

Evaluation of cystatin C as an endogenous marker of glomerular filtration rate in dogs

Cystatin C is a cysteine protease inhibitor produced by all nucleated cells. It is freely filtered by the glomerulus and is unaffected by nonrenal factors such as inflammation and gender. Because of greater sensitivity and specificity, cystatin C has been proposed to replace creatinine as a marker of glomerular filtration rate (GFR) in humans. The aims of this study were to validate an automated assay in canine plasma and to evaluate the usefulness of cystatin C as a marker of GFR in dogs. Western blotting was used to demonstrate cross-reactivity of an anti-human cystatin C antibody. An immunoturbidimetric assay was used to detect cystatin C in 25 clinically healthy dogs and 25 dogs with renal failure. Mean cystatin C concentration in the healthy dogs and the dogs with renal failure was 1.08 +/- 0.16 mg/L and 4.37 +/- 1.79 mg/L respectively. Intra- and interassay variability was <5%. The assay was linear (r = .974) between 0.14 and 7.53 mg/L. Both cystatin C and creatinine concentrations were measured in banked, frozen serum from 20 remnant kidney model dogs and 10 volume-depleted dogs for which GFR measurements by exogenous creatinine clearance had been determined previously. In the remnant kidney model, cystatin C was better correlated with GFR than creatinine (r = .79 versus .54) but was less well correlated with GFR in volume-depleted dogs (r = .54 versus .95). GFR measurements were repeated in the remnant kidney model dogs 60 days after initial GFR measurements. At this time, cystatin C and creatinine concentrations correlated equally well with GFR (r = .891 versus .894, respectively). Cystatin C concentration is a reasonable alternative to creatinine for screening dogs with decreased GFR due to chronic renal failure.