抑制肠道气呼吸大鳞副泥鳅主要呼吸器官的组织病理

为了阐明肠道气呼吸对泥鳅的生理作用,本研究通过抑制大鳞副泥鳅肠道气呼吸,探究其主要呼吸器官的组织病理变化。结果显示,被抑制肠道气呼吸的大鳞副泥鳅通常在1周左右死亡。当被抑制肠道气呼吸的大鳞副泥鳅出现垂死时,采集对照组和实验组的鳃、皮肤、前肠、中肠、后肠以及直肠进行苏木素—伊红(H.E)染色、阿利新蓝—高碘酸雪夫氏(AB-PAS)染色组织切片观察和扫描电镜观察,主要的病理变化:①H.E染色结果显示实验组大鳞副泥鳅鳃丝末端充血,背部皮肤表皮层的毛细血管收缩并减少,且真皮层细胞呈畸形,前肠黏膜褶膨大,后肠浆膜层有血红细胞渗出,后肠、直肠结缔组织显著增厚;②AB-PAS染色结果显示,实验组大鳞副泥鳅鳃、背部皮肤、后肠、直肠组织中嗜酸性空泡细胞均增多,前肠和中肠固有层酸性黏蛋白含量增多,黏膜下层中性黏蛋白含量减少;③扫描电镜结果显示,实验组大鳞副泥鳅鳃丝鳃小片表面皱缩,表皮受损脱落,背部皮肤表面分泌孔增加,中肠内腔表面突起增多,后肠和直肠絮状颗粒增多。研究表明,抑制大鳞副泥鳅肠道气呼吸会引发其主要呼吸器官上皮组织出现黏液细胞增多、血红细胞溢出等病理变化,甚至导致机体死亡,由此可知,肠道气呼吸行为是大鳞副泥鳅的必要生理活动。本研究将为大鳞副泥鳅的健康养殖及幼苗培育提供新的参考。     

Expression and functional characterization of glutamine synthetase from giant freshwater prawn (Macrobrachium rosenbergii) under osmotic stress

The freshwater prawn, Macrobrachium rosenbergii naturally lives in the freshwater, though it migrates to the brackish water environment during spawning that claimed to be resistant on a broad range of saline fluxes. However, little is known about the osmoregulatory patterns and the effect of an enzyme glutamine synthetase (GS) in M. rosenbergii under stress. Here, we described the identification and functional characterization of GS from M. rosenbergii (Mr‐GS) at molecular and protein levels. The identified Mr‐GS was comprised of 361 amino acids that phylogenetically shared the highest identity with other crustaceans and predicted to contain Gln‐synt_C and Gln‐synt_N domains at the respective terminal regions. Tissue distribution analysis in M. rosenbergii revealed that the Mr‐GS was highly expressed in muscle, and commonly existed in other examined tissues in the following order gills > heart > stomach > brain > haemolymph. Whereas, the mRNA of Mr‐GS was significantly up‐regulated in the muscle and gill tissues following challenges with either hyper (0 → 13‰), or hypo (13 → 0‰) osmotic stress at 3, 6 and 12 hr. Furthermore, the level of Glutamine concentration was positively correlated with the GS mRNA and protein expression patterns in hyper‐osmotic stress, whereas in hypo‐osmotic stress a slight decrease in the gills and maintained a level in the muscle tissues at 3, 6 and 12 hr post‐treatments. Our findings suggest that Mr‐GS potentially exhibited the osmoregulation responses in the gill and muscle tissues of M. rosenbergii throughout the time of osmotic stress, which will benefit for future study on osmoregulation.     

Use of acoustic testing to detect decay and sort western juniper for modulus of elasticity and modulus of rupture

While wood has numerous attributes that make it an excellent material for many uses, its properties can also vary widely according to wood species and even within the same species. Wood used in structural applications is categorized into classes. For many wood products, these classes or grades are based upon visual assessments that account for grain characteristics along with natural defects such as knots or splits. These approaches are simple, but also limit the potential for identifying products based upon actual material properties. One alternative is to use acoustic tests to estimate modulus of elasticity and then correlate these values to actual material properties. The potential for using acoustic tests to estimate wood properties was assessed with a prototype acoustic device (Metriguard Model 242) on western juniper (Juniperus occidentalis) posts that were then tested using a destructive bending test. These tests could allow the identification of decayed areas within a post if they were directly in the tested area, but predicted modulus of elasticity was poorly correlated with actual modulus of rupture (r^2?=?0.23). The correlation was improved by only considering those samples where the acoustic test was made through the same area where the test load was applied, but the relationship was still weak (r^2?=?0.33). Acoustic testing did appear to be able to identify unacceptably weak samples with minimal rejection of acceptable samples, suggesting that acoustic testing might be a useful sorting tool to improve the reliability of timbers.     

Highly specific assays to detect isolates of Pseudomonas syringae pv. actinidiae biovar 3 and Pseudomonas syringae pv. actinidifoliorum directly from plant material

Pseudomonas syringae pv. actinidiae (Psa) is responsible for bacterial canker of kiwifruit. Biovar 3 of Psa (Psa3) has been causing widespread damage to yellow‐ and green‐fleshed kiwifruit (Actinidia spp.) cultivars in all the major kiwifruit‐producing countries in the world. In some areas, including New Zealand, P. syringae pv. actinidifoliorum (Pfm), another bacterial pathogen of kiwifruit, was initially classified as a low virulence biovar of Psa. Ability to rapidly distinguish between these pathovars is vital to the management of bacterial canker. Whole genome sequencing (WGS) data were used to develop PCR assays to specifically detect Psa3 and Pfm from field‐collected material without the need to culture bacteria. Genomic data from 36 strains of Psa, Pfm or related isolates enabled identification of areas of genomic variation suitable for primer design. The developed assays were tested on 147 non‐target bacterial species including strains likely to be found in kiwifruit orchards. A number of assays did not proceed because although they were able to discriminate between the different Psa biovars and Pfm, they also produced amplicons from other unrelated bacteria. This could have resulted in false positives from environmental samples, and demonstrates the care that is required when applying assays devised for pure cultures to field‐collected samples. The strategy described here for developing assays for distinguishing strains of closely related pathogens could be applied to other diseases with characteristics similar to Psa.     

Discovery of a sooty mould scavenging beetle, <Emphasis Type="Italic">Leiochrinus nilgirianus</Emphasis> Kaszab (Coleoptera: Tenebrionidae) on coconut palms infested by the invasive rugose spiralling whitefly, <Emphasis Type="Italic">Aleurodicus rugioperculatus</Emphasis> Martin (Hemiptera: Aleyrodidae)

Scavenging action of Leiochrinus nilgirianus Kaszab (Coleoptera: Tenebrionidae) on sooty mould deposition on coconut palms due to heavy honeydew production by the invasive rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae), is reported for the first time from Kerala, India. Adult beetles, averaging 2.07?±?0.9 / leaflet, with a maximum of five beetles per leaflet, and immature stages were generally confined to the abaxial of the palm leaves during daytime, but were found feeding on sooty mould during morning hours in damp conditions. The specially aided adaptive leg features of L. nilgirianus with bristle-like hairs on the undersurface of tarsomeres probably aid in proper adhesion on sooty mould laden plant surface and well developed tarsal claws that perhaps assist swift movement on fungus-laden leaflets. On an average one adult beetle could clear 1–2 mm² sooty mould laden area in a period of one minute. In situ habitat conservation of L. nilgirianus would help to reduce the sooty mould at no cost in the most natural and eco-friendly manner avoiding chemical management options and other expensive methods.     

Establishing Soil Silicon Test Procedure and Critical Silicon Level for Rice in Louisiana Soils

Calibration of crop responses to applied silicon (Si) serves as a basis for developing Si fertilizer recommendation guidelines. A greenhouse experiment was set up in a randomized complete block design with five replications, two sources of Si (wollastonite and slag) and four Si rates (0, 170, 340 and 680 kg ha^?1) to calibrate plant-available Si for growing rice in Louisiana soils. Silicon concentrations were determined in soils using seven different extraction procedures. Based on a quadratic model (p < 0.05), the estimated soil Si critical level using 0.01 M calcium chloride (CaCl₂) for Sharkey clay soil was 110 mg kg^?1 while for Crowley silt loam and Commerce silt loam, levels were 37 and 43 mg kg^?1, respectively. These results suggest that suitability of an extractant that gives the best estimate of plant-available Si could considerably depend on soil type and it is unlikely that there is a universal extractant for all soils.     

Agronomic evaluation of mulching and iron nutrition on productivity,nutrient uptake,iron use efficiency and economics of aerobic rice-wheat cropping system

Field experiments were carried out during rainy (kharif) and winter (rabi) seasons (June–April) of 2008–2010 at Indian Agricultural Research Institute (IARI), New Delhi, to study the productivity, nutrients uptake, iron (Fe) use-efficiency and economics of aerobic rice-wheat cropping system as influenced by mulching and Fe nutrition. The highest yield attributes, grain and straw yields (5.41 tonnes ha^?1 and 6.56 tonnes ha^?1, respectively) and nutrient uptake in rice was recorded with transplanted and puddled rice (TPR) followed by aerobic rice with Sesbania aculeata mulch. However, residual effect of aerobic rice with wheat straw mulch was more pronounced on yield attributes, grain and straw yields (4.20 and 6.70 tonnes ha^?1, respectively) and nutrient uptake in succeeding wheat and remained at par with aerobic rice with Sesbania mulch. Application of iron sulfate (FeSO₄) at 50 kg ha^?1 + 2 foliar sprays of 2% FeSO₄ was found to be the best in terms of all the yield attributes, grain and straw yield (5.09 and 6.17 tonnes ha^?1, respectively) and nutrient uptake and remained at par with 3 foliar sprays of 2% FeSO₄. Although residual effect of iron application failed to increase the yield attributes, yield and nutrient uptake nitrogen, phosphorus and potassium (N, P, K) except Fe. The highest system productivity, nutrient uptake, gross returns, net returns, B: C ratio and lowest cost of cultivation were recorded with aerobic rice with wheat straw and Sesbania aculeata mulch. Application of FeSO₄ at 50 kg ha^?1 + two foliar sprays of 2% FeSO₄ was found better in respect of system productivity, nutrient uptake, gross returns, net returns, B:C ratio and cost of cultivation in aerobic rice-wheat cropping system. The Fe use efficiency values viz. partial factor productivity (kg grain kg^?1 Fe), agronomic efficiency (kg grain increased kg^?1 Fe applied), agrophysiological efficiency (kg grain kg^?1 Fe uptake), physiological efficiency (kg biomass kg^?1 Fe uptake), apparent recovery (%) utilization efficiency and harvest index (%) of applied Fe were significantly affected due to methods of rice production and various Fe nutrition treatments in aerobic rice and aerobic rice-wheat cropping system.     

Studies on structural integrity of polyester-cotton friction spun yarn by cycling extension test

Yarns and fabrics are subjected to a low level of stresses or strains of repetitive nature in processing and actual use which leads to breakage, permanent deformation, bagging and loss of useful life of the product. The ability of the spun yarns and fabrics to withstand such stresses depends upon their structural integrity. A structurally rigid yarn (i.e. yarns in which fibres are tightly bound) would behave more like an elastic solid and consume more energy during deformation as the constituent fibres have to be deformed. Once the strain is released, the recovered energy will also be more. On the other hand if the structural integrity of the same yarn is poor, fibres would easily slip during deformation and would consume much less energy. The recoverable energy also will be much less. The present investigation reports on the structural integrity of friction spun yarns in terms of energy loss or decay by employing cyclic extension test. It has been observed that friction spun yarns in which the core is immediately wrapped by long and strong polyester fibre layer make the structure strongest as polyester is expected to form tight wrappings. The decay in deformation energies during extension cycling depends upon sheath structure i.e. its composition and location of constituent fibres in sheath layers. With increase in core fibre %, the decay has been found to increase. However, the decay values discriminate more between core% differences than between sheath fibre layer arrangements.     

A high-throughput, low cost gel-based SNP assay for positional cloning and marker assisted breeding of useful genes in cereals

Several SNP (single nucleotide polymorphism) genotyping methods have been developed in the past most of which require sophisticated instrumentation and large initial investments. We describe here a high-throughput SSCP (single strand conformation polymorphism) system on our HEGS (high efficiency genome scanning) platform, which is simple, accurate, cost effective and requires neither restriction digestion of the amplification products nor elaborate post-PCR processing detection. Several parameters critical to SSCP analysis were optimized viz., gel matrix and concentration, gel running temperature, buffer composition, running conditions and PCR primer design so as to identify SNPs in amplicons ranging from 100 to 750 bp in size. A simple post-PCR processing system was developed using fluorescent dye for quick and easy detection of SNP polymorphism. HEGS-SSCP was also found to be useful in uncovering simple sequence repeat differences between different genotypes that differ by one or few di/tri nucleotide repeats. The practical utility of this system is illustrated with two successful efforts towards construction of high resolution linkage maps of a lesion mimic locus on chromosome 7 and a major quantitative trait locus conditioning field blast resistance on chromosome 4 in rice.