Phylogeny and Biogeography of Cyanobacteria and Their Produced Toxins

Phylogeny is an evolutionary reconstruction of the past relationships of DNA or protein sequences and it can further be used as a tool to assess population structuring, genetic diversity and biogeographic patterns. In the microbial world, the concept that everything is everywhere is widely accepted. However, it is much debated whether microbes are easily dispersed globally or whether they, like many macro-organisms, have historical biogeographies. Biogeography can be defined as the science that documents the spatial and temporal distribution of a given taxa in the environment at local, regional and continental scales. Speciation, extinction and dispersal are proposed to explain the generation of biogeographic patterns. Cyanobacteria are a diverse group of microorganisms that inhabit a wide range of ecological niches and are well known for their toxic secondary metabolite production. Knowledge of the evolution and dispersal of these microorganisms is still limited, and further research to understand such topics is imperative. Here, we provide a compilation of the most relevant information regarding these issues to better understand the present state of the art as a platform for future studies, and we highlight examples of both phylogenetic and biogeographic studies in non-symbiotic cyanobacteria and cyanotoxins.     

武陵源茶树种质资源形态及显微结构研究

为了开发与利用武陵源白虎堂区茶树种质资源,通过实地和显微结构观测,对15个单株的形态和叶片进行了研究。结果表明:花的萼片均为绿色、无毛,萼片数在4~6片之间,以5片为主,占73.3%;花冠大小在2.6~5.0 cm之间;花柱开裂数2~3裂,3裂占80%;雌雄蕊相对高度等高率占73.3%;叶面积在9.64~65.22 cm2之间,叶片多为长椭圆形、披针形,叶面平,叶质软,叶尖渐尖,叶色深绿;栅栏组织1~2层,平均厚度105.21μm;海绵组织平均厚度227.28μm;栅海比0.6以上,抗寒性较强的有3株。     

Effect of solution and apparatus parameters on the morphology and size of electrosprayed PLGA microparticles

Because of a number of facilities, the Electrospray (ES) method is gaining ever-increasing popularity among researchers for producing nano-to-micron-sized particles. Microparticles (MPs) of poly lactic-co-glycolic acid (PLGA) were prepared by using the ES technique. The influence of both solution and apparatus parameters on the morphology, size, size distribution, and uniformity of produced MPs were investigated. Results of SEM images and calculations revealed that polymer concentration is a critical parameter in the ES system. In a semi-dilute moderately entangled regime, chain entanglement can easily occur. Solution flow rate is a key factor among apparatus parameters. Vapour pressure is a key parameter affecting MP morphology. The size of the particles tended to reduce with an increase in voltage. The needle gauge did not have an important impact on particle size. The role of the electric field changed at different collecting distances. Using a saturated combination of EtOH/PVA is an acceptable collecting medium for PLGA MPs. It is possible to produce uniform and spherical MPs by using chloroform as a solvent. However, a reduction in particle size is achievable by using a solvent of chloroform/DMF (90/10 w/w).     

The effects of a vegetarian and vegan diet on plasma and erythrocyte lipids

Vegetarians usually consume milk, cheese and eggs, whilst vegans consume a diet consisting entirely of plant foods. The protein in a vegan diet is therefore entirely of plant origin. The vegan diet also differs from that of vegetarians and omnivores in having a lower fat content, no cholesterol and a high proportion of short-chain polyunsaturated fatty acids, particularly linoleic acid. The diet of large numbers of people in the Third World is predominantly of plant origin and vegans are an excellent natural ‘experimental model’ for the study of the effects of such a diet on plasma and membrane lipids. The serum cholesterol and triglycerides were lower in vegans, but not in vegetarians, than in age-sex-matched omnivores. Vegan plasma phosphoglycerides contained a lower proportion of 16∶0 and 18∶1 fatty acids, but a higher proportion of 18∶2ω6. The proportion of the longer chain polyunsaturated fatty acids of the ω6 series tended to be higher and the differences were significant for 20∶2ω6, 20∶4ω6 and 22∶4ω6. The proportion of the fatty acids of the ω3 series were lower. Similar differences were found in the erythrocytes. The concentrations in vegetarians were intermediate between those of vegans and omnivores. It is concluded that a vegan diet may have some benefit in that it results in lower serum concentrations of cholesterol and triglycerides. The importance of the differences in membrane fatty acid. Vegetarians usually consume milk, cheese and eggs, whilst vegans, for a variety of reasons, consume a diet consisting only of unrefined cereal, legumes, nuts and vegetable and fruit products. The protein in a vegan diet is therefore solely of plant origin. The diet of vegans differs, however, from that of vegetarians and omnivores in respect of its lipid content, for not only is the total amount of lipid lower, but it contains no cholesterol or long chain polyunsaturated fatty acids, that is fatty acids with a carbon chain length of twenty carbon atoms or more. On the other hand, it contains a high proportion of short chain polyunsaturated fatty acids, notably linoleic and linolenic acids. The health of vegetarians and vegans appears to differ little from that of omnivores (Hardinge & Stare, 1954; Ellis & Montegriffo, 1970; Ellis, West & Sanders, 1977). Indeed, a vegan diet might be though to offer some advantage in relation to arteriosclerosis because animal tat has been implicated in its aetiology (Royal College of Physicians, 1976). In support of this suggestion, epidemiological evidence shows that the incidence of ischaemic heart disease is lower in countries where the typical diet contains a low proportion of animal products. However, in experimental animals changes in the fatty acid composition of the diet result in changes in the fatty acids of cell membranes which are associated with changes in the behaviour and function of the membranes (Holman, 1970a,b). In man information about these effects is not easily obtained and seemea to be important in view of the fact that the diet of large numbers of people in the Third World is predominantly of plant origin. Vegans seemed to offer an excellent natural ‘experimental model’ for the study of these effects. We decided also to study individuals on a vegetarian diet which is intermediate between that of vegans and omnivores and also because in this country vegetarians are much more common than vegans and the number of people adopting this diet seems to be increasing.     

“Antioxidant activity and characterization of protein fractions and hydrolysates from normal and quality protein maize kernels”

Maize is the main crop cultivated worldwide with more than 1 billion metric tons produced annually and is one of the most relevant sources of protein for human consumption in developing countries. Proteins and peptides isolated from maize exert relevant antioxidant activity which is increased by enzymatic hydrolysis. However, there is limited information about the antioxidant potential of proteins isolated from Quality Protein Maize (QPM) varieties and their hydrolysates. The aim of this research was to determine the differences in protein profile and antioxidant activity of protein fractions and hydrolysates between a hybrid white maize (Asgrow 773) and a QPM variety (CML-502). The biophysical evaluation and the total protein quantification by Kjeldahl and fractions by ninhydrin were consistent with the changes due to the breeding process of the QPM material. The antioxidant potential of the hydrolysates obtained from albumins and globulins had a 3-fold increase in both maize varieties. The prolamins hydrolysates presented an increase of 7-fold for the normal variety and 2-fold for the QPM variety. The results of this research allow indicate that the QPM varieties are a source of antioxidant peptides and promising candidates in the search for proteins and peptides with other bioactivities.     

玉米异位双胚与同位双胚籽粒的来源及其无融合生殖性

本文报道了在玉米自交系A上发现的异位双胚粒和同位胚粒的来源与无融合生殖性．结果指出:1．异位双胚粒是一个异位单胚粒和一个正常单胚粒或者两个异位单胚粒在籽粒形成过程中合二为一形成的子房融合籽粒；2．同位双胚粒是合子胚在胚胎发育过程中一分为二裂生形成的孪生双胚籽粒；3．以紫胚玉米的紫胚等当代直感性状为标记性状测定了异位双胚粒与同位双胚粒的无融合生殖性，结果显示，异位双胚粒和同位双胚粒均不是无融合生殖体．     

Tetrodotoxin--distribution and accumulation in aquatic organisms, and cases of human intoxication

Many pufferfish of the family Tetraodontidae possess a potent neurotoxin, tetrodotoxin (TTX). In marine pufferfish species, toxicity is generally high in the liver and ovary, whereas in brackish water and freshwater species, toxicity is higher in the skin. In 1964, the toxin of the California newt was identified as TTX as well, and since then TTX has been detected in a variety of other organisms. TTX is produced primarily by marine bacteria, and pufferfish accumulate TTX via the food chain that begins with these bacteria. Consequently, pufferfish become non-toxic when they are fed TTX-free diets in an environment in which the invasion of TTX-bearing organisms is completely shut off. Although some researchers claim that the TTX of amphibians is endogenous, we believe that it also has an exogenous origin, i.e., from organisms consumed as food. TTX-bearing animals are equipped with a high tolerance to TTX, and thus retain or accumulate TTX possibly as a biologic defense substance. There have been many cases of human intoxication due to the ingestion of TTX-bearing pufferfish, mainly in Japan, China, and Taiwan, and several victims have died. Several cases of TTX intoxication due to the ingestion of small gastropods, including some lethal cases, were recently reported in China and Taiwan, revealing a serious public health issue.     

Cloning and Functional Analysis of Calcineurin Subunits A and B in Development and Fecundity of Nilaparvata lugens (St(a)l)

Serine/threonine phosphatase calcineurin (CN) is a unique but confounding calcium/calmodulin-mediated enzyme,which is composed of a catalytic subunit A (CNA) an...     

正交式香蕉茎叶疏解粉碎机设计与试验

针对香蕉茎叶粗大、纤维长韧、含水率高等问题，研究设计一款专用于香蕉茎叶粉碎还田机。样机在普通粉碎机只能进行单向切割以粉碎的基础上，首次增加了两级纵向疏解齿辊和拾取耙轮，以实现香蕉茎叶正交式粉碎还田的机械化。以本机具进行田间试验。结果表明：该样机生产率为10.4 t/h；工作效率达到0.38 hm2/h；香蕉茎叶的切碎率为87.8 %，符合香蕉茎叶粉碎还田的农艺要求。该机有利于改善土壤养分，提高香蕉茎叶的综合利用率，具有极高的使用推广价值和意义。     

Potato freezing injury and survival,and their relationships to other stress

Breeding and selection for frost resistant potatoes with high yield and good quality is very promising. This has been demonstrated in a frost resistance breeding program conducted at the International Potato Center, Lima, Peru. Yield trials were conducted using selected frost resistant clones at various Andean locations at elevations from 3,200 to 3,900 meters (14). During the growth season, several hail storms and frosts occurred at these locations. These freezes (?3°C to ?4°C) were very useful in elimination of the undesirable clones under natural conditions. Clones with yield from 1 to 2 kg/plant have been selected. A yield of 1 to 2 kg/plant was superior to most common cultivars grown in the Andes. The difference in frost resistance between a resistant and sensitive type of potato is about 3 to 4°C.Solanum tuberosum is a sensitive type which, in most cases, can survive at about ?2.0°C. Evidence indicates that the difference in resistance to freezing injury is due to the genotype’s capability to tolerate freeze-induced dehydration and to withstand the aggregation of proteins under freezing stress. It is likely that freezing injury is caused primarily by the loss of membrane integrity and, therefore, that membrane thermal stability is paramount in the tolerance to freezing stress.     

Improve Anthocyanin and Zinc Concentration in Purple Rice by Nitrogen and Zinc Fertilizer Application

Zinc (Zn) is an essential micronutrient for plant growth and development, and anthocyanin is a secondary metabolite compound generally produced under stress conditions; both have benefits to human health. Rice is a staple food crop for most of the world’s population, and purple rice is well known as a natural source of Zn and anthocyanins, but their stability depends upon many factors. This review focuses on the opportunity to increase Zn and anthocyanin compounds in purple rice grains via Zn and nitrogen (N) management during cultivation. Variation in grain Zn concentration and anthocyanin compounds is found among purple rice varieties, thus presenting a challenge for breeding programs aiming at high grain Zn and anthocyanin contents. Genetic engineering has successfully achieved a high-efficiency vector system comprising two regulatory genes and six structural anthocyanin-related genes driven by endosperm-specific promoters to engineer purple endosperm rice that can provide new high-anthocyanin varieties. Grain Zn and anthocyanin concentrations in rice can also be affected by environmental factors during cultivation, e.g., light, temperature, soil salinity and nutrient (fertilizer) management. Applying N and Zn fertilizer is found to influence the physiological mechanisms of Zn absorption, uptake, transport and remobilization to promote grain Zn accumulation in rice, while N application can improve anthocyanin synthesis by promoting its biosynthesis pathway via the use of phenylalanine as a precursor. In summary, there is an opportunity to improve both grain Zn and anthocyanin in purple rice by appropriate management of Zn and N fertilizers during cultivation for specific varieties.     

Disease and pest resistance in grains of sorghum and millets

In this review available information on the mechanisms of resistance to insect pests and fungal pathogens in sorghum and millets is discussed. The primary source of resistance lies in the chemical and physical make up of the grain. Phenolic compounds such as ferulic acid and tannins present in some sorghums are potent inhibitors of pests and pathogens. Grain hardness is a major deterrent to infection and infestation in low tannin grains. The prolamins, the grain storage proteins of sorghum, are organized into protein bodies and provide a physical and a nutritional barrier since they are resistant to digestion by insect and fungal proteases. A plethora of proteins that belong to the ‘pathogenesis related protein’ group are distributed in various parts of the grain. Some of them are located in protein bodies. Notwithstanding, sorghum is still susceptible to insect pests and fungal pathogens. An understanding of the natural mechanisms of resistance in the grain is paramount for the development of durable resistance against pests and pathogens. The pyramiding of resistance genes and the development of transgenic lines based on this understanding are two sources of hope for the future protection of sorghum and millets.     

杂交水稻抗病虫育种实践与思考

我国是水稻生产大国,也是消费大国。新中国成立70多年来,我国的水稻事业取得了显著发展,特别是杂交水稻的发明为我国的粮食安全提供了坚强保障。在当前粮食生产减少农药、化肥施用的"双减"目标新形式下,培育高产、优质、抗逆和广适应性的水稻新品种势在必行。笔者就高抗稻瘟病恢复系明恢63及几个抗飞虱恢复系的育种实践向大家做介绍。     

不同水源及培养瓶对马铃薯试管苗和试管薯的影响

试管薯体积小,不耐储藏是试管薯应用的瓶颈。培育健壮脱毒马铃薯试管苗是生产高质量试管薯的前提。以脱毒马铃薯试管苗克新13和荷兰15为材料,通过对不同水源(自来水和蒸馏水)和培养瓶(透气和不透气)生产的试管苗和试管薯的比较,得出以下结论:自来水比蒸馏水生产的试管苗健壮,试管薯体积比较大;透气瓶生产的试管薯外观好,无气孔外翻现象,耐储藏。     

热研4号王草袋泡茶的加工制作及活性成分分析

热研4号王草是象草和美洲狼尾草的杂交种.热研4号王草是一种植株高大、产量高、嫩茎多汁而略具甜味,叶柔嫩,动物适口性好的热带禾本科牧草.本研究通过低温干燥王草,粉碎形成草粉,分装制成王草袋泡茶;王草袋泡茶浸泡后,茶汁呈橙黄色,略带甜味,具新鲜牧草芳香味,是一种独具特色的禾本科牧草茶饮料.对袋泡茶的活性成分的分析结果表明,王草中总黄酮含量为28.90 mg/g;多酚含量为12.63 mg/g;维生素C含量为41.39(mg/100g),这表明王草中含有丰富的对人体具有保健作用的活性成分.同时,王草袋泡茶加工制作的成功对开发其他热带禾科牧草具有重要的借鉴意义.     

TerraRossa: A Mid-Season Specialty Potato with Red Flesh and Skin and Resistance to Common Scab and Golden Cyst Nematode

TerraRossa (POR01PG20–12) is a mid-season specialty potato, released by Oregon State University, and is a product of the Northwest Potato Variety (Tri-State) Development Program. This cultivar is unique among commercially available potato cultivars in that plants produce small- to medium-sized smooth, oblong- to long-shaped tubers with red skin and red flesh. Total tuber yields of TerraRossa are similar to Dark Red Norland and less than Red La Soda. Average tuber size (136 g) is less than both of the comparison cultivars, reflecting inherent differences in tuber size distribution. TerraRossa tubers have total antioxidant levels higher than traditional white fresh varieties and comparable to the All Blue purple potato, known for its high antioxidant levels. Sensory evaluations of TerraRossa tubers indicated that it has good culinary attributes following boiling, baking, and microwaving. Potato chips made from TerraRossa tubers retained their unique red color, which represents a novelty in the chipping industry. TerraRossa could be a good candidate for the organic sector due to its tolerance to common scab (Streptomyces scabies) and tuber late blight (Phytophthora infestans) and its resistance to golden cyst nematode (Globodera rostochiensis). Due to its high yields, high chipping quality, good culinary properties, high antioxidant content and disease resistance, TerraRossa is a good candidate for opening new specialty type markets, adding diversity to the marketplace.     

Relation between the severity of Sigatoka disease and banana quality characterized by pomological traits and fruit green life

Banana fruit are typically harvested at a green preclimacteric stage prior to sale. The green life (GL), which is defined as the number of days between harvesting and initiation of the natural ripening process, is important for harvesting, shipping and marketing. Sigatoka disease (SD) has previously been shown to influence the postharvest quality of banana fruit. The present study was conducted to determine (1) whether there is a relationship between the level of SD severity and the banana quality as characterized by several pomological traits and fruit green life, and (2) whether there is a level of SD severity that is acceptable for fruit exporting. In an experiment conducted with fruit harvested at a constant physiological age, our results showed that the disease decreases fruit GL. Based on the relationship established between SD severity and GL, it is possible to define an acceptable disease level threshold corresponding to a specified GL. Additionally, we found that high SD infections caused a reduction in fruit weight but did not affect fruit size. Possible explanations are discussed.     

疫霉菌的研究现状及展望

在各种植物病害中,由疫霉菌引起的疫病是一类重要病害.主要阐述了疫霉菌的分类地位,一般形态特征,生活史,寄主范围,自身特性 (分离、培养和保存特性,交配特性,游动孢子的特性,致病力分化及遗传特性,生态特性,诱导特性,抗药特性),致病机制及检测技术,并指出了今后的研究方向 (各地区疫霉菌中主要致病种的重新确定,敏感基线的建立、抗药性发生动向的监测,病原菌致病基因的构建、调控及防治手段研究的新重点).     

Identification and Characterization of a Novel Lectin from the Clam Glycymeris yessoensis and Its Functional Characterization under Microbial Stimulation and Environmental Stress

Lectin from the bivalve Glycymeris yessoensis (GYL) was purified by affinity chromatography on porcine stomach mucin–Sepharose. GYL is a dimeric protein with a molecular mass of 36 kDa, as established by SDS-PAGE and MALDI-TOF analysis, consisting of 18 kDa subunits linked by a disulfide bridge. According to circular dichroism data, GYL is a β/α-protein with the predominance of β-structure. GYL preferentially agglutinates enzyme-treated rabbit erythrocytes and recognizes glycoproteins containing O-glycosidically linked glycans, such as porcine stomach mucin (PSM), fetuin, thyroglobulin, and ovalbumin. The amino acid sequences of five segments of GYL were acquired via mass spectrometry. The sequences have no homology with other known lectins. GYL is Ca²⁺-dependent and stable over a range above a pH of 8 and temperatures up to 20 °C for 30 min. GYL is a pattern recognition receptor, as it binds common pathogen-associated molecular patterns, such as peptidoglycan, LPS, β-1,3-glucan and mannan. GYL possesses a broad microbial-binding spectrum, including Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Vibrio proteolyticus), but not the fungus Candida albicans. Expression levels of GYL in the hemolymph were significantly upregulated after bacterial challenge by V. proteolyticus plus environmental stress (diesel fuel). Results indicate that GYL is probably a new member of the C-type lectin family, and may be involved in the immune response of G. yessoensis to bacterial attack.     

Ricin accumulation and degradation during castor seed development and late germination

The castor plant (Ricinus communis L.) is a euphorb, commonly grown for its high seed oil content. The seed also contains a deadly toxin known as ricin (RCA₆₀) and the less toxic Ricinus communis agglutinin (RCA₁₂₀) in addition to potentially harmful allergens. Using Western blotting, an antibody screening technique, ricin content was evaluated in various plant parts with a ricin A-chain specific antibody. Seed, cotyledon, root, hypocotyl, and leaf tissues were tested. Western blot results indicated that ricin is only present in the seed. In order to determine when ricin accumulates in the seed, reproductive tissue samples were harvested during seed development and upon germination. Developing seed were collected from inflorescences in 4-day intervals beginning with the day of pollination (day 0) until the seed had fully matured (day 44). Ricin was absent from the developing seed throughout development until the 28th day post-pollination. Ricin content quickly increased as the seed matured and the capsule dehydrated. Mature seed were also germinated and collected at 2-day intervals once radicle emergence began, until the 12th day, when seedlings were fully expanded. From the sixth day forward, germinating seedlings were dissected into root, hypocotyl, and cotyledonary tissue. Western blot analysis indicated that after the 6th day, ricin is degraded below levels of detection. Ricin is only detectable in the seed tissue from day 0 (ungerminated seed) through the sixth day after radicle emergence and is not detected in any of the root, hypocotyl, or cotyledonary tissue. These data suggest that ricin is generated and stored in the seed for a specific purpose; most likely the protection of the seed from predation in its quiescent state.