The acclimation of anemone fishes to sea anemones: Protection by changes in the fish''s mucous coat

The anemone fish Amphiprion clarkii (Bennett) lives unharmed among the tentacles of sea anemones following acclimation. What occurs during this process is unknown; however, two hypotheses have been formulated recently. One suggests that the fish coats itself with anemone mucus to mask its chemical stimulus for cnida discharge. The second suggests that the fish is protected by some alteration in its own mucous coating.

In order to test these alternative hypotheses, a surrogate anemone was constructed and an Amphiprion allowed to associate with it prior to being placed with a real anemone. If the subsequent acclimation times to a real anemone are reduced significantly after exposure to the surrogate anemone, one would conclude that the fish does not need to coat itself with anemone mucus to become protected.

After association with a surrogate anemone, it was found that the acclimation times of isolated A. clarkii to the sea anemone Macrodactyla doreensis (Quoy & Gaimard) decreased seven-fold. These results support the hypothesis that the fish is responsible for manufacturing its own protection from sea anemones, presumably by independently altering its own mucous coat during acclimation.     

Organ-specific distribution of dietary alkaloids in the marine opisthobranch Tylodina perversa

Specimens of the opisthobranch Tylodina perversa that were observed while feeding on the sponge Aplysina aerophoba were transferred to seawater tanks along with their prey and kept under controlled conditions. After one week the opisthobranchs were anaesthetized, dissected and studied for sequestered sponge-derived brominated alkaloids. All parts of T. perversa analyzed including feces, mucus and egg masses that had been produced during captivity contained alkaloids derived from A. aerophoba. The highest total alkaloid concentration (24.6 mg g⁻¹ dry wt) was found in mantles of T. perversa (compared to 51.2 mg g⁻¹ dry wt of total alkaloids in A. aerophoba). Hepatopancreas, egg masses and mucus (respective total alkaloid concentrations ranging from 20.4 to 12.5 mg g⁻¹ dry wt) were also rich in alkaloids. Whereas in A. aerophoba the isoxazoline alkaloids aerophobin-2 and isofistularin-3 were present in almost equal concentrations, aerophobin-2 constituted by far the major alkaloid (amounting to approximately 70% of all identified alkaloids) in mantles, mucus and egg masses of T. perversa, indicating selective sequestration by the opisthobranchs. Mantles as well as mucus also contained appreciable concentrations (approximately 20% of all identified compounds) of the brominated alkaloid aerothionin; this is not detected in A. aerophoba. It is possible that aerothionin originates from a previous encounter of T. perversa with the sponge A. cavernicola, the latter being closely related to A. aerophoba. The enrichment of aerophobin-2 (and of aerothionin) in mantles, mucus and egg masses that are vulnerable and exposed (mantles and egg masses) to predators and/or pathogens argues for defensive functions of the respective alkaloids even though this hypothesis still needs to be experimentally corroborated.     

The chemical nature of host hatching factors in the monogenean skin parasites Entobdella soleae and Acanthocotyle lobianchi

Fully-developed eggs of the monogenean Entobdella soleae from the skin of the common sole (Solea solea) hatch when treated with dilute solutions of urea or ammonium chloride in sea water. There is some evidence that arginine may stimulate hatching but the eggs do not respond when treated with sea water solutions containing trimethylamine oxide or glutamine. Sole skin mucus contains sufficient urea to stimulate hatching but insufficient ammonia. Solutions of urea in sea water stimulate hatching in the monogenean parasite Acanthocotyle lobianchi found on ray skin. Sea water solutions containing ammonium chloride and trimethylamine oxide failed to hatch the eggs of A. lobianchi and the eggs were also insensitive to various amino acids made up at concentrations found in host mucus. Experiments with urease confirmed that urea in ray ventral skin mucus is the host hatching factor for A. lobianchi. Skin mucus from the common sole failed to stimulate hatching in A. lobianchi. The role as hatching factors of excretory products in host gill effluent, skin mucus and urine is discussed.     

MUC16 is produced in tracheal surface epithelium and submucosal glands and is present in secretions from normal human airway and cultured bronchial epithelial cells

The gel-forming MUC5AC and MUC5B mucins have been identified as major components of human airway mucus but it is not known whether additional mucin species, possibly with other functions, are also present. MUC16 mucin is a well-known serum marker for ovarian cancer, but the molecule has also been found on the ocular surface and in cervical secretions suggesting that it may play a role on the normal mucosal surface. In this investigation, the LUM16-2 antiserum (raised against a sequence in the N-terminal repeat domain) recognized MUC16 in goblet and submucosal gland mucous cells as well as on the epithelial surface of human tracheal tissue suggesting that the mucin originates from secretory cells. MUC16 mucin was present in 'normal' respiratory tract mucus as well as in secretions from normal human bronchial epithelial (NHBE) cells. MUC16 from NHBE cells was a high-molecular-mass, monomeric mucin which gave rise to large glycopeptides after proteolysis. N- and C-terminal fragments of the molecule were separated on gel electrophoresis showing that the MUC16 apoprotein undergoes a cleavage between these domains, possibly in the SEA domain as demonstrated for other transmembrane mucins; MUC1 and MUC3. After metabolic labeling of NHBE cells, most of the secreted monomeric, high-molecular-mass [(35)S]sulphate-labelled molecules were immunoprecipitated with the OC125 antibody indicating that MUC16 is the major [(35)S]sulphate-labelled mucin in NHBE cell secretions.     

Isolation and characterization of glycoproteins from canine tracheal pouch secretions.

Canine tracheal pouch secretions were solubilized with 1% sodium dodecyl sulfate and visualized by sodium dodecyl sulfate-agarose-acrylamide gel electrophoresis. Intact mucus, and water-soluble and insoluble fractions of mucus were shown to be composed of high molecular weight glycoproteins (Mr greater than or equal to 3 . 10(6)) and three major classes of proteins of lower molecular weight (Mr approximately 4 . 10(5), 2 . 10(5), and 6 . 10(4)). When the mucus secretions were further treated with a reducing agent, the glycoproteins were dissociated into subunits which appeared on the gel as three discrete bands. Separation of the high molecular weight glycoproteins from the other proteins was achieved by gel filtration on Biogel A-15m in the presence of 1% dodecyl sulfate following reduction and alkylation of mucus. These glycoproteins were further resolved, using DEAE cellulose chromatography in the presence of 6 M urea, into two protein fractions. Both fractions contained approximately 87% carbohydrate, high amounts of serine and threonine but differed significantly in contents of N-acetyl glucosamine and sialic acid; their mobility on gel electrophoresis was also different. Significant contents of cysteine were noted in both fractions. Results of this study indicate that the canine tracheal pouch preparations provide normal tracheal secretions which bear similarity in structure to the tracheobronchial secretions obtained from human patients.     

Histamine and leukotriene concentrations in duodenal tissue and mucus of lambs selected for high and low responsiveness to vaccination and challenge with Trichostrongylus colubriformis

Lambs selectively bred for high responsiveness or low responsiveness to vaccination with irradiated Trichostrongylus colubriformis were vaccinated and challenged. Duodenal tissue histamine concentrations in both high and low responder lambs were lower at 3 days than at 28 days after challenge. At 3 days after challenge, histamine concentrations were higher in both male and female high responder lambs than in low responder lambs whereas at 28 days concentrations were increased only in high responder females. At 3 days after challenge, histamine concentrations were generally lower in mucus than in tissues, but levels were again higher in mucus from high responder groups. In duodenal tissue at 3 days after challenge, leukotriene C₄ and B₄ concentrations were similar in high and low responder animals. At the same time, concentrations of both leukotrienes were higher in mucus than in tissues, with high responder female lambs having the highest concentration. It is suggested that increased levels of histamine and leukotrienes in mucus and tissue are associated with larval rejection or exclusion.     

Aquaculture of sponges on scallops for natural products research and antifouling

Suspended culture of scallops (Pectinidae: Bivalvia) is plagued by invertebrate fouling. Scallops covered in an orange sponge (Suberites ficus ssp. rubrus), however, do not have any other invertebrates fouling their shells and the sponge is easily removed. Sponges may also be valuable sources of bioactive compounds. Seven species of sponge were found to be associated with Chlamys opercularis but none were found associated with Pecten maximus. Standing crop of sponge on the scallop farm was just over one tonne. If all the scallops were covered by sponge this would rise to approximately 4.5 tonnes (from three million scallops). Primary cell cultures of (S.f. rubrus) were successfully established but no cell lines were achieved. A number of techniques were tried for establishing cells and pieces of sponge tissue onto scallop shells but none gave satisfactory results. Likewise mechanical methods for sticking small pieces of sponge to scallop shells were deemed impractical even where they resulted in subsequent sponge growth. Improving natural settlement of sponges onto the scallops was the only economically practical method for increasing sponge yield for C. opercularis, though other methods would need to be devised for P. maximus.     

pH homeostasis of the circadian sporulation rhythm in clock mutants of Neurospora crassa

The influence of environmental (extracellular) pH on the sporulation rhythm in Neurospora crassa was investigated for wild-type (frq⁺) and the mutants chr, frq¹, frq⁷, and frq⁸. In all mutants, including wild type, the growth rate was found to be influenced strongly by extracellular pH in the range 4-9. On the other hand, for the same pH range, the period length of the sporulation rhythm is little influenced in wild type, chr, and frq¹. A loss of pH homeostasis of the period, however, was observed in the mutants frq⁷ and frq⁸, which also are known to have lost temperature compensation. Concerning the influence of extracellular pH on growth rates, a clear correspondence between growth rates and the concentration of available H₂PO₄^- ion has been found, indicating that the uptake of H₂PO₄^- may be a limiting factor for growth under our experimental conditions. The loss of pH compensation in the frq⁷ and frq⁸ mutants may be related to less easily degradable FRQ^7,8 proteins when compared with wild-type FRQ. Results from recent model considerations and experimental results predict that, with increasing extra-and intracellular pH, the FRQ⁷ protein degradation increases and should lead to shorter period lengths. (Chronobiology International, 17(6), 733-750, 2000)     

束花石斛的繁育生物学特性

为了探究束花石斛（Dendrobium chrysanthum）的繁育生物学特性,对其开花习性、花粉活力、柱头分泌特性、人工授粉结实率、自然结实种子育性和贮藏特性进行研究,结果表明：（1）束花石斛花芽萌动期为19d,现蕾期为23 d,群体花期为28 d,单花寿命10～15 d;(2)开花1～3 d花粉活力保持在90%左右,开花至第9天时花粉活力仅为23.7%,初始3 d开花的花粉活力与其他时间取样的活力差异均达极显著水平（P<0.01）,花粉活力随开花时间延长呈由强到弱的趋势;（3）束花石斛的柱头腔从开花第2天开始有分泌物,第6 d时分泌物最多,柱头过氧化氢染色结果表明在开花5～6 d时柱头可授性最强,柱头可授性随开花时间延长呈由弱到强再到弱的趋势;（4）选取花朵开放4 d的花粉和柱头人工授粉,同株异花和同花授粉未见结实。野外结实果质量2.02～4.83 g,种子长0.628～0.845 mm,宽0.082～0.110 mm,长宽比为7.798,成胚率达97.35%,种子活力为90.80%,室温条件保存6个月的种子活力维持在73.20%。上述结果说明,束花石斛单花花期不长,开花初...     

小黑杨转录因子PsnbZIP1应答盐胁迫功能分析

为揭示小黑杨(Populus simonii×P. nigra)在面对非生物胁迫时,转录因子PsnbZIP1在植物体内发挥的功能,以小黑杨为试验材料,克隆得到PsnbZIP1的ORF区序列长为432 bp,并初步分析PsnbZIP1盐胁迫下的分子机制。采用q-PCR分析PsnbZIP1在150 mmol·L^-1 NaCl处理小黑杨组培苗时的表达模式,发现该基因的表达量快速上升;通过生物信息学分析预测PsnbZIP1转录因子为无跨膜结构且具有信号肽的亲水性不稳定蛋白;用农杆菌(Agrobacterium)介导的烟草(Nicotiana)瞬时表达观察该基因的亚细胞定位情况,结果表明该基因为核定位蛋白;用酵母单杂交实验证明该基因编码的蛋白在酵母体内不具有转录激活功能。对PsnbZIP1基因的启动子序列进行分析,结果表明该启动子包含了生长素应答、脱落酸应答元件、光应答元件以及种子特异性调控的顺式作用调控元件,该基因可能在植物的生长发育与响应胁迫过程中发挥了重要作用;启动子还包括参与干旱诱导的MYB结合位点和MYBHv1结合位点,表明该基因有可能与一些干旱诱导相关MYB基因...     

Integumentary structure and its relationship to wiping behaviour in the common Indian tree frog, Polypedates maculatus

Skin of the Indian tree frog, Polypedates maculatus (Rhacophoridae), was studied in the context of self-wiping behaviour which functions to expel and distribute cutaneous secretions recently shown to retard evaporative water loss. The secretions contain both mucus and lipids and are derived from a common gland considered to be homologous with characteristic anuran mucous glands. The glands are bipotent and secrete both mucus and lipoid products which are evidently mixed within the glandular lumen. Another type of gland resembling characteristic anuran serous (or granular) glands is found in dorsal but not ventral skin, whereas the lipid-secreting mucous glands are found in skin associated with all body surfaces. There is no distinct, lipid-secreting gland present in the skin of this species other than the mucous glands. These histochemical data complement the earlier finding that resistance to evaporative water loss in this species is relatively small compared with phyllomedusine 'waterproof frogs which also exhibit wiping behaviour associated with secretion of lipids. Thus, wiping behaviour may have evolved in association with mucous secretions before dominant lipoid secretions resulted from strong selection for water conservation.     

银耳菌糠黑色素的理化性质及抗氧化和抑菌活性

银耳菌糠中存在一种银耳的伴生菌——炭团菌(俗称香灰菌),其菌丝生长到一定阶段后会产生大量的黑色素,具有广泛的应用价值。本研究从银耳菌糠中提取黑色素,研究其理化性质、抗氧化活性及抑菌作用。通过紫外-可见光谱、傅里叶红外光谱对提取的黑色素进行鉴定,表明银耳菌糠黑色素具有黑色素的典型特征。通过对银耳菌糠黑色素理化性质的研究,表明银耳菌糠黑色素是一种趋于黑色并略带红色和黄色的粉末;该黑色素易溶于碱性溶液;具有较好的热稳定性和光稳定性,其稳定性受氧化剂和还原剂的影响较小,受Ca²⁺、Cu²⁺的影响较明显。通过总抗氧化能力(FRAP法)、自由基清除能力检测银耳菌糠黑色素的抗氧化活性,研究表明黑色素具有较高的抗氧化活性,羟自由基、ABTS自由基清除的EC₅₀值分别为0.429 mg/mL和0.016 mg/mL。本研究还检测了黑色素对革兰氏阳性、革兰氏阴性细菌的抑菌能力,结果表明该黑色素在浓度为3.2 mg/mL时对供试菌株的抑菌率超过90%,且对革兰氏阳性菌会较敏感。本研究为银耳菌糠的有效利用及其黑色素产品的开发提供了理论基础,具有较高的经济价值。     

不同降水条件下内蒙古荒漠草原主要植物物候对长期增温和氮添加的响应

植物物候是生态系统对气候变化响应的重要指示器,是植物生产力与植被动态模拟的重要参数。但是植物物候对全球变化的响应是否存在年际间变异、年内变异、物种间变异或生境间变异,以及如何改变,目前仍然不明确。该研究基于内蒙古荒漠草原长期增温和氮添加实验平台,选择优势植物短花针茅(Stipa breviflora)、冷蒿(Artemisia frigida)和木地肤(Kochia prostrata)为研究对象,使用物候打分观测方法和Richards生长曲线拟合方法,研究了实验处理第11、12和13年(2016–2018年)期间增温和氮添加对植物物候的影响。研究结果表明:(1)短花针茅开花时间集中在第129–145天,冷蒿开花时间集中在第230–248天,木地肤开花时间集中在第194–222天。增温、氮添加和增温+氮添加均使短花针茅和木地肤开花时间趋于提前,冷蒿开花时间趋于推迟。(2)短花针茅结果时间集中在第134–148天,冷蒿结果时间集中在第241–260天,木地肤结果时间集中在第207–231天。增温、氮添加和增温+氮添加处理均使短花针茅和木地肤结果时间趋于提前,冷蒿结果时间趋于推迟。(3)短...     

橡胶草TkAPC10基因的鉴定及其表达模式分析

APC/C是一类泛素连接酶E3复合体,在调控细胞周期过程中发挥重要作用。为了揭示橡胶草APC/C蛋白复合体的功能,鉴定了橡胶草TkAPC10基因,并对其表达模式进行了分析,初步确定了其功能。TkAPC10基因的ORF为579 bp,编码192个氨基酸,其基因组DNA序列为1 092 bp,包含6个外显子和5个内含子。基因组分析发现,TkAPC10以单拷贝的形式存在,其启动子序列除了含有TATA-box和CAAT-box增强子元件外,还有ABA、JA、光以及逆境响应相关的顺式作用元件。系统进化关系分析发现,不同物种的APC10蛋白具有很高的同源性,TKAPC10与莴苣LsAPC10的相似性最高达到99%,而与其他菊科植物的APC10蛋白相似性也达到95%以上。进一步采用qRT-PCR技术对TKAPC10的表达模式进行分析,结果表明,该基因在细胞分裂旺盛的组织（花、叶和根）中的表达量显著高于细胞分裂活动相对缓慢的组织（花梗）。外源ABA处理后,TKAPC10基因转录水平显著下降;而MeJA和ET处理后,该基因显著上调表达。经PEG6000以及甘露醇处理后,TKAPC10表达水平显著下降;而...     

光系统II实际光化学量子效率对光的响应模型的比较

为了比较光系统II实际光化学量子效率(Φ_PSII)对光的响应机理模型(简称机理模型)、负指数模型和指数模型的优缺点, 用LI-6400-40B光合作用测定仪控制CO₂浓度和温度, 测量了剑叶金鸡菊(Coreopsis lanceolata)、黄荆(Vitex negundo)和大狼杷草(Bidens frondosa)的电子传递速率(ETR)对光的响应曲线(ETR-I)和Φ_PSII对光的响应曲线(Φ_PSII-I), 然后用这3个模型分别拟合了这些数据。拟合结果表明: 3个模型都可以较好地拟合这3种植物的ETR-I的响应数据和Φ_PSII-I的响应数据, 但由指数模型拟合ETR-I和Φ_PSII-I的响应数据得到相应的饱和光强(PAR_sat)和光系统II最大光能利用效率(F_v/F_m)之间存在显著差异, 且估算的饱和光强远低于实测值。由机理模型可知, Φ_PSII不仅与光强的函数有关, 还与植物的内禀特性有关, 即与天线色素分子的本征光能吸收截面、激子的传递效率、能级的简并度、光化学反应常数、热耗散常数和处于最低激发态的平均寿命等参数有关。此外, 由机理模型还可知, Φ_PSII随光强的增加而下降的原因是捕光色素分子的有效光能吸收截面随光强增加而降低。     

~(32)P示踪法研究溶磷真菌对磷肥转化固定和有效性的影响

采用³²P示踪技术,研究了溶磷青霉菌P8对肥料磷与土壤有效磷的转化、固定和有效性的影响.结果表明,溶磷青霉菌菌剂能够增加玉米、花生的生物量,促进作物对土壤和肥料磷素的吸收;溶磷菌剂具有防止有效磷转化为难溶Ca₁₀-P的作用,增加有效态磷(Ca₂-³²P、Ca₈-³²P)的比例.随时间延长,施入的³²P转化为Ca₁₀-P的数量(或比例)逐渐增加,但是相对于未接种菌剂处理,接种青霉菌菌剂的土壤磷和肥料磷转化为Ca₁₀-P比例最低.溶磷青霉菌菌剂不仅能够防止有效磷向难溶磷Ca₁₀-P的转化,而且其效果能够维持较长时间.     

多鳞四须鲃耗氧率、排氨率和窒息点的初步研究

控制水温在(20±0.5)℃条件下,采用Winkler法和奈氏试剂法分别测定水中的溶氧含量和氨氮含量,通过比较流水呼吸室进、出口水中的溶解氧和氨氮含量之差以确定多鳞四须鲃(Barbodes schwanenfeldi)的耗氧率、排氨率及窒息点.结果表明,多鳞四须鲃耗氧率随体重增加而减小,关系式为Y=0.24X^-0.09(R²=0.9028);随放养密度的增大而减小,关系式为Y=-0.029X+0.3301 (R²=0.9291).排氨率随体重的增加而减小,关系式为Y=-0.0008X+0.2433 (R²=0.9817);随放养密度的增大而增加,关系式为Y=-0.050X+0.4979 (R²=0.9889).多鳞四须隹巴晚间(18:00～4:00)的耗氧率明显高于白天(6:00-1:00),排氨率则相反,白天的排氨率相对较高,表明多鳞四须鲃巴属于"昼伏夜出"型鱼类.多鳞四须啬巴的窒息点为1.2572mg·L^-1,耐氧性较差.     

Two rheologically different gastric mucus secretions with different putative functions

Previous work has shown the presence of different mucin gene products and glycosylated species in gastric mucus secretions, however, the functional relevance of these differences is unclear. This study aimed to investigate rheologically, differences in the gel behaviour within gastric mucus samples using a pig model. Rheological measurements were made on a Bohlin CVO50 rheometer. Mucins were characterised by antigenicity, lectin reactivity and proteolytic fragmentation patterns. Two distinct mucus gel secretions, one compliant with and the other resistant to shear stress, were removed from the gastric mucosa. The two gels had different rheological behaviour profiles and exhibited structural differences in their constituent mucins. The shear-compliant mucus was located superficially to the adherent shear-resistant mucus layer and was shown not to be a proteolytic product of the latter. This study has demonstrated that there are two rheologically distinct mucus gel secretions with structural/compositional differences in the stomach. Rheological properties suggest that the adherent, shear-resistant gel could provide the mucus barrier in vivo while the shear-compliant gel could act primarily as a lubricant.     

Evaluation of Active Oxygen Effect on Photosynthesis of Chlorella vulgaris

The relationship between O₂ and an active oxygen scavenging system in Chlorella vulgaris var.vulgaris (IAM C-534) was investigated. When Chlorella vulgaris was exposed to 2% O₂, only traces of active oxygen scavenging enzymes were found. When the Chlorella vulgaris was treated with 20% or 50% O₂, it was shown that the level of enzyme activity increased as the O₂ concentration increased. An increase in enzyme activity was not found in any specific enzyme but in all of the enzymes, but the level of glutathione and ascorbate remained the same in all the cases. In addition, the photosynthetic efficiency also decreased as the concentration of O₂ was increased. These results suggest that an O₂ enriched environment can lead to an increase in the production of active oxygen species such as O_bullet2 and H₂O₂ and to a decrease in the photosynthetic efficiency in Chlorella vulgaris. The hydroxyl radical (^bulletOH) was detected directly in the Chlorella vulgaris suspension with a spin trapping reagent. It was also clear that the increase in the ^bulletOH intensity as the visible light intensity increased was unrelated to the O₂ concentration. It was suggested that the conditions for producing ^bulletOH and the other active oxygen species were different, and that two types of oxygen stress should exist in the Chlorella vulgaris.