猪链球菌和猪多杀性巴氏杆菌多重实时荧光PCR方法的建立

【背景】猪链球菌(Streptococcus suis,SS)和猪多杀性巴氏杆菌(Pasteurella multocida,Pm)都是能引起宿主致病的人畜共患病原菌,常出现混合感染,临床诊断上易与猪瘟、猪丹毒等混淆。【目的】快速、有效鉴别猪链球菌病和猪多杀性巴氏杆菌病,建立一种能同时检测2种病原的多重实时荧光定量PCR检测方法。【方法】基于猪链球菌的gdh基因和猪多杀性巴氏杆菌的plpE基因,设计2对特异引物及TaqMan探针,以细菌16S rRNA基因设计通用引物及探针,通过对反应条件优化,建立了一种能同时检测猪链球菌和猪多杀性巴氏杆菌的多重实时荧光定量PCR检测方法。【结果】该方法能够特异性地检测猪链球菌和猪多杀性巴氏杆菌,与细菌分离后的测序结果验证完全一致。此方法对重组质粒标准品的最低检出浓度分别为4.53×10²copies/μL和3.97×10²copies/μL。重复性试验结果显示,该方法的组内和组间变异系数均小于3%。【结论】本实验所建立的方法准确、简便、可靠,能够用于2种病原菌的同时检测,为猪链球菌病和猪多杀性巴氏杆菌病的防治提供了有效的检测工具,具有重要的流行病学意义和临床应用价值。     

2017–2019年中国南方五省规模化养猪场副猪格拉菌血清型、耐药性及β-内酰胺类耐药基因bla-TEM分子特征分析

【目的】旨在分析当前规模化养殖场副猪格拉菌(Glaesserella parasuis)优势血清型、耐药特性、耐药基因与分子特征。【方法】对源自规模化养猪场21株副猪格拉菌临床分离株,采用PCR鉴定血清型;利用K-B纸片扩散法鉴定其对25种抗生素的耐药表型;采用PCR检测bla-_TEM、bla-_NDM和bla-_CTX等7种耐药基因,并采用Chi-square test和Fisher exact test分析耐药表型和耐药基因型的相关性;耐药基因目的条带测序,并应用CLC Sequence Viewer软件分析β-内酰胺类耐药基因(bla-_TEM)编码蛋白氨基酸关键位点差异与耐药性的关系。【结果】21株副猪格拉菌临床分离株的优势血清型为4和12型;对β-内酰胺类药物苯唑西林的耐药性较强,耐药菌占比达61.9%(13/21);多重耐药菌株占比高达90.5%(19/21);β-内酰胺类耐药基因bla-_TEM携带率较高(52.4%,11/21),且bla-_TEM与β-内酰胺类药物青霉素G、苯唑西林和头孢拉定的耐药性显著相关,部分bla-_TEM编码氨基酸存在可能与副猪格拉菌耐药能力有关的差异位点。【结论】本研究表明,规模化养猪场的副猪格拉菌多重耐药情况仍很严重,并明确了被调查区域β-内酰胺类药物耐药率高的主要原因是携带耐药基因bla-_TEM,为加强对规模化养猪场副猪格拉菌耐药性监测提供理论依据。     

基于双重芯片式数字PCR快速鉴定KPC型碳青霉烯耐药肺炎克雷伯菌的方法

【背景】由于碳青霉烯类药物的泛用和滥用,致使肺炎克雷伯菌碳青霉烯耐药株与日俱增,产碳青霉烯酶是肺炎克雷伯菌对碳青霉烯类药物耐药的主要原因。目前对肺炎克雷伯菌碳青霉烯耐药株的检测方法存在费时费力、特异性差、灵敏度低等问题。【目的】建立一种能同时检测肺炎克雷伯菌和碳青霉烯酶基因bla_KPC的双重芯片式数字PCR方法。【方法】依据肺炎克雷伯菌的特有基因yhaI和碳青霉烯耐药基因bla_KPC保守序列设计特异性引物和探针,确定双重芯片式数字PCR同时对yhaI和bla_KPC两个基因核酸浓度绝对定量的检测范围、检出限和最佳实验体系,并进行方法特异性、灵敏度、重复性分析及临床菌株的检测。【结果】双重芯片式数字PCR检测灵敏度比双重实时荧光定量PCR提高了约1.5个数量级,在两基因同时检出的情况下,最低检出限分别为3.74 copies/μL (yhaI基因)和1.93 copies/μL (bla_KPC基因);优化后的双重芯片式数字PCR对参考菌株检测特异性的结果与双重实时荧光定量PCR结果一致;利用优化后的双重芯片式数字PCR方法共检测58株临床菌株,其中肺炎克雷伯菌43株,属肺炎克雷伯菌且含有bla_KPC基因的菌株13株,这与质谱及耐药谱检测结果一致。【结论】利用双重芯片式数字PCR技术建立了产KPC型碳青霉烯酶肺炎克雷伯菌的绝对定量检测方法。该方法特异性强、灵敏度高、准确度好,可用于检测具有碳青霉烯酶基因bla_KPC的肺炎克雷伯菌的核酸检测和定量分析,也为产其他类型碳青霉烯酶的病原菌检测提供了新的技术参考。     

云南地区鸭源沙门菌的分离鉴定及耐药性和毒力基因分析

【背景】沙门菌是一种重要的食源性人兽共患病原菌,可引起多种食源性疾病。【目的】了解云南地区鸭源沙门菌病的流行现状、耐药现象及毒力基因携带等基本情况。【方法】无菌采集云南各地区病死鸭肝脏样品169份进行沙门菌分离,对分离株进行血清分型鉴定、药敏及相关耐药基因、毒力基因筛查。【结果】分离到鸭源沙门菌48株,分离率为28.40%,鉴定出3种血清型,其中肠炎沙门菌为优势血清型。分离株对青霉素G、林可霉素、克林霉素和利福平的耐药率达100%,每株菌至少对3类6种及以上的抗生素耐药,单株最高可耐14种,产生了22种耐药谱型。共检出耐药基因5种,bla_TEM和tetB检出率分别为27.08%和22.92%,tetA、sul2和EBC的检出率较低。毒力基因共检出10种,其中,SPI-1(avrA)、SPI-3(mgtC)、SPI-4(siiD)、SPI-5(sopB)和bcfC检出率均高达100%,SPI-2(ssaQ)、spvB、spvC、pefA和stn的检出率均达60%以上,cdtB未检出。【结论】云南地区鸭源沙门菌主要流行血清型为肠炎沙门菌,耐药性及多重耐药情况严重,耐药机制复杂,耐药基因与耐药表型符合率低,毒力基因检出率较高。研究结果可为云南地区鸭群沙门菌病的防控和净化提供参考。     

一株兔源A型多杀性巴氏杆菌的分离鉴定和全基因组测序及分析

【背景】多杀性巴氏杆菌可导致猪肺疫、牛出血性败血症和兔出血性败血症等多种疾病,严重威胁多种动物畜牧养殖业的健康发展。【目的】重庆某兔场送检一批病死兔,为研究其病原和治疗方法,对病原进行了微生物分离和全基因组测序分析。【方法】从2022年重庆某兔场送检兔病料中进行细菌分离纯化、生化试验、16S rRNA基因鉴定、荚膜血清型分型、药敏试验和毒力基因检测,同时通过全基因组测序结果进行毒力、耐药基因注释和遗传进化等分子生物学信息分析。【结果】该菌为兔源A:ST74多杀性巴氏杆菌,命名为LXSS001,基因组序列上传到NCBI数据库(登录号为CP119523.1),药敏试验显示该菌对四环素、杆菌肽、复方新诺明和磺胺异恶唑耐药,对头孢噻肟、头孢哌酮和丁胺卡那等药物敏感。全基因组长度为2 480 671 bp,并注释到了58个毒力基因和9类药物的靶向抗药基因。通过联合建树表明其与3480株一致性最高。【结论】本研究完成了一株A型多杀性巴氏杆菌的分离鉴定和全基因组测序,并揭示了其与国内外其他分离株的进化关系,为多杀性巴氏杆菌的后续研究提供了参考依据。     

口蹄疫病毒O型中和抗体检测固相阻断ELISA方法的建立

【目的】为评价O型口蹄疫病毒(foot-and-mouth disease virus,FMDV)灭活疫苗免疫后中和抗体(neutralizing antibodies,NA)水平,建立检测中和抗体的固相阻断ELISA (neutralizing antibodies solid-phase blocking ELISA,NA-SPBE)方法。【方法】本研究以本实验室前期制备的FMDV广谱反应性牛源单克隆抗体E32作为捕获抗体,以生物素标记的FMDV O型型内广谱中和牛源单克隆抗体C4作为检测抗体,经过条件优化建立了检测FMDV O型中和抗体的固相阻断ELISA方法,并对该方法进行了敏感性、特异性、重复性、交叉反应性与病毒中和试验(virus neutralization test,VNT)相关性等试验。【结果】抗体E32最佳包被浓度为0.5 μg/mL,O型FMDV灭活抗原最佳稀释浓度为0.25μg/mL,生物素标记抗体C4-Bio最佳工作浓度为0.06 μg/mL,链霉亲和素-HRP的最佳稀释度为1:40 000。以1.35 log₁₀作为效价判定临界值时,敏感性和特异性分别为97.14%和98.84%。利用该方法分别检测FMDV A型、FMDV Asia1型、BVDV、PRRSV、CSFV、PPRV抗体阳性血清时,均为阴性,未出现交叉反应。该方法批内和批间重复试验的变异系数均<10%,表明其重复性较好。利用该方法与VNT分别对160份血清样品进行检测,二者的相关系数r为0.807 5,P<0.000 1,相关性显著。【结论】该方法可以检测FMDV O型中和抗体,为FMDV O型灭活疫苗免疫效果评价提供有力技术支撑。     

口蹄疫病毒结构蛋白VP1在谷氨酸棒状杆菌中的表达及优化

【背景】口蹄疫(foot-and-mouth disease, FMD)是由口蹄疫病毒(foot-and-mouth disease virus, FMDV)引起的感染牛、羊和猪等偶蹄动物的主要疫病之一。口蹄疫病毒的结构蛋白VP1包含多个能够引起机体免疫反应的主要位点,因此VP1是研究亚单位疫苗的方向靶标。谷氨酸棒状杆菌 (Corynebacterium glutamicum)作为安全生产菌株,是医药用蛋白生产的优势细胞工厂。【目的】利用C. glutamicum作为受体菌株表达外源蛋白的优势实现VP1的外源表达。【方法】根据VP1结构蛋白的基因序列、相应功能和C. glutamicum的密码子偏好性设计并合成VP1基因,与pXMJ19载体连接构成重组质粒pXMJ19-VP1。C. glutamicum CGMCC 1.15647菌株用于表达VP1-6×his蛋白,并对蛋白表达元件启动子、5′非翻译端(5′UTR)、目的蛋白自身N端等进行优化,同时对培养条件等进一步优化,采用SDS-PAGE和Western blotting技术检测VP1蛋白的表达情况。最后应用间接酶联免疫吸附试验(enzyme-linked immunosorbent assay, ELISA)测定本研究中生产的VP1的免疫活性。【结果】SDS-PAGE和Western blotting分析结果表明VP1蛋白能在C. glutamicum CGMCC 1.15647菌株成功表达,将P_tac启动子替换为合成型启动子P_H36能提高蛋白产量。在此基础上,通过插入不同的5′UTR序列和VP1蛋白N端氨基酸的改变能进一步提高蛋白产量并可利用CspB信号肽实现分泌表达。发酵试验表明,VP1摇瓶发酵培养最优条件为30 ℃、24 h。ELISA试验表明,本研究中的VP1可与阳性血清特异性结合。【结论】本研究在谷氨酸棒状杆菌中成功表达FMDV的VP1蛋白,并通过优化蛋白表达元件的方法进一步提高了产量,为开发新型FMD免疫诊断试剂和安全高效的亚单位疫苗奠定了良好的基础。     

焦化废水O/H/O生物处理工艺二级好氧生物反应器的微生物结构和功能

【背景】焦化废水O/H/O生物处理工艺的二级好氧生物反应器O₂具有剩余污染物矿化和完全硝化功能,对废水的达标排放有重要作用。【目的】阐明O₂生物反应器的微生物结构和功能。【方法】利用16S rRNA基因测序,研究O₂生物反应器的微生物多样性和组成并进行功能预测,揭示其共现性特征和环境影响因子。【结果】O₂的优势菌门以变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、绿菌门(Chlorobi)为主。主要菌属中红游动菌属(Rhodoplanes)、溶杆菌属(Lysobacter)、硫杆菌属(Thiobacillus)等参与化学需氧量(chemical oxygen demand,COD)、酚类(phenols)和硫氰酸盐(thiocyanate,SCN^-)等剩余污染物的去除,亚硝化弧菌属(Nitrosovibrio)和硝化螺菌属(Nitrospira)分别作为氨氧化细菌(ammonia-oxidizing bacteria,AOB)和主要的亚硝酸盐氧化细菌(nitrite-oxidizing bacteria,NOB)。功能预测结果显示苯甲酸酯降解、氨基苯甲酸酯降解、氯烷烃和氯烯烃的降解、氟代苯甲酸酯降解和硝基甲苯降解是外源物质生物降解和代谢的前五大通路,广泛分布在主要菌属中,验证了微生物降解剩余污染物的作用。基因pmoA/B/C-amoA/B/C、hao和nxrA/B编码相关的酶,组成了完整的硝化途径。共现网络结果揭示溶杆菌属、Candidatus Solibacter和红游动菌属在O₂生态中的重要地位。通过冗余分析(redundancy analysis,RDA)表明COD和NH₃是影响O₂微生物群落的主要因素。【结论】红游动菌属和溶杆菌属是O₂中最核心的功能菌属,在污染物矿化和维持群落生态稳定上有重要作用。亚硝化弧菌属和硝化螺菌属是硝化作用的核心菌属。O₂中的代谢通路以剩余污染物矿化和完全硝化为主,微生物群落主要受COD和NH₃的影响。本研究阐明了O₂的微生物结构与功能,为焦化废水O/H/O生物处理工艺的改进提供了微生物学上的依据。     

鸭疫里默氏杆菌流行菌株的分离鉴定及生物学特性

【背景】鸭疫里默氏杆菌(Riemerella anatipestifer,RA)是引起雏鸭、鹅、火鸡等多种家禽、野禽发生传染性浆膜炎的病原,在全世界范围内广泛存在,危害养禽业发展,造成严重的经济损失。【目的】了解国内RA的流行现状,探究该菌的生物学特性,更好地指导防控鸭疫里默氏杆菌病。【方法】对2020-2021年从山东省、河北省、广东省、山西省等地分离的RA疑似菌株进行PCR、生化和血清型鉴定,并根据药物敏感性结果分析耐药现象,根据半数致死量(median lethal dose,LD₅₀)测定结果分析致病力差异。【结果】共鉴定78株RA分离株,其中,血清1型4株、2型21株、10型11株、6型3株、7型17株,1株有交叉凝集现象,21株血清型未定型;药敏结果显示78株分离株对多粘菌素B、磷霉素、克林霉素等的耐药性最强,对头孢拉定、多西环素、呋喃唑酮、氟苯尼考等抗生素最为敏感,并且78株分离株均存在多重耐药性,其中77株耐药5重及以上;动物试验结果显示,RA的分离株致病力普遍较强,而且不同地区分离株、同地区不同分离株之间均存在差异,数株RA分离株的LD₅₀在10⁴-10⁷ CFU不等。【结论】RA在国内流行表现了强致病力及严重耐药情况,本研究结果为更好地预防控制、临床用药及后续致病机制研究提供了参考依据。     

花生根际微生物的分离及高效功能菌株筛选

【背景】花生根际分布着丰富的微生物类群，分离筛选多种功能的高效微生物是研发高效复合菌肥的基础。【目的】从花生根际土壤及根表分离微生物，分析可培养微生物的多样性，筛选高效解有机磷和无机磷、产吲哚乙酸(indole-3-acetic acid, IAA)和铁载体功能的菌株，为研发花生微生物菌肥打下基础。【方法】利用稀释涂布法，从采自山东省栖霞市、平度市、烟台市莱山区 3个样点的花生根际土、根表样品中分离微生物，基于16S rRNA基因序列对其进行系统发育分析，并通过初筛和复筛筛选高效解磷、产IAA和铁载体的菌株。【结果】共分离、纯化、保藏147株菌，其中75株分离自根际土壤，72株分离自根表样品。系统发育分析表明所有的菌分布于放线菌门(Actinomycetota)、芽孢杆菌门(Bacillota)、拟杆菌门(Bacteroidota)和假单胞菌门(Pseudomonadota)这4个门的40个属，优势属为链霉菌属(Streptomyces, 21.77%)、芽孢杆菌属(Bacillus, 16.33%)；根表样品微生物的多样性高于根际样品；共筛选到解有机磷菌株62株，短波单胞菌(Brevundimonas) YTU21021解有机磷能力最强为1.12 mg/L；解无机磷菌株31株，不动杆菌(Acinetobacter) YTU21009解无机磷能力最强为7.04 mg/L；产IAA的菌株63株，肠杆菌(Enterobacter) YTU21054产IAA量最高，达184.19 mg/L；产铁载体细菌7株，伯克氏菌(Burkholderia) YTU21051产铁载体能力最强，A_s/A_r为0.90。【结论】花生根际和根表样品中可培养微生物多样性较为丰富，本研究筛选到的高效功能菌丰富了花生根际功能微生物资源，为后续与高效根瘤菌联合研发花生复合微生物菌肥奠定了基础。     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Die GattungKarschia — Bindeglied zwischen bitunicaten Ascomyceten und lecanoralen Flechtenpilzen?

The genusKarschia, in the earlier sense, including saprophytes and parasites on lichens, has been thought to be a non-lichenized parallel genus of the lichen genusBuellia. Modern workers included it on the one hand inBuellia, on the other hand combined it with bitunicate ascomycetes. It is now proved thatKarschia is heterogeneous and contains but superficially similar members both of the genusBuellia of theLecanorales and of typical or masked bitunicateAscomycetes. Therefore, it can not be regarded as a link betweenLecanorales andDothideales. The type species ofKarschia belongs to theDothideales.

     

Biological control of three floating water weeds,<Emphasis Type="Italic">Eichhornia crassipes,Pistia stratiotes</Emphasis>, and <Emphasis Type="Italic">Salviniamolesta</Emphasis> in the Republic of Congo

Since 1999, four specific weevils (Coleoptera, Curculionidae) were released in the Republic of Congo against three exotic floating water weeds: Neochetina eichhorniae Warner and N. bruchi Hustache against water hyacinth, Neohydronomus affinis Hustache against water lettuce, and Cyrtobagous salviniae Calder and Sands against water fern. Recoveries of exotic weevils were made from all 24 release sites except one, and all four species have established and spread (up to 800 km for water hyacinth weevils). Within a few years of releases, control of water fern and water lettuce was such that fishing and navigation could be resumed, while reductions of water hyacinth populations were only beginning.     

A molecular phylogeny of Hebeloma species from Europe

In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section.     

Demographic characteristics of an intertidal bay goby (Lepidogobius lepidus)

Synopsis In a fourteen month study (May 1976 – June 1977) I examined the following characteristics of an intertidal bay goby (Lepidogobius lepidus) in Morro Bay, California, U.S.A.: annual and seasonal patterns of abundance, age composition and growth rates, survivorship and mortality patterns, and the reproductive cycle for female gobies. Fishes were collected with the aid of quinaldine and otoliths and ovaries removed. Age and growth rates were estimated from otolith annuli using a back calculation formula and a Brody-Bertalanffy growth curve. Mortality rates were derived using the methods of Heincke (1913), Robson & Chapman (1960), mean age, and a catch curve (Ricker 1975). A gonad index was used to describe the annual reproductive cycle. Results indicated that abundance fluctuated seasonally and that these fluctuations appeared to be caused by reproductive emigrations. Bay gobies reached an age of 7+ and a standard length of 87 mm. Growth was relatively constant (6 mm yr⁻¹) until age 5, at which point it began to decline. The mean rates of survivorship, mortality, and instantaneous mortality were 0.75, 0.25, and 0.29 respectively. Mortality rates for individual age classes ranged from 0.13 to 0.51 and increased with age. This stock appears to reproduce mainly during the winter.     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.