澜沧江中下游篦齿苏铁种群结构及其保护对策

对澜沧江中下游糯扎渡水电站工程枢纽区和库区内篦齿苏铁的生境、种群结构进行调查研究。结果表明,篦齿苏铁在澜沧江干流的两岸分布不均匀,右岸占48.37%,左岸占4.26%,支流占46.37%;主要生长在落叶季雨林下,以半阴半阳坡较多,占总株数401株的47.85%。调查区域内篦齿苏铁种群密度很低,平均约1株/hm2。由于人为采挖严重,导致其种群大小级结构不完整,成年个体较少,缺乏Ⅲ级个体,以Ⅰ级、Ⅱ级幼小个体较多,占32.21%。种群内开花结实植株少,仅发现5株开花,2株结实,但其单株自然结实率较高。目前该种群面临的威胁有：人为采挖;人类生产和建设活动使其生境丧失及生境退化严重;啮齿动物的啃食。使该区域苏铁种群密度急剧减小的主要原因是各种人为干扰,而非自然因素。指出应加大对篦齿苏铁野生资源的调查和保护力度,就地保护和迁地保护相结合,并开展人工繁殖、遗传多样性和生理生态方面的研究,以便更加科学、合理地制定其保护措施。     

栉江珧研究现状及开发利用前景

对广泛分布于温、热带近海海域的大型深水贝类栉江珧的分类地位和地理分布作了介绍，并就栉江珧栖息状况，对水温、盐度、pH、溶解氧等各种环境因子适应性的生态习性作了详细描述。论述了水温对栉江珧的生长、性腺周期发育的影响。对栉江珧人工繁育过程中的亲贝暂养、催产及幼体培育的技术和养殖现状进行了总结。简要概述了江珧科物种同工酶的研究进展，并对栉江珧资源保护及可持续利用和今后研究方向作了探讨。     

栉江珧消化系统组织学与组织化学的研究

运用组织学和组织化学方法对栉江珧消化系统的结构和功能进行了研究.栉江珧消化管的粘膜上皮由纤毛柱状细胞和杯状细胞组成,唇瓣、中肠和上行肠的上皮层还有嗜酸性粒分泌细胞;消化盲囊的腺上皮由分泌细胞和消化(吸收)细胞组成.皮下结缔组织中富含血腔隙,结缔组织和血腔隙中有"颗粒细胞".食道、胃、中肠、晶杆囊及消化盲囊能分泌消化酶,对食物进行消化和吸收;结缔组织、"颗粒细胞"也参与了食物的消化吸收.唇瓣、食道、晶杆囊和中肠的上皮细胞及结缔组织中的"颗粒细胞"内含铁,结缔组织中含钙.     

温度和盐度对栉江珧耗氧率和排氨率的影响

[目的]探讨温度和盐度对栉江珧耗氧率（OR）和排氨率（NR）的影响。[方法]设置5个温度梯度和5个盐度梯度，测定温度和盐度对栉江珧OR和NR的影响。[结果]在18～34℃范围内，栉江珧单位体重OR和NR均随温度升高而增加，分别为260．82～585．90μg/（g·h）和26．32～42．19μg/（g·h），OR和NR与温度的相关方程分别为：ORT=-16．14lt^2＋197．58t＋89．29l（R^2=0．9738）；NRT=-0．6981t^2＋8．4677t＋17．792（R^2=0．9733）：在21～41盐度范围内，栉江珧单位体重OR和NR先随盐度增加而降低，在盐度31时达最小值，然后随盐度增加而升高，其变化分别为：575．82～734．40μg/（g·h）和36．78～54．45μg/（g·h），0R和NR与盐度之间的相关方程分别为：ORs=37．929s^2一214．27s＋867．6（R^2=0．9872）；NRs=3．5442s^2-19．748s＋62．08（R^2=0．9461）；表明在正常盐度下，贝体能量消耗较低。[结论]温度和盐度对栉江珧OR和NR均有显著影响，     

篦齿苏铁栽培养护技术

篦齿苏铁树干高大,树形优美,全年具有大型而美丽的浓绿叶丛,具有很高的园林观赏价值,但栽培养护难度较大,容易发生病虫害和腐烂等,对种植措施的要求也较特殊。文章根据实践经验,对篦齿苏铁种植前树体处理、种植坑准备、日常护理、肥水管理、病虫害防治等方面作了详细的阐述。     

Tracking public interest and perceptions about smalltooth sawfish conservation in the USA using Instagram

1. The population of smalltooth sawfish (Pristis pectinata) in the USA was listed as endangered under the US Endangered Species Act in 2003. Based on objectives identified in the Smalltooth Sawfish Recovery Plan, an interdisciplinary team developed a variety of outreach efforts and products to educate the public and promote sawfish conservation. These include safe viewing, handling, release, and reporting guidelines for boaters, divers, and anglers that may interact with the species.
2. The usefulness of monitoring social media to track public interest and perceptions of smalltooth sawfish was investigated via Instagram posts mentioning sawfish encounters in the USA. We aimed to identify how current outreach efforts and messaging can be improved and expanded to better inform the public and promote positive change in their behaviour to further protect smalltooth sawfish.
3. All encounters occurred in Florida waters and the trend of sawfish-related Instagram posts increased congruently with traditionally reported sawfish encounters from 2012 to 2019. The number of Instagram users who indicated that they reported their encounter or that any sawfish encounter should be reported has increased, suggesting outreach efforts have gained traction and that some members of the public are actively promoting sawfish conservation through encounter reporting. The overall tone, and thereby public perception of and attitude towards sawfish, was largely positive.
4. Though social media can be used to guide outreach initiatives and provides a platform for researchers to engage large public audiences, future research efforts should include electronic surveys within the recreational, commercial, diving, and angling communities. Additionally, social media posts should be compared with traditionally reported encounters, and media professionals working with scientists should focus on increasing the utility of social media as a way to collect encounter reports and create engaging educational content to be included with continued outreach efforts throughout the south-eastern USA.

     

Use of marine by‐product meals in diets for juvenile longfin yellowtail Seriola rivoliana

A 60‐day feeding trial to determine the nutritional value of marine by‐product meals in diets for longfin yellowtail Seriola rivoliana juveniles (48.1 ± 0.6 g initial weight) was conducted. Five diets were evaluated: a reference diet (RD; 500 g kg^?1 CP, 130 g kg^?1 L), containing 500 g kg^?1 of fish meal (FM); three experimental diets with 125 g kg^?1 of shrimp head (SM), Catarina scallop viscera (CM) or Pen shell viscera (PM) meals; and one diet (SCP) containing 125 g kg^?1 of each of the experimental meals, to partially replace FM. Survival was not significantly affected by any treatment. Individual weight gain per day was high for the PM (5.3 ± 0.51 g d^?1) and SM (4.7 ± 0.32 g d^?1) diets, being significantly higher than the RD (3.5 ± 0.23 g d^?1) and the other treatments (<1.2 g d^?1). Feed intake was high in PM and SM diets, and very low in SCP and CM diets. Biochemical and haematological parameters were similar among treatments RD, PM and SM, while fish fed CM and SCP exhibited lower levels of total protein, cholesterol, haematocrit and haemoglobin. The results indicate that SM or PM can be used to partially replace FM in diets for yellowtail juveniles.     

栉江珧和近江牡蛎的精子超低温冷冻保存

栉江珧(Atrina pectinata)和近江牡蛎(Crassostrea rivularis)是我国重要的海产经济贝类,建立其精子冷冻保存技术及精子冷冻库,对种质资源的保护和遗传育种具有重要意义.本研究对其精子冷冻保存过程中冷冻剂种类和浓度的选择、冷冻程序、平衡时间、保存体积、精液稀释方式、保存时间等多个影响因素进行了比较筛选,并利用显微镜直接检测和曙红Y(eosin Y)染色检测结合的方式检验精子存活率.结果表明,二甲亚砜(dimethyl sulfoxide,DMSO)作为抗冻剂的保存效果要明显优于甘油(glycerol,Gly),终浓度为8％～10％的二甲亚砜保存效果最好,其栉江珧和近江牡蛎精子活率均可达60％以上,而甘油保护下精子活率小于40％.精液的稀释方式采用将抗冻液等分为3份,依次与精液混合,每次间隔8 min,整个过程约30 min;此种精液稀释方式与一次性混合方式相比,精子活率可提高约30％.稀释后精液需要在4℃下平衡15～25 min,平衡样品与直接冷冻样品相比,精子活率提高约50％.精液降温程序为在样品投入液氮前,于液氮面以上15 cm处停留5 min,5 cm处停留10 min,精子活率可达60％以上;而未经此降温程序直接投入液氮中的样品精子活率接近0.与此降温程序相对应的样品冷冻体积在1.0～1.4 mL范围内为宜.冷冻180 d内复苏的精子活率由90％左右(鲜精)下降至60％左右,180 d后精子活率下降至56％左右.研究结果为栉江珧和近江牡蛎精子超低温冷冻保存、双壳类种质保护和遗传育种提供了理论和技术依据.     

栉江珧同工酶多态性的分析

采用垂直板聚丙烯酰胺梯度凝胶电泳对栉江珧(Atrina pectinata Linnaeus)消化盲囊进行了5种酶(SOD、EST、MDH、ME、LDH)的同工酶分析。结果表明不同个体的同工酶表达呈现多态现象，个体间酶带带型既有相一致的共同特征谱带，又有较多的变异．5种酶均可把样品大致区分为差异明显的2种或3种类型，而且酶谱类型与形态类型基本对应，同工酶表达上的多样性表明栉江珧种内在生化遗传上存在较大的变异，具有较丰富的遗传多态性。     

人工诱导栉江珧雌核发育的初步研究

利用紫外线诱导进行栉江珧(Atrina pectinata)雌核发育单倍体的研究,用强度为2 561μW/(cm2.s)的紫外线(254nm)照射不同时间的精子与正常卵子受精展开实验。结果发现随照射时间的增加,卵裂率、早期胚胎存活率和D型幼虫发生率总体呈下降趋势,遗传失活的精子与正常卵子受精后其胚胎发育至D型幼虫前期停止。经紫外线照射的精子受精后所产生的单倍体胚胎发育速度慢于正常受精所产生的二倍体胚胎,各照射组均出现非整倍体。40 s照射组中卵裂率达到51.2%,D型幼虫发生率为0,单倍体率最高,达到36.8%,出现“Hertwig效应”。由于雌核发育单倍体的有效诱导既需要精子遗传物质失活、又需要保证较高的卵裂率,因而在强度2 561μW/(cm2.s)的紫外线下照射40 s是获得栉江珧雌核发育单倍体的最佳条件。