Predation upon Hatchling Dinosaurs by a New Snake from the Late Cretaceous of India

Derived large-mouthed snakes (macrostomatans) possess numerous specializations in their skull and lower jaws that allow them to consume large vertebrate prey. In contrast, basal snakes lack these adaptations and feed primarily on small prey items. The sequence of osteological and behavioral modifications involved in the evolution of the macrostomatan condition has remained an open question because of disagreement about the origin and interrelationships of snakes, the paucity of well-preserved early snake fossils on many continental landmasses, and the lack of information about the feeding ecology of early snakes. We report on a partial skeleton of a new 3.5-m-long snake, Sanajeh indicus gen. et sp. nov., recovered from Upper Cretaceous rocks of western India. S. indicus was fossilized in association with a sauropod dinosaur egg clutch, coiled around an egg and adjacent to the remains of a ca. 0.5-m-long hatchling. Multiple snake-egg associations at the site strongly suggest that S. indicus frequented nesting grounds and preyed on hatchling sauropods. We interpret this pattern as “ethofossil” preservation of feeding behavior. S. indicus lacks specializations of modern egg-eaters and of macrostomatans, and skull and vertebral synapomorphies place it in an intermediate position in snake phylogeny. Sanajeh and its large-bodied madtsoiid sister taxa Yurlunggur camfieldensis and Wonambi naracoortensis from the Neogene of Australia show specializations for intraoral prey transport but lack the adaptations for wide gape that characterize living macrostomatan snakes. The Dholi Dungri fossils are the second definitive association between sauropod eggs and embryonic or hatchling remains. New fossils from western India provide direct evidence of feeding ecology in a Mesozoic snake and demonstrate predation risks for hatchling sauropod dinosaurs. Our results suggest that large body size and jaw mobility afforded some non-macrostomatan snakes a greater diversity of prey items than previously suspected on the basis of extant basal snakes.     

Effects of season, sex and body size on the feeding ecology of turtle-headed sea snakes (Emydocephalus annulatus) on IndoPacific inshore coral reefs

In terrestrial snakes, many cases of intraspecific shifts in dietary habits as a function of predator sex and body size are driven by gape limitation and hence are most common in species that feed on relatively large prey and exhibit a wide body-size range. Our data on sea snakes reveal an alternative mechanism for intraspecific niche partitioning, based on sex-specific seasonal anorexia induced by reproductive activities. Turtle-headed sea snakes (Emydocephalus annulatus) on coral reefs in the New Caledonian Lagoon feed entirely on the eggs of demersal-spawning fishes. DNA sequence data (cytochrome b gene) on eggs that we palpated from stomachs of 37 snakes showed that despite this ontogenetic stage specialization, the prey comes from a taxonomically diverse array of species including damselfish (41 % of samples, at least 5 species), blennies (41 %, 4 species) and gobies (19 %, 5 species). The composition of snake diets shifted seasonally (with damselfish dominating in winter but not summer), presumably reflecting seasonality of fish reproduction. That seasonal shift affects male and female snakes differently, because reproduction is incompatible with foraging. Adult female sea snakes ceased feeding when they became heavily distended with developing embryos in late summer, and males ceased feeding while they were mate searching in winter. The sex divergence in foraging habits may be amplified by sexual size dimorphism; females grow larger than males, and larger snakes (of both sexes) feed more on damselfish (which often lay their eggs in exposed sites) than on blennies and gobies (whose eggs are hidden within narrow crevices). Specific features of reproductive biology of coral reef fish (seasonality and nest type) have generated intraspecific niche partitioning in these sea snakes, by mechanisms different from those that apply to terrestrial snakes.     

Perils of ingesting harmful prey by advanced snakes

The advanced snakes (Alethinophidia) include the extant snakes with a highly evolved head morphology providing increased gape and jaw flexibility. Along with other physiological and morphological adaptations, this allows them to immobilize, ingest, and transport prey that may be disproportionately large or presents danger to the predator from bites, teeth, horns, or spines. Reported incidents of snakes failing to consume prey and being injured or killed during feeding mostly reflect information in the form of natural-history notes. Here we provide the first extensive review of such incidents, including 101 publications describing at least 143 cases of mortality (including six of ‘multiple individuals’) caused by ingestion or attempted consumption of injurious prey. We also report on 15 previously unpublished injurious feeding incidents from the USA, Austria, and Bulgaria, including mortality of five juvenile piscivorous dice snakes (Natrix tessellata) from a single location. Occurrences are spread across taxa, with mortality documented for at least 73 species from eight families and 45 genera. Incidents were generally well represented within each of three major categories: oversized prey (40.6%), potentially harmful prey (40.6%), and predator's behavioural/mechanical errors (18.9%). Reptile (33%) and fish (26%) prey caused disproportionately high mortality compared to mammals (16%). Feeding can be dangerous throughout a snake's life, with the later stages of feeding likely being more perilous. The number of reports has increased over time, and the data seem biased towards localities with a higher number of field-working herpetologists. We propose a standardized framework, comprising a set of basic information that should ideally be collected and published, and which could be useful as a template for future data collection, reporting, and analyses. We conclude that incidents of mortality during feeding are likely to be more common than previously assumed, and this hypothesis has implications for the ecology of persistence where populations are impacted by changing trophic environments.     

Diversity of bacteria associated with grassland soil nematodes of different feeding groups

The bacterial diversity associated with soil nematodes and its relationship with their feeding habits are as yet poorly understood. In the present study the diversity and abundance of bacteria from nematodes and their surrounding soil were analysed and compared. The nematodes were collected from a grassland soil and sorted into bacterial, fungal, plant, predatory and omnivore feeding groups and assigned to taxonomic groups. Total DNA was extracted from the nematodes and partial bacterial 16S rRNA genes were PCR amplified, cloned and sequenced. The abundance and composition of bacterial taxa differed between and within feeding groups. The lowest bacterial diversity was found in the predatory nematodes Prionchulus sp., whereas the highest bacterial diversity was associated with the bacterial-feeding nematode Acrobeles sp. The soil had a more diverse bacterial community than the communities found in the nematode groups. The 16S rRNA gene sequences of bacteria associated with nematodes did not overlap with those detected in soil as determined using the cloning screening approach. However, bacterial sequences identified from nematodes could be detected in the soil with targeted PCR. Our data suggest that the nematodes do not feed on the most abundant bacteria present in soil. Furthermore, several nematodes contained suspected bacterial symbionts and parasites.     

原羚属分类地位研究兼论中国羚羊的分类

中国羚羊类动物在世界羚羊类动物中有着特殊的地位,其中普氏原羚、藏原羚和藏羚是中国特有的珍稀物种,普氏原羚是极度濒危动物.开展中国羚羊类动物的分类和进化研究是当务之急.本研究利用形态特征、头骨测量及线粒体DNA的12S rRNA(440 bp)和16S rRNA(590 bp)对原羚属的分类地位及中国其他几种羚羊分类地位进行了探讨,发现对质量性状和数量性状数据的聚类分析的结果差异大,而且质量性状的聚类结果比较符合传统的分类系统.分子分类也得到相似结果,但在属下的分析存在较大差异.7种牛科动物的12S rRNA和16S rRNA序列差异分别为0.2%～7.1%和0.3%～8.4%.系统进化分析表明原羚属3种羚羊形成单系群,且蒙古瞪羚与普氏原羚的关系较藏原羚与普氏原羚的关系近.赛加羚应归宿于羚羊亚科,而不是与羊亚科的藏羚形成独立的赛加羚亚科.原羚属的进化可能与青藏高原的隆起有关.     

基于12S,16S和28S rRNA基因序列的中国小毛瓢虫属系统发育分析

【目的】小毛瓢虫属Scymnus Kugelann昆虫主要捕食蚜虫、蚧虫等害虫,是一类经济上重要的天敌昆虫。目前针对小毛瓢虫属的系统发育研究尚属空白,亚属之间的系统演化关系尚不明确,为了建立合理的分类系统,亟需对小毛瓢虫属的亲缘关系进行研究和探讨。【方法】以华南农业大学馆藏的小毛瓢虫属5亚属共44种为研究对象,采用PCR技术对12S, 16S和28S rRNA基因的部分序列进行扩增;运用MEGA 7.0分析了小毛瓢虫属内12S, 16S和28S rRNA基因的碱基组成,基于K2P模型计算了小毛瓢虫属44种的种间遗传距离;采用最大似然法(maximum-likelihood, ML)和贝叶斯推断法(Bayesian-inference, BI)构建该属的系统发育树。【结果】扩增获得小毛瓢虫属44种的12S rRNA基因序列平均长度为356 bp, 16S rRNA基因序列平均长度为351 bp, 28S rRNA基因序列平均长度为315 bp;序列分析表明,12S rRNA基因的A, T, G和C平均含量分别为38.8%, 43.5%, 11.9%和5.8%, 16S rRNA基因的A, T, G和C平均含量分别为37.6%, 40.3%, 14.4%和7.7%, 28S rRNA基因的A, T, G和C平均含量分别为26.7%, 18.3%, 31.4%和23.5%;基于联合序列分析的种间遗传距离为0.004～0.276,平均遗传距离为0.115。系统发育分析结果表明,小毛瓢虫属为单系起源,而小毛瓢虫亚属Scymnus(Scymnus) Kugelann、毛瓢虫亚属Scymnus(Neopullus) Sasaji、小瓢虫亚属Scymnus(Pullus) Mulsant和拟小瓢虫亚属Scymnus(Parapullus) Yang均为并系起源。【结论】基于12S, 16S和28S rRNA基因序列的小毛瓢虫属系统发育分析显示传统的形态学分类体系与基于分子数据分析的结果部分不一致,这表明应该对该属内各亚属的鉴别特征进行全面检视,筛选并确立各亚属的形态指标,同时也表明该属内的亚属分类单元需重新厘定。     

新疆塔里木盆地可培养嗜盐放线菌系统发育多样性

应用纯培养手段和基于16S rRNA基因序列的系统发育分析,对从塔里木盆地高盐环境土壤样品中分离的18株可培养嗜盐放线菌多样性进行了研究.实验结果表明,18株嗜盐放线菌可3个(GlycomycetaceaePseudonocardineae和Nocardiopsaceae),在有效发表的5个属的嗜盐放线菌中有4个属的嗜盐放线菌被分离到.多数菌株属于Actinopolyspora属(38.9%),Nocardiopsis属(27.8%)和Streptomonospora属(22.2%),是塔里木盆地高盐环境中嗜盐放线菌的优势类群.这些分离菌株中,菌株YIM 92370与最近种的相似性为92%,在Glycomycetaceae科内形成一个独立的分支,极有可能代表Glycomycetaceae科的一个新属.研究结果表明塔里木盆地高盐环境中存在有较为丰富的嗜盐放线菌系统发育多样性,并且潜藏着新类型的放线菌资源.     

Prey Transport Mechanisms in Blindsnakes and the Evolution of Unilateral Feeding Systems in Snakes

Most snakes ingest and transport their prey via a jaw ratchetingmechanism in which the left and right upper jaw arches are advancedover the prey in an alternating, unilateral fashion. This unilateraljaw ratcheting mechanism differs greatly from the hyolingualand inertial transport mechanisms used by lizards, both of whichare characterized by bilaterally synchronous jaw movements.Given the well-corroborated phylogenetic hypothesis that snakesare derived from lizards, this suggests that major changes occurredin both the morphology and motor control of the feeding apparatusduring the early evolution of snakes. However, most previousstudies of the evolution of unilateral feeding mechanisms insnakes have focused almost exclusively on the morphology ofthe jaw apparatus because there have been very few direct observationsof feeding behavior in basal snakes. In this paper I describethe prey transport mechanisms used by representatives of twofamilies of basal snakes, Leptotyphlopidae and Typhlopidae.In Leptotyphlopidae, a mandibular raking mechanism is used,in which bilaterally synchronous flexions of the lower jaw serveto ratchet prey into and through the mouth. In Typhlopidae,a maxillary raking mechanism is used, in which asynchronousratcheting movements of the highly mobile upper jaws are usedto drag prey through the oral cavity. These findings suggestthat the unilateral feeding mechanisms that characterize themajority of living snakes were not present primitively in Serpentes,but arose subsequently to the basal divergence between Scolecophidiaand Alethinophidia.     

Dissecting the major American snake radiation: A molecular phylogeny of the Dipsadidae Bonaparte (Serpentes,Caenophidia)

The Dipsadidae contains more than 700 extant species belonging to 92 genera and is the largest family of American snakes. In this work, we built a data set including two mitochondrial genes (12S and 16S rRNA) for 125 dipsadid taxa belonging to 59 genera, in order to gain further insights on the phylogenetic relationships of this large group at the subfamilial and generic levels. Among dipsadines, the monotypic genus Nothopsis is the sister-group to Leptodeira. Among xenodontines, the monophyly of seven previously recognized tribes (Alsophiini, Elapomorphini, Hydropsini, Philodryadini, Pseudoboini, Tachymenini and Xenodontini) is confirmed. Among Xenodontini, the genus Liophis is paraphyletic with respect to Erythrolamprus and Umbrivaga and workers should be aware of the inadequacy of the current taxonomy. Finally, the following genera could not confidently be allocated to the above tribes: Caaeteboia, Echinantera and Taeniophallus, Tropidodryas, Manolepis and Pseudalsophis, Xenopholis, Psomophis, Hydrodynastes, Conophis and Crisantophis.     

Meal Size Effects on Antipredator Behavior of Hatchling Trinket Snakes, Elaphe helena

Current foraging models limit the decision‐making process of animals to the food searching and consuming phase. The post‐consummatory phase of feeding may influence optimal meal size for some species as a morphologic change often results from feeding. In snakes, a single prey item can lead to abrupt increases in body mass, thus influencing locomotor performance. Identifying factors affecting locomotor performance can help predict behaviors that should maximize an animal's chance of evading predators. Although many snakes ingest large percentages of their body mass, not much work has examined the post‐consummatory effects of ingesting bulky prey differing in relative mass. I examined the locomotor performance and antipredator tactics of hatchling trinket snakes (Elaphe helena) after subjecting snakes to mice prey varying by relative mass differences of 20–35%, 50–59% or 70–79% of an individual hatchling's body mass. Snakes in treatment groups were compared with snakes in a control group (0%). Meal size‐affected locomotor parameters such as burst speed, endurance, and endurance times for hatchlings that ingested 50–59% and 70–79% of their body mass (p < 0.001). Recent feeding also affected the types of antipredator modes employed. Hatchlings in the 0% and 20–35% treatments exhibited behaviors that were categorized as active and threatening, while hatchlings in the 50–59% and 70–79% treatments exhibited stationary, neutral, and cryptic behaviors. Although snakes may become more reclusive following a meal, this study demonstrates that relative prey mass affects the ability of hatchling trinket snakes to flee from a predator. In turn, these results suggest that the post‐consummatory effects of foraging should be considered in optimal foraging models for organisms that consume a substantial portion of their body mass during a single feeding.     

Feeding Strategies in Marine Snakes: An Analysis of Evolutionary, Morphological, Behavioral and Ecological Relationships

Analysis of 1,063 stomach contents from 39 species of sea snakesindicates that about one-third of the shallow, warm, marine,Indo-Australian fish families are preyed upon by sea snakes.Families of eels and gobies are taken by the greatest numbersof snake species. Most species of sea snakes feed on fish familieswhose members are relatively sedentary, dwelling along the bottom,within burrows or reef crevices. With one exception, a fishegg-eating specialization found uniquely in the Aipysurus-Emydocephaluslineage, the dietary habits of sea snakes cannot be categorizedaccording to the snakes' three phylogenetic lineages. Eels,mullet-like, rabbitfish-like and goby-like fish forms are takenby all three lineages. Two or three snake species are generalists,and numerous ones specialize on eels, goby-like fish or catfish.There are differences among sea snake species in the relationshipbetween snake neck girth and the maximum diameter of the prey;in the relationships of both snake gape measurements and fanglength, to the type of prey taken; and in the relationship ofsnake shape and body proportions to the prey selected. Severalmodes of feeding have been observed among sea snakes: feedingin nooks and crannies in the bottom or in reefs, cruising nearthe bottom, and feeding in drift lines. Analysis of percentdigestion of stomach contents and projections backward to thetimes of prey capture provides evidence for feeding periodicity.The greatest amount of diet overlap is for two species of seasnakes which do not both occur at the same locality. Where speciesdo co-occur, diet overlap index values are lower. The numbersof species present as well as their relative abundances varyamong localities as does the relative importance of generalists,eel-eaters, egg-eaters and other specialized feeders.     

Dietary Correlates of the Origin and Radiation of Snakes

Stomach analyses of living families and of a fossil containingprey were used to address possible dietary correlates of thehistory of snakes. Aniliids, morphologically primitive amongliving snakes, feed on relatively heavy, elongate vertebrates.Large aniliids eat larger prey than do small individuals but,as in advanced snakes, they also take small items. Living boids,structurally intermediate between aniliids and advanced snakes,feed on relatively heavy prey of a much greater variety of shapesthan do aniliids. An Eocene fossil that might be a boid containsa relatively large crocodilian in its gut. These findings, previousstudies, and morphological considerations suggest that veryearly snakes used constriction and powerful jaws to feed onelongate, heavy prey. This would have permitted a shift fromfeeding often on small items to feeding rarely on heavy items,without initially requiring major changes in jaw structure relativeto a lizard-like ancestor. Subsequent morphological changescould then have allowed boids to utilize a broad range of preytypes, including many of those currently eaten by advanced snakes.More recent dietary themes include the consumption of even heavierprey by highly venomous elapids and viperids, and frequent feedingon relatively small items by some other advanced snakes.     

Feeding with speed: prey capture evolution in cichilds

The diversity of both the locomotor and feeding systems in fish is extensive, although little is known about the integrated evolution of the two systems. Virtually, all fish swim to ingest prey and all open their buccal cavity during prey capture, but the relationship between these two ubiquitous components of fish feeding strikes is unknown. We predicted that there should be a positive correlation between ram speed (RS) and maximum gape (MG) because the accuracy of a predatory strike goes down with an increase in RS and fish with larger mouths eat larger, more evasive prey. For 18 species of neotropical cichlids, we used phylogenetic-independent contrasts to study the relationship between the predator closing speed (RS) and mouth size (MG) during prey capture. To provide a robust comparative framework, we augmented existing phylogenetic information available from the mitochondrial cytochrome b gene with sequences from the S7 nuclear ribosomal intron for these species. Then, we captured high-speed (500 images per second), lateral view feeding sequences of each species by using a digital video camera and measured both RS and MG. Uncorrected species values of MG and RS were positively and significantly correlated. When accounting for any of the set of phylogenetic relationships recovered, the independent contrasts of RS and MG remained significantly, and positively, correlated. This tight evolutionary coupling highlights what is likely a common relationship between locomotor behaviour and feeding kinematics in many organisms.     

The functional meaning of “prey size” in water snakes (Nerodia fasciata, Colubridae)

The evolutionary success of macrostomatan (enlarged-gape) snakes has been attributed to their ability to consume large prey, in turn made possible by their highly kinetic skulls. However, prey can be “large” in several ways, and we have little insight into which aspects of prey size and shape affect skull function during feeding. We used X-ray videos of broad-banded water snakes (Nerodia fasciata) feeding on both frogs and fish to quantify movements of the jaw elements during prey transport, and of the anterior vertebral column during post-cranial swallowing. In a sample of additional individuals feeding on both frogs and fish, we measured the time and the number of jaw protractions needed to transport prey through the buccal cavity. Prey type (fish vs. frog) did not influence transport kinematics, but did influence transport performance. Furthermore, wider and taller prey induced greater movements of most cranial elements, but wider prey were transported with significantly less anterior vertebral bending. In the performance trials, heavier, shorter, and wider prey took significantly more time and a greater number of jaw protractions to ingest. Thus, the functional challenges involved in prey transport depend not only upon prey mass, but also prey type (fish vs. frog) and prey shape (relative height, width and length), suggesting that from the perspective of a gape-limited predator, the difficulty of prey ingestion depends upon multiple aspects of prey size.     

从线粒体基因探讨中国大头蛙群的分类及其属内地位

Partial sequences of the mitochondrial 12S rRNA and 16S rRNA gene were determined for 8 populations of three species of Chinese Limnonectes, and aligned with the published sequences of Limnonectes from other parts of the world. When Nanorana parker, Paa boulengeri, Fejervarya limnocharis and Hoplobatrachus rugulosus was used as outgroup taxa (Accession Nos. AY158705, AY313685, AF206111, AF206491, AY322311). The sequences of the 12S rRNA and 16S rRNA genes totaled 950 nueleotide positions with gaps including 510 variable sites. We reconstructed phylogenetie trees using Clustal X 1.8, Mega 2.1 and PHYLIP 3.5e software, and using the maximum parsimony and maximum likelihood methods, respectively. Our analyses suggest that these fanged frogs from China are another monophyletie group in addition to the four monophyletie groups identified by previous studies. The Chinese Limnonectes were grouped into three elades (BCL 55% ). The first elade contains one species (BCL 100% ), from a population of Limnoneetes fragilis from Hainan Province. The second contains four individuals (BCL 100% ), i. e. two populations of Limnonectes kuhlii from Yunnan Province. The third contains one species (BCL 100% ), i. e. five populations of Limnonectes fujianensis from Fujian Province and 1 from Taiwan Province. The resulted phylogenetie trees indicate L. fragilis is basal to L. kuhlii L. fujianensis 。     

基于16S rRNA基因序列对织纹螺属的分子系统学分析

研究利用线粒体16S rRNA基因序列片段,对织纹螺属6亚属11种动物进行分子系统学分析。结果显示,种内遗传距离(0～0.007)与种间遗传距离(0.019～0.088)无重叠,这表明线粒体16S rRNA基因能较好地反映织纹螺种间的亲缘关系; 而亚属内遗传距离(0.018～0.031)与亚属间遗传距离(0.028～0.083)存在重叠,表明线粒体16S rRNA基因不能对一些贝壳形态相似的亚属进行区分。同时,确定了疑难种灰白织纹螺Nassarius(Zeuxis)canaliculatum的分类地位,并与相似种西格织纹螺N.(Z.)siquijorensis进行了对比; 确认了秀丽织纹螺Nassarius(Hima)festivus应属于Hima亚属;建议保留单型亚属Varicinassa的有效性。     

两种培养基对对虾苗池海洋蛭弧菌的分离及其多样性分析

【目的】明确海水(Sw)和聚蛋白胨20(Pp20)两种双层琼脂培养基对海洋蛭弧菌的分离计数效果,了解对虾苗池可培养海洋蛭弧菌多样性。【方法】采用双层平板法,比较Sw和Pp20培养基对2株海洋蛭弧菌和对虾苗池未知海洋蛭弧菌的计数效果。通过宿主范围测试和16S rRNA基因序列分析评估两种培养基分离苗池海洋蛭弧菌的多样性。【结果】宿主菌含量高时,Sw培养基对两株已知海洋蛭弧菌的计数值均显著高于(P0.05)Pp20。Sw和Pp20培养基从同一苗池水样分别分离得到21和22株蛭弧菌。根据宿主裂解范围差异,43株分离物可分为15种裂解模式,其中Sw和Pp20培养基各分离到12和8种。16S rRNA基因序列分析表明,所有分离物都被鉴定为噬菌弧菌属(Bacteriovorax)菌株,并可分为6个类群,Sw和Pp20培养基分别分离到6和4个类群。【结论】Sw培养基在分离计数海洋蛭弧菌及其多样性检测上效果均优于Pp20;对虾苗池可培养海洋蛭弧菌具有较高多样性,并以类群XIII、X及一个潜在新类群为优势种群。     

Polymorphism of mtDNA regions in brown hare (Lepus europaeus) populations from Vojvodina (Serbia and Montenegro)

It is well known that there is heterogeneity of mitochondrial DNA (mtDNA) within and among natural populations of same species. The polymorphism level of particular regions of mtDNA gives valuable results in detection of population genetic structure. The aim of this paper was to detect polymorphism of three mtDNA regions: cytochrome oxidase I (COI), Control region, and 12S/16S rRNA, by the mtDNA RFLP-PCR method, in three Lepus europaeus populations from Vojvodina province (Serbia and Montenegro). Polymorphism was detected within the two regions, COI and Control region, while 12S/16S rRNA region was monomorphic in all 77 individuals. Eight haplotypes were detected in the brown hare population in Vojvodina, and three were unique for the Srem brown hare population.     

抗菌和细胞毒活性海洋细菌的筛选及其次生代谢基因证据

从不同海域的海水、海泥和海洋生物中分离海洋细菌,利用琼脂扩散法和MTT法对细菌培养液的乙酸乙酯提取物进行了抗菌和细胞毒活性筛选,并对具有细胞毒活性的细菌菌株进行了16SrRNA系统发生学分析和多聚酮合酶(PKSⅠ型)、非核糖体肽合成酶(NRPS)的筛选。结果显示,在分离到的346株海洋细菌中,42株细菌具有抗菌活性,12株具有细胞毒活性。对12株具有细胞毒活性的细菌菌株进行了16SrRNA系统发生学分析,它们分别属于Agrobacterium,Pseudoalteromons,Bacillus,Paracoccus,Rheinheimera,Aerococcus,Exiguobacterium和Alteromonas8个属。对这12株具有细胞毒活性的细菌菌株进行进一步的PKS和NRPS筛选,得到了4株含有PKSⅠ型的KS结构域或NPRS的A结构域的海洋细菌,为从聚酮和非核糖体肽等生物合成途径去深入研究其次生代谢产物提供了基因学的证据。     

艾丁嗜盐小盒菌B2菌株16S rRNA核苷酸序列

艾丁嗜盐小盒菌B2菌株(Haloarcula aidinensis, strain B2)16Sr RNA的核苷酸序列已以双脱氧核苷酸链终止法确定。该菌16Sr RNA显示出了典型的古生物类(Archaea)特性。虽然艾丁嗜盐小盒菌B2菌株在序列方面更接近细菌类(Bacteria)的16SrRNA,但它的序列也显示出与真核生物类(Eucarya)的某些特殊的相似性。在序列和结构方面,该菌与细菌类或真核生物类之间的相似程度要高于细菌类与真核生物类之间的相似程度。另外,该菌16SrRNA的序列与其它嗜盐菌序列相比较支持了以前的结论,即艾丁嗜盐小盒菌B2菌株应属于嗜盐小盒菌属(Haloarcula)的一新种。