Pelagostrobilidium liui n. sp. (Ciliophora,Choreotrichida) from the Coastal Waters of Northeastern Taiwan and an Improved Description of Pelagostrobilidium minutum Liu et al., 2012

The number of somatic kineties in Pelagostrobilidium ranges from 4 to 6 according to the present state of knowledge. This study investigates Pelagostrobilidium liui n. sp. using live observation, protargol stain, and small subunit rDNA data sequencing. Pelagostrobilidium liui n. sp. is characterized by having a spherical‐shaped body, four somatic kineties, with kinety 2 spiraled around the left side of body, about six elongated external membranelles, and invariably no buccal membranelle. It differs from its most similar congener, Pelagostrobilidium minutum Liu et al., 2012 , in (i) cell shape; (ii) macronucleus width; (iii) oral apparatus; (iv) anterior orientation of kinety 2; (v) location where kinety 2 commences; (vi) arrangement of kinety 1; (vii) distance between the anterior cell end and the locations where kineties commence; and (viii) the presence of 12 different bases (including two deletions) in the small subunit rDNA sequences. The diagnosis of P. minutum Liu et al., 2012 is also improved to include the following new characteristics: invariably four somatic kineties; kineties 2 and 4 alone commence at the same level; kinety 2 originates from right anterior cell half on ventral side, extends sinistrally posteriorly, over kinety 1, around left posterior region, terminates near posterior cell end on dorsal side; kinety 1 commences below anterior third of kinety 2.     

Influence of rumen protozoa on methane emission in ruminants: a meta-analysis approach

A meta-analysis was conducted to evaluate the effects of protozoa concentration on methane emission from ruminants. A database was built from 59 publications reporting data from 76 in vivo experiments. The experiments included in the database recorded methane production and rumen protozoa concentration measured on the same groups of animals. Quantitative data such as diet chemical composition, rumen fermentation and microbial parameters, and qualitative information such as methane mitigation strategies were also collected. In the database, 31% of the experiments reported a concomitant reduction of both protozoa concentration and methane emission (g/kg dry matter intake). Nearly all of these experiments tested lipids as methane mitigation strategies. By contrast, 21% of the experiments reported a variation in methane emission without changes in protozoa numbers, indicating that methanogenesis is also regulated by other mechanisms not involving protozoa. Experiments that used chemical compounds as an antimethanogenic treatment belonged to this group. The relationship between methane emission and protozoa concentration was studied with a variance−covariance model, with experiment as a fixed effect. The experiments included in the analysis had a within-experiment variation of protozoa concentration higher than 5.3 log₁₀ cells/ml corresponding to the average s.e.m. of the database for this variable. To detect potential interfering factors for the relationship, the influence of several qualitative and quantitative secondary factors was tested. This meta-analysis showed a significant linear relationship between methane emission and protozoa concentration: methane (g/kg dry matter intake)=−30.7+8.14×protozoa (log₁₀ cells/ml) with 28 experiments (91 treatments), residual mean square error=1.94 and adjusted R²=0.90. The proportion of butyrate in the rumen positively influenced the least square means of this relationship.     

Morphological and Molecular Characterization of a New Species of Stephanopogon,Stephanopogon pattersoni n. sp.

Stephanopogon is a taxon of multiciliated protists that is now known to belong to Heterolobosea. Small subunit ribosomal DNA (SSU rDNA) phylogenies indicate that Stephanopogon is closely related to or descended from Percolomonas, a small tetraflagellate with a different feeding structure, thus these morphologically dissimilar taxa are of ongoing evolutionary interest. A new strain of Stephanopogon, KM041, was cultured, then characterized by light microscopy, electron microscopy, and SSU rDNA sequencing. KM041 is 18–35 μm (mean 26.8 μm) long, with six main ventral ciliary rows, one ventro‐lateral ciliary row, and three anterior barbs. It closely resembles Stephanopogon minuta Lei et al. 1999 in morphology, and is very closely related to an extinct culture “S. aff. minuta”, yet is markedly dissimilar in SSU rDNA sequence from a different isolate identified as S. minuta. This confirms that there are at least two distinct lineages of S. minuta‐like cells, and we describe KM041 as a new species, Stephanopogon pattersoni n. sp. The ultrastructure of KM041 resembles that of previously studied Stephanopogon species, though it has a novel paraxonemal structure in a few cilia. We note that a sub‐basal‐body pad and bulbous axosome are unlikely to be apomorphies for the Stephanopogon–Percolomonas clade.     

Morphological and Molecular Characterisation of Notosolenus urceolatus Larsen and Patterson 1990, a Member of an Understudied Deep‐branching Euglenid Group (Petalomonads)

Petalomonads are particularly important for understanding the early evolution of euglenids, but are arguably the least studied major group within this taxon. We have established a culture of the biflagellate petalomonad Notosolenus urceolatus, and conducted electron microscopy observations and molecular phylogenetic analysis. Notosolenus urceolatus has eight pellicular strips bordered by grooves and underlain by close‐set microtubules. There are ventral and dorsal Golgi bodies. Mitochondria apparently contain fibrous inclusions, as in Petalomonas cantuscygni. A previously undocumented type of large, globular extrusome is present instead of the tubular extrusomes characteristic of Euglenozoa. The feeding apparatus lacks rods and vanes, and is partly supported by an “MTR”. The flagella have complex transition zones that are extremely elongated but unswollen. Only the emergent portion of the anterior flagellum has an organised paraxonemal rod, and also has very fine mastigonemes. The basal bodies are offset and lack connecting fibres. 18S rRNA gene phylogenies show that N. urceolatus is closely related to Petalomonas sphagnophila and P. cantuscygni, not Notosolenus ostium, confirming that current generic assignments based on the number of emergent flagella are phylogenetically unreliable, and making it difficult to infer whether features shared by N. urceolatus and P. cantuscygni (for example) are general for petalomonads.     

不同土壤培肥措施对华北高产农田原生动物丰度的影响

为了解华北高产农田生态系统中秸秆还田、有机肥和化肥投入水平等土壤培肥措施对原生动物群落丰度的影响,1999年10月~2000年9月在山东桓台冬小麦套种夏玉米的田间试验中进行了取样分析。田间处理1~处理9,依序为:全还,麦还,全还 化肥1,麦还 化肥1,全还 化肥2,麦还 化肥2,全还 化肥3,麦还 化肥3和全还 化肥1 有机肥处理。应用3级10倍环式稀释培养法对土壤中鞭毛虫、纤毛虫、肉足虫3类群原生动物的丰度进行了测定。结果显示:该研究地块肥力状况良好;土壤鞭毛虫和肉足虫占有绝大比例,分别为总丰度的39.47%和59.22%,纤毛虫仅占1.31%;土壤原生动物丰度在不同培肥处理中表现出相似的季节性动态变化特征;比较不同土壤培肥措施条件下的原生动物丰度水平为:全还>麦还,全还 化肥1 有机肥>麦还 化肥1,麦还 化肥2,麦还 化肥3>全还 化肥1,全还 化肥2,全还 化肥3;化肥对原生动物丰度表现出明显的抑制作用,而有机肥对原生动力丰度表现出明显的促进作用。化肥的施用量水平对土壤原生动物丰度的影响无显著性差异,作物秸秆采取何种还田方式对土壤原生动物丰度的影响也是不显著的,如麦还 化肥培肥地块的原生动物丰度仅略高于全还 化肥。     

三峡水库运行期间原生动物群落的时空异质性

于2010年10月—2011年6月三峡水库正常运行周期内对库区干流原生动物进行调查,研究其空间分布及水库周期排蓄期间的变化。共检测到原生动物99种,蓄水后纤毛虫有增多的趋势。水库运行的不同阶段优势种不同,大致演变为:砂壳纤毛虫(蓄水期)—非砂壳类纤毛虫(高位运行期间)—有壳肉足虫(低位运行期间)。不同水域优势种也存在差异,从上游到下游特征指示种变化为:有壳肉足虫(变动回水区)—纤毛虫(湖泊区)。结果表明,三峡水库原生动物的分布具有明显的时空异质性(P0.05),影响原生动物时空分布的主要因素有透明度、温度、电导率和叶绿素a。原生动物平均密度为952.19个/L,平均生物量为8.14μg/L。蓄水期上游现存量高于下游,低位运行期间则低于下游。原生动物Marglef和Shannonn-Weiver多样性指数平均值分别为3.78和2.18,1月份最低,6月份最高。蓄水175 m后上游变动回水区原生动物具有较高的丰度。水库冬蓄夏排的运行模式模糊了河流本身的季节变化,使原生动物的种类和现存量更多的受水库水动力学的影响,使水体理化因子和水文特征呈现明显的时空差异,最终形成原生动物种群的时空异质性分布。     

从时空异质性看东湖富营养化中原生动物的演替

1993-08～1994-08,东湖原生动物年均丰度为59,391ind./L,年均生物量为1.40mg/L。从V站到0站,随着营养水平(TSI)增加,数量(A)和生物量(B)显著增加LnA=-58.323+16.503LnTSI(n=5,r=0.983,p=0.003);LnB=-16.840+0.256TSI(n=5,r=0.996,p<0.001),两者均表现出明显的空间异质性。同时,丰度的周年动态模式也发生了明显演替,原来的春季和秋季高峰演变为冬季高峰,营养水平越高,冬季高峰越明显,随营养水平增加形成的原生动物群落结构-种类组成和现存量-的空间格局与年代变化趋势一致。     

Purification and Characterization of Phospholipase C Preferentially Hydrolysing Phosphatidylcholine in Tetrahymena Membranes

A phospholipase C (PLC) activity that preferentially hydrolyses phosphatidylcholine to diacylglycerol and phosphorylcholine was found to be present in Tetrahymena pyriformis, strain W and most of its activity was recovered in the membrane fraction. This enzyme was extracted with 1% Triton X-100 from the membrane fraction and purified to apparent homogeneity by sequential chromatographies on Fast Q-Sepharose, hydroxyapatite HCA-100S, Mono Q and Superose 12 gel filtration columns. The purified enzyme had specific activity of 2083 nmol of diacylglycerol released/mg of protein/min for dipalmitoylphosphatidylcholine hydrolysis. Its apparent molecular mass was 128 kDa as determined by SDS-polyacrylamide gel electrophoresis and was 127 kDa by gel filtration chromatography, indicating that the enzyme is present in a monomeric form. The enzyme exhibited an optimum pH 7.0 and the apparent K_m value was determined to be 166 μM for dipalmitoylphosphatidylcholine. A marked increase was observed in phosphatidylcholine hydrolytic activity in the presence of 0.05% (1.2 mM) deoxycholate. Ca²⁺ but not Mg²⁺ enhanced the activity at a concentration of 2 mM. This purified phospholipase C exhibited a preferential hydrolytic activity for phosphatidylcholine but much less activity was observed for phosphatidylinositol (～ 9%) and phosphatidylethanolamine (～ 2%).     

Insights into discriminating water quality status using new biodiversity measures based on a trait hierarchy of body-size units

Biofilm-dwelling protozoa have successfully used as a feasible bioindicator for bioassessment of water quality status in marine ecosystems. Based on a dataset of biofilm-dwelling protozoa in coastal waters of the Yellow Sea, we demonstrated a spatial variation in body-size spectrum of protozoan communities along a gradient of increasing environmental pollution. Two biodiversity indices, as a new indicator of water quality, were proposed, first being body-size diversity (Δ′) logistically corresponded to taxonomic diversity index but with a trait hierarchy of body-size units based on Euclidean distance resemblance, and the second a modified body-size diversity index (Δ′_m) with a modified hierarchy based on the trait matrix. The values of both indices Δ′ and Δ′_m were found to be significantly correlated with the changes of environmental variables, especially the nutrients. Furthermore, the body-size diversity (Δ′_mrk) at body-size-rank-1 (“genus-level”) resolution might be used as a potential surrogate of those at “species-level” resolution. Thus, we suggest that the ecological parameters based on body-size spectrum may be used as potential bioindicator of water quality status, and that the body-size rank sufficiency might be an effective time-efficient protocol for monitoring programs by identifying taxa to “genus-level” body-size rank.