Lineaperpetua gen.nov.:a new diatom genus in the Thalassiosirales supported by morphology and molecular data

Based on a combination of morphology and molecular data of ribosomal DNA genes,a new diatom genus Lineaperpetua gen.nov.Yu,You,Kociolek&Wang is described.The features that help define Lineaperpetua at the level of genus include:a tangentially undulated valve face;continuous cribra areolae on the valve interior consisting of pores arranged as strips;single rimoportula located inside the ring of marginal fultoportulae.Additionally,phylogenetic analysis based on nuclear small subunit(SSU)rDNA sequences and nuclear large subunit(LSU)rDNA gene placed the three strains of L.lacustris in a single,monophyletic clade at a considerable sequence distance from the other genera(Thalassiosira,Conticribra,Planktoniella,Shinodiscus,and other genera)belonging to Thalassiosirales.Despite the similarities with some species of Thalassiosira,Conticribra,and Spicaticribra,the suite of features found in Lineaperpetua differentiate it from these other genera.These molecular data and morphological characters suggest an affinity of the new genus to the Thalassiosiraceae.

Morphological comparison and molecular marker screening of three Skeletonema species found in Changjiang(Yangtze)River Basin

In our recent investigations of diatom diversity,we studied three species,namely,Skeletonema costatum,Skeletonema subsalsum,and Skeletonema potamos.Although they have been found frequently in Changjiang(Yangtze)River Basin,their morphological and molecular identification is difficult in taxonomy.Therefore,to integrate morphological and molecular biological approaches,we compared systematically their morphological characters and performed phylogenetic analysis.Twelve strains of Skeletonema were collected and isolated from Shanghai and Jiangsu,China,and their morphological characteristics were examined by light microscopy(LM)and the scanning electron microscopy(SEM).Based on morphological comparison,we determined that S.potamos is easy to distinguish from the other two species.The heavily silicified areolae,undulated or cleft distal ends of terminal fultoportula processes(TFPPs),absence of basal pores of fultoportula processes(FPPs),the rootlike protrusions of FPPs,and no interlocking connection are the stable characteristics that can be used to identify S.potamos.However,there are only two features that can distinguish S.costatum from S.subsalsum,namely the location of terminal rimoportulae(TRPs)and the distal shape of TFPPs.In addition,we amplified and sequenced nine common genetic markers from the strains,from which 101 sequences were obtained,constructed phylogenetic trees based on the nine genes and evaluated that seven genes can be used to identify S.potamos,and revealed that S.subsalsum is the closest known relative of S.costatum,and only ATP synthetase beta-subunit gene(atp B)is able to distinguish them from each other,which strongly support that it is an effective molecular marker for Skeletonema.This work provided a theoretical basis for the taxonomic study of Skeletonema.

Qinia gen.nov.(Bacillariophyceae:Cymbellales)from Yunnan Province,China

An interesting group of cymbelloid diatoms was collected from lakes in Yunnan Province,China,and observations on their valve morphology made using light and scanning electron microscopy.These cymbelloid species all have apical pore fields,slit-like areolae,and areolar occlusions,and they all lack of stigmata.In this paper we propose the new genus Qinia gen.nov.for these taxa and describe them as new:Q.lashii sp.nov.,Q.aequalis sp.nov.,and Q.daliensis sp.nov.The genus Qinia gen.nov.has lanceolate valves asymmetrical about their apical axes,raphe located in the middle of valve,distal raphe ends bent to the dorsal margin that bisects the apical pore fields(APFs),no stigmata,areolae with slit-like external openings and projections occluding the areolar openings internally.This genus resembles the genus Cymbella in the presence of APFs,but differs from Cymbella by a lack of stigmata,and by having external distal raphe ends that bisect the apical pore fields.Like Reimeria,the external distal raphe ends bisect the lobes of the APF,but Qinia species differ from Reimeria in that they have no stigmata and the distal raphe ends are deflected dorsally,not ventrally.Comparisons were made between Qinia and other cymbelloid genera whose members possess apical pore fields.Features that distinguish each species of the new genus are also discussed.

Morphological and phylogenetic analysis of a new Melosira species and revision of freshwater Melosira in China

Melosira is one of the most common diatom genera found in freshwater ecosystems.There are many freshwater species of Melosira,of which M.varians is the most common.In our investigation of periphytic diatoms in the Jinsha River,China,a new species,M.capsularum sp.nov,was characterized in combined morphological and molecular approaches.M.varians was also analyzed using molecular data.The new species is similar to M.varians,M.moniliformis,M.nummuloides,and M.lineata in morphology.The cells are capsular and join to filaments by mucilage pads that are secreted on the valve face and united into pairs by their cingula.The valve face is domed and covered with small granules,and the valve mantle edge has a milled appearance.The two strains of M.capsularum are in a single clade obviously away from other Melosira species,as determined in phylogenetic analysis based on nuclear small subunit(SSU)rDNA sequences and the chloroplast-encoded rbc L gene.Thus,the results of morphological comparisons and phylogenetic analysis based on molecular data provide strong evidence that M.capsularum is a new species,thereby increasing the total number of recognized freshwater diatom species in China.In addition,we have systematically reclassified the freshwater Melosira that have been recorded in China.

A case study on Landscape Component Niche based on Landscape Pattern Indices: Yanchi,Ningxia Province, China

Yanchi County is located in the agro-pastoral ecotone and belongs to the ecologically fragile area of Northwest China.It is important to study the evolution of landscape pattern to curb its environmental degradation.In order to intuitively show how the landscape pattern of the study area changes over time,Landsat Thematic Mappers(TM)and Landsat Operational Land Imager(OLI)data of 1991,2000,2010 and 2017 were used.This paper attempts to apply niche theories and methods into landscape ecology,and constructs a niche model of landscape components by using"n-dimentional hypervolume niche theory"and landscape pattern indices.By evaluating the spatial and temporal evolution of niche from the perspective of two-dimensional space to reflect the changes of landscape pattern in the study area over the past 26 years,new theories and methods were introduced for the characterization of landscape pattern.The results indicate that:1)The larger the attribute and dominance value of landscape components,the higher the ecological niche and the stronger the control effect on the overall landscape.2)The ecological niche of each landscape component was significantly different,just as its control effect on the overall landscape.3)The dynamic change of the ecological niche of each landscape component was different,with grassland,unused land and arable land always in a high dominant position,although the ecological niche of construction land and water area was always low.In general,the introduction of niche theory into the landscape ecology provided a new method to study the changes in regional landscape pattern.

Inhibitive effect on apoptosis in splenic lymphocytes of mice pretreated with Lingzhi (GanodermaLucidum) spores

OBJECTIVE： To investigate how the pretreatment of mice with Ganoderma spores affected the apop- tosis of their splenic lymphocytes induced by dexa- methasone after 19 days treatment. METHODS： Sixty Kunming mice were randomly di- vided into six groups： blank control groupdrenched with normal saline; a drug control group drenched with 150 mg/mL Ganoderma spores; a model group treated with saline; a low dose group with S0 mg/mL Ganoderma spores; a moderate dose group with 100 mg/mL Ganoderma spores; and a high dose group with 150 mg/mL Ganoderma spores. The effect of Ganoderma spores on apoptosis in spleen lymphocytes was analyzed. All groups were treated for 19 days. On day 20, the model group and the 3 treatment groups were intraperitoneally injected dexamethasone to induce apoptosis. Splenic index and apoptosis indes were employed to measure cell apoptosis RESULTS： The results showed that Ganoderma spores reduced the splenic index to different de- grees in each group and the best effect was seen in the high dose group （P〈0.05）. Terminal dexynucleo- tidyl transferase （TdT）-mediated 2＇-Deoxyuridine 5＇-Triphosphate nick end labeling staining revealed that the apoptotic index in all groups administered Ganoderma spores differed significantly from the model group, and a dose-response was observed. Flow cytometric analysis indicated that spleen lym- phocyte apoptosis in the model group was exten- sive. Each dose of Ganoderma spores inhibited dexamethasone-induced apoptosis in spleen lym- phocytes, and a dose-response was observed as well. The highest dose of Ganoderma spores de- creased Malondialdehyde content in serum in- duced by dexamethasone （P〈0.05）. CONCLUSION： The findings imply that the pretreat- ment of the mice with Ganoderma spores could re- duce the apoptosis rate induced by dexametha- sone in their splenic lymphocytes.

Detection and Characterization of a Novel Norovirus in Bats,China

Dear Editor,Noroviruses(No Vs)are second only to the rotaviruses as etiologic agents of acute fulminant gastroenteritis in infants and young children worldwide,with an estimated 200,000deaths per year in children younger than 5 years of age in developing countries(Patel et al.2008).No Vs are classified within the genus Norovirus of the family Caliciviridae with Norwalk virus as its prototype member(ICTV 2017).The virions are small(38–40 nm in diameter)nonenveloped,with an icosahedral capsidanda linear,positive-

Deletion of an electron donor-binding subunit of the NDH-1 complex, NdhS, results in a heat-sensitive growth phenotype in Synechocystis sp. PCC 6803

In cyanobacteria and higher plants, NdhS is suggested to be an electron donor-binding subunit of NADPH dehydrogenase(NDH-1) complexes and its absence impairs NDH-1-dependent cyclic electron transport around photosystem I(NDH-CET). Despite significant advances in the study of NdhS during recent years, its functional role in resisting heat stress is poorly understood.Here, our results revealed that the absence of NdhS resulted in a serious heat-sensitive growth phenotype in the unicellular cyanobacterium Synechocystis sp. strain PCC6803. Furthermore, the rapid and significant increase in NDH-CET caused by heat treatment was completely abolished, and the repair of photosystem II under heat stress conditions was greatly impaired when compared to that of other photosynthetic apparatus in the thylakoid membrane. We therefore conclude that NdhS plays an important role in resistance to heat stress, possibly by stabilizing the electron input module of cyanobacterial NDH-1 complexes.