Integrated analyses of chromosome, molecular and morphological variability in the Andean mice Eligmodontia puerulus and E. moreni (Rodentia, Cricetidae, Sigmodontinae)

Patterns of evolution and systematics of sigmodontine rodents are matters of continuous revision and debate. The silky mouse, Eligmodontia, is a phyllotine rodent adapted to arid environments. Chromosomal and molecular data have identified six species in this genus. Among these E. puerulus and E. moreni are sister taxa from the high Andean and lowland deserts, respectively, with large chromosomal differences and intermediate levels of molecular divergence. The purpose of our study was to quantify the degree of variability (morphological, cytogenetic, and molecular) and to analyze its evolutionary implications within, and between, these sister species in the Monte and Puna biomes of Argentina. Our results show a high variability at the chromosomal and molecular level, but low morphological differentiation among populations of E. puerulus. Diploid numbers vary from 31 to 37 due to a complex Robertsonian system, whereas cytochrome-b distances range from 0.15% to 5.75%. On the other hand, E. moreni shows high morphological differentiation between populations, but low intraspecific differentiation at the molecular (from 0.73% to 1.4%) and chromosomal level (2n = 52). Comparison of E. puerulus with E. moreni reveals high morphological and chromosomal distinction between them, but absence of molecular differentiation. Our results suggest that: (1) the high genetic variability of E. puerulus could be associated to its geographic distribution in the complex topography of the high Andean Puna; (2) the high morphological differentiation between E. moreni and E. puerulus could be the result of natural selection; and (3) molecular polyphyly between E. puerulus and E. moreni could be due to introgression or a recent split of these taxa. Finally, our results emphasize the need to integrate different datasets in the analysis of species variability and diversification, as tools for understanding their evolutionary histories.     

Complete mitochondrial genome of Membranipora grandicella (Bryozoa: Cheilostomatida) determined with next-generation sequencing: The first representative of the suborder Malacostegina

Next-generation sequencing (NGS) has proven a valuable platform for fast and easy obtaining of large numbers of sequences at relatively low cost. In this study we use shot-gun sequencing method on Illumina HiSeq 2000, to obtain enough sequences for the assembly of the bryozoan Membranipora grandicella (Bryozoa: Cheilostomatida) mitochondrial genome, which is the first representative of the suborder Malacostegina. The complete mitochondrial genome is 15,861 bp in length, which is relatively larger than other studied bryozoans. The mitochondrial genome contains 13 protein-coding genes, 2 ribosomal RNAs and 20 transfer RNAs. To investigate the phylogenetic position and the inner relationships of the phylum Bryozoa, phylogenetic trees were constructed with amino acid sequences of 11 PCGs from 30 metazoans. Two superclades of protostomes, namely Lophotrochozoa and Ecdysozoa, are recovered as monophyletic with strong support in both ML and Bayesian analyses. Somewhat to surprise, Bryozoa appears as the sister group of Chaetognatha with moderate or high support. The relationship among five bryozoans is Tubulipora flabellaris + (M. grandicella + (Flustrellidra hispida + (Bugula neritina + Watersipora subtorquata))), which supports for the view that Cheilostomatida is not a natural, monophyletic clade. NGS proved to be a quick and easy method for sequencing a complete mitochondrial genome.     

Barcoding forest insect pests in South Korea: Constructing a basic endemic species dataset

A total of 103 barcode (mitochondrial COI) sequences were newly provided for 77 forest insect pests from 66 genera belonging to Coleoptera, Hemiptera, and Lepidoptera. All 77 species had distinct COI sequences, revealing low intraspecific genetic divergence (< 1.20%) and high interspecific genetic divergence (> 7.30%). Among the 66 genera, 32 COI sequences of 25 species belonging to 16 genera were compared with 280 COI sequences of 117 species belonging to the same 16 genera archived in GenBank, showing that most species were clearly distinguished by barcode sequences. Based on these results, we conclude that a DNA barcode is effective for identifying forest insect pest species.     

Phylogeny,biogeography, and electric signal evolution of Neotropical knifefishes of the genus Gymnotus (Osteichthyes: Gymnotidae)

The Neotropical knifefish genus Gymnotus is the most broadly distributed and the most diverse (34 + species) gymnotiform genus. Its wide range includes both Central and South American drainages, including the Amazon, Orinoco, and La Plata Basins. Like all gymnotiforms, Gymnotus species produce weak electric fields for both navigation and communication, and these fields exhibit interspecific variation in electric waveform characteristics. Both biogeography and electric signal evolution can profitably be analyzed in a phylogenetic context. Here, we present a total evidence phylogeny for 19 Gymnotus species based on data from the mitochondrial cytochrome b and 16S genes (1558 bp), the nuclear RAG2 gene (1223 bp), and 113 morphological characters. Our phylogenetic hypothesis resolves five distinct Gymnotus lineages. In a previous morphology-based analysis, the Central American Gymnotus cylindricus lineage was hypothesized as the sister group to all other Gymnotus species. In our analysis, the G. cylindricus lineage is nested within South American species, and molecular age estimates support a relatively recent origin for the clade in Central America. Phylogenetic optimization of electric signal waveforms indicate that the ancestral state in Gymnotus is a multiphasic (4 + phases of alternating polarity) condition, and independent phase loss has occurred in multiple lineages. Gymnotus is a model group for understanding Neotropical diversification and the evolution of communication at a continental scale.     

Rumen ciliates of domestic cattle (Bos taurus taurus) in Kastamonu,Turkey, with the description of a new species

Species composition and distribution of ciliates were investigated in the rumen contents of 25 domestic cattle (Bos taurus taurus L.) living in Kastamonu, Turkey. Forty-seven species and 37 morphotypes representing 15 genera were identified. Of them, a new species of Ostracodinium was recognized and described as Ostracodinium anatolicum n. sp. This new species has two caudal lobes. The dorsal lobe is small and rounded and the ventral lobe is triangular shaped and bent toward the dorsal side like a thick hook. Furthermore, the anterior end of the macronucleus (1/5 of the length) is bent toward the left like a hook. The density of rumen ciliates in cattle was 96.8 ± 43.3 × 10⁴ cells mL⁻¹ and the mean number of ciliate species per host was 14.2 ± 4.4. Entodinium longinucleatum, E. nanellum, E. simulans and Isotricha prostoma were the most abundant species, each with a prevalence of 88%. Entodinium chatterjeei, E. bifidum m. monospinosum, Hsiungia triciliata, Oligoisotricha bubali, Ostracodinium dogieli, O. mammosum and O. munham are new host records for cattle from Turkey.     

Description of complete mitochondrial genome of the black-veined white,Aporia crataegi (Lepidoptera: Papilionoidea), and comparison to papilionoid species

The black-veined white, Aporia crataegi (Lepidoptera: Papilionoidea) is nearly extinct in South Korea, although substantial numbers of dried specimens are available. One of the common practices used to rescue such endangered species is to launch a re-introduction program after a proper amount of genetic information is analyzed from donor and donee populations. In this study, we sequenced the complete mitochondrial genome (mitogenome) of A. crataegi to accumulate genetic information for subsequent population studies and to further understand the mitogenome evolution in true butterflies, Papilionoidea. The 15,140-bp long A. crataegi mitogenome has typical sets of 37 genes and is the smallest among the true butterfly species, with overall slightly smaller size genes and regions throughout the genome. The A/T content of the genome (81.3%) is the highest in Pieridae, where A. crataegi belongs, but lower than that of the lycaenid species (81.7%–82.7%). Unlike the diversified or modified usage of an anticodon for tRNA^Ser(AGN), the species of Pieridae including A. crataegi all contain GCT that has been hypothesized as being ancestral for Lepidoptera. A total of 111 bp of non-coding sequences are interspersed in 13 regions, ranging in size from 1–49 bp. Among these sequences, relatively longer ones (≥ 16 bp) all have relatively higher sequence identity to other regions of the genome, suggesting partial duplication of the sequences during A. crataegi evolution.     

The spermatozoon of Mengenilla moldrzyki (Strepsiptera,Mengenillidae): Ultrastructure and phylogenetic considerations

Even though the spermatozoa of several strepsipteran species were described earlier, no data were available for the basal family Mengenillidae. Well-fixed material of the recently described Tunisian species Mengenilla moldrzyki was used for a detailed examination of the sperm ultrastructure. The total length is c. 30 μm. The head region contains a conical acrosome vesicle (0.3-0.35 μm) and an elongated nucleus (7.3 μm) with dense chromatin. Some granular material along with a uniformely dense centriole adjunct and two mitochondrial derivatives are visible at the posterior end of the nucleus. The material of the centriole adjunct does not extend along the flagellum and accessory bodies are absent. The mitochondrial derivatives are elongated structures crossed by a longitudinal crista but lacking parallel transverse cristae and paracrystalline material in the dense matrix. The mitochondrial derivatives gradually reduce their size and end at the most posterior tail region. The flagellar axoneme has a 9 + 9 + 2 pattern and originates beneath the nucleus. In the terminal tail region the axoneme gradually disintegrates. Despite the extreme specialization of the endoparasitc group, strepsipteran spermatozoa are mostly characterized by plesiomorphies. The pattern within the order is largely uniform, but Mengenilla displays several apomorphic features compared to the presumptive strepsipteran groundplan (e.g., absence of crystallizations and cristae in the mitochondrial derivatives). The subdivision of the intertubular material into two compartments with a dense beak-like structure adhering to the tubular wall supports a clade Coleopterida (=Strepsiptera + Coleoptera) + Neuropterida.     

Biogeographic origin and radiation of Cuban Eleutherodactylus frogs of the auriculatus species group,inferred from mitochondrial and nuclear gene sequences

We studied phylogenetic relationships of the Eleutherodactylus auriculatus species group to infer colonization and diversification patterns in this endemic radiation of terrestrial frogs of the genus Eleutherodactylus in the largest of the Greater Antilles, Cuba. An initial screening of genetic diversity based on partial sequences of the 16S rRNA gene in almost 100 individuals of all species of the group and covering the complete known geographic range of their occurrence found most species endemic to small ranges in the eastern Cuban mountains while a single species was widespread over most of Cuba. Our molecular phylogeny, based on 3731 bp of four mitochondrial and one nuclear gene, suggests that most cladogenetic events within the group occurred among clades restricted to the eastern mountains, which acted as refugia and facilitated the diversification in this group. Our results reveal two separate colonization events of Central and Western Cuba and allow inferring the timing of the subsequent diversification events that occurred between 11 and 2 Mya. Because populations previously assigned to E. auriculatus represent four genetically strongly divergent lineages that also differ in their advertisement calls, we propose that E. auriculatus as currently recognized comprises four species. The difficulties in assigning the name auriculatus to any of these four species, and the fact that E. principalis is nested within one of them, stress the need for a thorough taxonomic revision of this group.     

Systematics and biogeography of the Neotropical genus Mabuya,with special emphasis on the Amazonian skink Mabuya nigropunctata (Reptilia,Scincidae)

Phylogenetic analyses using up to 1532 base pairs (bp) of mitochondrial DNA from 106 specimens of Neotropical Mabuya, including 18 of the 19 recognized South American and Mesoamerican species, indicate that most species of the genus are monophyletic, including M. nigropunctata that had previously been reported to be paraphyletic. The present results shows that this species includes three highly divergent and largely allopatric lineages restricted to occidental, meridional, and oriental Amazonia. Our dataset demonstrates that previous claims regarding the paraphyletic status of M. nigropunctata and the phylogenetic relationships within this species complex based on the analysis of three mitochondrial and four nuclear genes (approx. 5000 bp) were erroneous and resulted from two contaminated cytochrome b sequences.The phylogenetic results indicate that diversification in the Neotropical genus Mabuya started approximately in the Middle Miocene (15.5–13.4 Ma). The divergence dates estimated for the Mabuya nigropunctata species complex suggest that the major cladogenetic events that produced the three main groups (occidental (oriental + meridional)) occurred during the Late Miocene. These estimations show that diversification within the M. nigropunctata species complex was not triggered by the climatic changes that occurred during the Pleistocene, as has been suggested by several authors. Rather, our data support the hypothesis that the late tertiary (essentially Miocene epoch) was a period that played a very important role in the generation of biological diversity in the Amazonian forests.Speciation between Mabuya carvalhoi, endemic to the coastal mountain range of Venezuela, and M. croizati, restricted to the Guiana Shield, occurred during the Middle Miocene and may have been as the result of a vicariant event produced by the formation of the present day Orinoco river drainage basin and the consequent appearance of the Llanos del Orinoco, which acted as a barrier to dispersal between these two species. The split between M. bistriata and M. altamazonica and between the occidental and (meridional + oriental) clades of M. nigropunctata fits very well with the biogeographic split between the eastern and western Amazon basins reported for several other taxa.     

Recurrent vernal presence of the toxic Alexandrium tamarense/Alexandrium fundyense (Dinoflagellata) species complex in Narragansett Bay,USA

The vernal occurrence of toxic dinoflagellates in the Alexandrium tamarense/Alexandrium fundyense species complex in an enclosed embayment of Narragansett Bay (Wickford Cove, Rhode Island) was documented during 2005 and 2009–2012. This is the first report of regular appearance of the Alexandrium fundyense/Alexandrium tamarense species complex in Narragansett Bay. Thecal plate analysis of clonal isolates using SEM revealed cells morphologically consistent with both Alexandrium tamarense Lebour (Balech) and Alexandrium fundyense Balech. Additionally, molecular analyses confirmed that the partial sequences for 18S through the D1–D2 region of 28S were consistent with the identity of the two Alexandrium species. Toxin analyses revealed the presence of a suite of toxins (C1/2, B1 (GTX-5), STX, GTX-2/3. Neo, and GTX-1/4) in both Alexandrium tamarense (6.31 fmol cell⁻¹ STX equiv.) and Alexandrium fundyense (9.56 fmol cell⁻¹ STX equiv.) isolated from Wickford Cove; the toxicity of a Narragansett Bay Alexandrium peruvianum isolate (1.79 fmol cell⁻¹ STX equiv.) was also determined. Combined Alexandrium tamarense/Alexandrium fundyense abundance in Wickford Cove reached a peak abundance of 1280 cells L⁻¹ (May of 2010), with the combined abundance routinely exceeding levels leading to shellfishing closures in other systems. The toxic Alexandrium tamarense/Alexandrium fundyense species complex appears to be a regular component of the lower Narragansett Bay phytoplankton community, either newly emergent or previously overlooked by extant monitoring programs.     

Peptidomic analysis of skin secretions supports separate species status for the tailed frogs,Ascaphus truei and Ascaphus montanus

The tailed frog Ascaphus truei Stejneger, 1899 is the most primitive extant anuran and the sister taxon to the clade of all other living frogs. The species occupies two disjunct ranges in the Northwest region of North America: the Cascade Mountains and coastal area from British Columbia to Northern California, and an inland range in the northern Rocky Mountains and the Blue and Wallowa mountains. A previous study led to the isolation of eight peptides with antimicrobial activity (termed the ascaphins) from skin secretions of A. truei from the coastal range. The present study has used peptidomic analysis to identify the products of orthologous ascaphin genes in electrically-stimulated skin secretions from inland range specimens. Structural characterization of the peptides demonstrated that ascaphins from the inland range contained the following amino acid substitutions compared with orthologs from the coastal range frogs: ascaphin-1 (Ala¹² → Glu), ascaphin-3 (Asp⁴ → Glu), ascaphin-4 (Ala¹⁹ → Ser), ascaphin-5 (Lys¹² → Thr), and ascaphin-7 (Gly⁸ → Ser and Ser²⁰ → Asn). Orthologs of ascaphins-2, -6, and -8 were not identified but a paralog of ascaphin-5, identical to ascaphin-5 from coastal range frogs, was found. The data support the claims, derived from analysis of the nucleotide sequences of mitochondrial genes, that the inland populations of the tailed frog should be recognized as a distinct species, the Rocky Mountain tailed frog Ascaphus montanus and that the divergence of the species from A. truei probably occurred in the late Miocene (approximately 10 Mya).     

Prediction of Egeria najas and Egeria densa occurrence in a large subtropical reservoir (Itaipu Reservoir,Brazil-Paraguay)

Incidence data of two native submerged aquatic macrophytes (Egeria najas Planch. and Egeria densa Planch.) were obtained in eight arms of a large (1350 km²) subtropical reservoir (Itaipu Binacional Reservoir, Brazil-Paraguay). Environmental variables were measured simultaneously. Two large-scale surveys in the same localities identified by a global positioning system were carried out in April 1999 (n = 235) and January 2001 (n = 230). Logistic regressions were used to test the effect of environmental variables on the likelihood of E. najas and E. densa presence or absence. The two species were found under different environmental conditions: conductivity, light attenuation coefficient (k) and fetch were, in this order, the most important environmental variables in predicting the probability of occurrence of E. najas, whereas light attenuation coefficient was the main predictor of the probability of occurrence of E. densa. Thus, both species were negatively affected by the light attenuation coefficient. However, this effect was stronger in E. densa. The small area occupied by these species may be accounted for by the permanent high turbidity of Itaipu Reservoir. Additionally, the dominance of E. najas over of E. densa can be explained by the probably higher light requirements of E. densa. In other reservoirs worldwide, with higher water transparency, the opposite is frequently true. Between 1999 and 2001, an episodic water-level drawdown (5 m) caused the disappearance of submerged vegetation. After water-level normalization, previous vegetation presence (in 1999) was an important predictor of the probability of occurrence of E. najas in 2001.     

Gastro-intestinal handling of water and solutes in three species of elasmobranch fish,the white-spotted bamboo shark,Chiloscyllium plagiosum,little skate,Leucoraja erinacea and the clear nose skate Raja eglanteria

The present study reports aspects of GI tract physiology in the white-spotted bamboo shark, Chiloscyllium plagiosum, little skate, Leucoraja erinacea and the clear nose skate, Raja eglanteria. Plasma and stomach fluid osmolality and solute values were comparable between species, and stomach pH was low in all species (2.2 to 3.4) suggesting these elasmobranchs may maintain a consistently low stomach pH. Intestinal osmolality, pH and ion values were comparable between species, however, some differences in ion values were observed. In particular Ca²⁺ (19.67 ± 3.65 mM) and Mg²⁺ (43.99 ± 5.11 mM) were high in L. erinacea and Mg²⁺ was high (130.0 ± 39.8 mM) in C. palgiosum which may be an indication of drinking. Furthermore, intestinal fluid HCO₃^? values were low (8.19 ± 2.42 and 8.63 ± 1.48 mM) in both skates but very high in C. plagiosum (73.3 ± 16.3 mM) suggesting ingested seawater may be processed by species-specific mechanisms. Urea values from the intestine to the colon dropped precipitously in all species, with the greatest decrease seen in C. plagiosum (426.0 ± 8.1 to 0 mM). This led to the examination of the molecular expression of both a urea transporter and a Rhesus like ammonia transporter in the intestine, rectal gland and kidney in L. erinacea. Both these transporters were expressed in all tissues; however, expression levels of the Rhesus like ammonia transporter were orders of magnitude higher than the urea transporter in the same tissue. Intestinal flux rates of solutes in L. erinacea were, for the most part, in an inward direction with the notable exception of urea. Colon flux rates of solutes in L. erinacea were all in an outward direction, although absolute rates were considerably lower than the intestine, suggestive of a much tighter epithelia. Results are discussed in the context of the potential role of the GI tract in salt and water, and nitrogen, homeostasis in elasmobranchs.     

Vibrio aestivus sp. nov. and Vibrio quintilis sp. nov., related to Marisflavi and Gazogenes clades,respectively

Two new Vibrio species, Vibrio aestivus and Vibrio quintilis, are described after a polyphasic characterization of strains M22^T, M61 and M62^T, isolated from seawater collected off a beach on the East coast of Spain (Valencia). All three strains are Gram negative, mesophilic, slightly halophilic, fermentative rods. V. aestivus (M22^T = CECT 7558^T = CAIM 1861^T = KCTC 23860^T and M61 = CECT 7559 = CAIM 1862 = KCTC 23861) is oxidase positive, reduces nitrates to nitrites, is negative for Voges Proskauer, arginine dihydrolase and indole and non hydrolytic on most substrates tested. The 16S rRNA gene sequences of M22^T and M61 are most similar to Vibrio marisflavi (97.1–97.2%) but phylogenetic analysis using NJ, MP and ML methods display Vibrio stylophorae (96.2% similarity) as sibling species. The three species form a deep clade in the genus Vibrio. Average Nucleotide Identity (ANI) values, determined as a measure of overall genomic resemblance, confirmed that strains M22^T and M61 are members of the same species, different to V. marisflavi CECT 7928^T.V. quintilis (M62^T = CECT 7734^T = CAIM 1863^T = KCTC 23833^T) is aerogenic, arginine dihydrolase and Voges Proskauer positive, oxidase negative and unable to reduce nitrate, traits shared by most species in the Gazogenes clade. It is unpigmented and does not grow on TCBS Agar. 16S rRNA gene similarities to its nearest species, Vibrio aerogenes and Vibrio mangrovi, are 97.6% and 96.0% respectively. Strain M62^T and V. aerogenes CECT 7868^T display ANI values well below the 95% boundary for genomic species.     

Dispersal pattern of airborne emissions from an aluminium smelter in Ouro Preto,Brazil, as expressed by foliar fluoride accumulation in eight plant species

In order to evaluate the dispersal pattern of airborne fluoride emissions, from a single source in the city of Ouro Preto, Brazil, the fluoride impact on some herbaceous plant species was studied using the plants as passive bioindicators. Foliar fluoride contents of eight species collected at different distances from an aluminium smelter were analyzed. The plant species were: Baccaharis dracunculifolia, Bidens pilosa, Borreria verticillata, Calopogonium mucunoides, Erigeron bonariensis, Hedychium coronarium, Ipomoea purpurea and Ipomoea cairica. In all species the fluoride accumulation decreased exponentially with the distance from the emission source. There was specific and distinct variation in fluoride accumulation among the species, a group of high-accumulator species (B. dracunculifolia and Bidens pilosa) and a group of low-accumulator species (I. cairica, H. coronarium and Borreria verticillata). C. mucunoides and E. bonariensis occupied an intermediate position. There was a pattern of plant contamination response during the periods analyzed. The plants nearest to the emission source, between 0.4 km northwest and 1.1 km east, showed fluoride contamination traits in leaves reaching values between 100 and 500 μg g⁻¹. Moreover, fluoride contents higher than 1000 μg g⁻¹ were found in these plants. At the most distant stations, situated 2.9 km northwest and 6 km east from the factory, the fluoride content of the dry matter was less than 10 μg g⁻¹ showing that plants at those distances were submitted to minimum contamination. There were different patterns of tolerance among the species analyzed. While B. dracunculifolia accumulated fluoride up to 1500 μg g⁻¹ in dry matter without any signs of injury, Borreria verticillata showed severe necrosis in leaves, but the fluoride content found was not higher than 120 μg g⁻¹.     

Immature mosquitoes in agricultural wetlands of the coastal plain of Georgia,U.S.A.: Effects of landscape and environmental habitat characteristics

This study is the first to report on the relationships between immature mosquitoes (larvae and pupae) and landscape and environmental habitat characteristics in wetlands associated with row crop agriculture. Indicator species analysis (ISA) was used to test for associations among mosquito species and groups of wetland sites with similar Landscape Development Intensity (LDI) values. Results indicated that Anopheles quadrimaculatus, Culex erraticus, and Psorophora columbiae were associated with agricultural wetlands (LDI > 2.0), whereas Anopheles crucians and Culex territans were associated with forested reference wetlands (LDI < 2.0) in both wet and dry years. The species fidelity to wetland type, regardless of the hydrologic regime, demonstrates these species are robust indicators of wetland condition. Data on immature mosquito assemblages were compared to selected landscape and environmental habitat variables using Akaike's Information Criterion (AIC_c) model selection. LDI indices, dissolved oxygen concentration, the proportion of emergent vegetation, and the proportion of bare ground in wetlands were important factors associated with the selected mosquito species. These results indicate that LDI indices are useful in predicting the distributions of disease vectors or other nuisance mosquito species across broad geographic areas. Additionally, these results suggest mosquitoes are valuable bioindicators of wetland condition that reflect land use and hydrologic variability.     

Chloroplast DNA variation and phylogeographic patterns in the Chinese endemic marsh herb Sagittaria potamogetifolia

We examined chloroplast DNA (cpDNA) atpB–rbcL intergenic spacer sequences variation within Sagittaria potamogetifolia, an endangered and endemic marsh herb in China. Sequence data were obtained from 54 individuals in six extant populations of the species. Sequences appeared to evolve neutral (Tajima's criterion D = −1.59826, 0.1 > P > 0.05 and Fu and Li's tests D* = −1.44484, P > 0.1; F* = −1.83446, P > 0.1). Eleven haplotypes were identified in S. potamogetifolia. A relatively high level of haplotype diversity (h = 0.0.699) and low level of nucleotide diversity (pi = 0.0035 ± 0.0020) were detected in S. potamogetifolia. Pairwise comparisons of F_st and Nm deduced from cpDNA variation suggested no significant genetic differentiation between populations of S. potamogetifolia excepted for the WY-1 population. Low genetic differentiation among populations and also among regions was consistently indicated by both hierarchical analyses of molecular variance (AMOVA) and the structure of a neighbor-joining tree. Lack of population differentiation between populations or between regions in cpDNA sequences may be due to effects of lower substitution rates or lineage sorting. In the minimum spanning network, all tip haplotypes except for the haplotype J were unique to a particular population, while the interior nodes except for the haplotype E were widespread (haplotype A). From nested clade analysis (NCA), the evolutionary events such as restricted gene flow with isolation by distance and allopatric fragmentation were inferred to responsible for the current distribution of S. potamogetifolia populations, as well as their genetic diversity.     

Complete mitochondrial genome of Coelomactra antiquata (Mollusca: Bivalvia): The first representative from the family Mactridae with novel gene order and unusual tandem repeats

The complete mitochondrial genome plays an important role in the accurate inference of phylogenetic relationships among metazoans. Mactridae, also known as trough shells or duck clams, is an important family of marine bivalve clams in the order Veneroida. Here we present the complete mitochondrial genome sequence of the Xishishe Coelomactra antiquata (Mollusca: Bivalvia), which is the first representative from the family Mactridae. The mitochondrial genome of C. antiquata is of 17,384 bp in length, and encodes 35 genes, including 12 protein-coding, 21 transfer RNA, and 2 ribosomal RNA genes. Compared with the typical gene content of animal mitochondrial genomes, atp8 and tRNAS₂ are missing. Gene order of the mitochondrial genome of C. antiquata is unique compared with others from Veneroida. In the mitochondrial genome of the C. antiquata, a total of 2189 bp of non-coding nucleotides are scattered among 26 non-coding regions. The largest non-coding region contains one section of tandem repeats (99 bp × 11), which is the second largest tandem repeats found in the mitochondrial genomes from Veneroida. The phylogenetic trees based on mitochondrial genomes support the monophyly of Veneridae and Lucinidae, and the relationship at the family level: ((Veneridae + Mactridae) + (Cardiidae + Solecurtidae)) + Lucinidae. The phylogenetic result is consistent with the morphological classification. Meanwhile, bootstrap values are very high (BP = 94–100), suggesting that the evolutionary relationship based on mitochondrial genomes is very reliable.     

Unusual hepatic mitochondrial arginase in an Indian air-breathing teleost,Heteropneustes fossilis: Purification and characterization

A functional urea cycle with both cytosolic (ARG I) and mitochondrial (ARG II) arginase activity is present in the liver of an ureogenic air-breathing teleost, Heteropneustes fossilis. Antibodies against mammalian ARG II showed no cross-reactivity with the H. fossilis ARG II. ARG II was purified to homogeneity from H. fossilis liver. Purified ARG II showed a native molecular mass of 96 kDa. SDS–PAGE showed a major band at 48 kDa. The native enzyme, therefore, appears to be a homodimer. The pI value of the enzyme was 7.5. The purified enzyme showed maximum activity at pH 10.5 and 55 °C. The K_m of purified ARG II for l-arginine was 5.25 ± 1.12 mM. l-Ornithine and N^ω-hydroxy-l-arginine showed mixed inhibition with K_i values 2.16 ± 0.08 and 0.02 ± 0.004 mM respectively. Mn^+ 2 and Co^+ 2 were effective activators of arginase activity. Antibody raised against purified H. fossilis ARG II did not cross-react with fish ARG I, and mammalian ARG I and ARG II. Western blot with the antibodies against purified H. fossilis hepatic ARG II showed cross reactivity with a 96 kDa band on native PAGE and a 48 kDa band on SDS–PAGE. The molecular, immunological and kinetic properties suggest uniqueness of the hepatic mitochondrial ARG II in H. fossilis.