Classical and molecular cytogenetics of Atherinella brasiliensis (Teleostei, Atheriniformes) from South coast of Brazil

Cytogenetic studies were performed on specimens of Atherinella brasiliensis from Laranjeiras Bay (Paraná State, Brazil). All specimens had a diploid number of 48 chromosomes, with a karyotype constituted by 4m+14sm+18st+12a and fundamental number of 84. The C-positive heterochromatin was distributed over the nucleolar organizer regions (NORs) in the centromeric regions and on short arms of metacentric and submetacentric chromosomes. Most of this heterochromatin was AT-rich, except in the NORs, which were rich in GC, as detected by double staining with chromomycin A₃/4'-6-diamin-2-phenylindole. Single NORs were located at terminal positions of a submetacentric pair, as confirmed by fluorescent in situ hybridization with 18S rDNA probes. Both techniques showed a size heteromorphism between the homologous chromosomes. The 5S rDNA clusters were located in terminal positions on two chromosomal pairs and also displayed a size heteromorphism. Despite the conserved diploid number, the data on the karyotype microstructure help characterize the cytogenetic profile of this group.     

A prime inference on genetic diversity (RAPDs) in the marine fish Atherinella brasiliensis (Teleostei,Atherinopsidae) from Southern Brazil

Da Silva Cortinhas, M. C., Glienke, C., Prioli, A. J., Noleto, R. B., Matoso, D. A. and Cestari, M. M. 2010. A prime inference on genetic diversity (RAPDs) in the marine fish Atherinella brasiliensis (Teleostei, Atherinopsidae) from Southern Brazil. —Acta Zoologica (Stockholm) 91 : 242–248 As a result of the importance of Atherinella brasiliensis in estuarine environments, random amplified polymorphic DNA (RAPD) markers were used to verify the genetic diversity in A. brasiliensis from two different places in Paranaguá Bay (Paraná State) and one from the Conceição Lagoon (Santa Catarina State). Cytogenetic data have shown a high karyotypic diversity in some populations, although in others this peculiarity demonstrates rearrangements such as heterochromatinization. In the present study, a low level of genetic structuring between the samples from Conceição Lagoon compared with the others was observed through principal coordinate analysis (PCO), analysis of molecular variance and Mantel test according to 79 RAPD markers. As this specie does not perform horizontal migration and the individuals of Conceição Lagoon are isolated, three hypotheses are proposed to explain the results: (i) similar environments may show homogeneous populations not depending on the geographical distance, (ii) because vicariant events that formed the bays occurred in a recent period, the fragmentation effects over the structuring of the genetic diversity may still be low and not totally detectable by the RAPD technique and (iii) the isolation time or the number of generations may not be enough to promote a possible differentiation and genetic structuring between the specimens of these three places. The specimens of these places present a low level of differentiation and genetic structuring so we can consider them as a unique homogeneous population.     

Morphological and genetic variation in seven species of the endangered Chirostoma "humboldtianum species group" (Atheriniformes: Atherinopsidae)

The Chirostoma "humboldtianum" group includes seven silverside species considered as a monophyletic assemblage because of their high genetic and morphological similarities. The group includes five moderately large species, "peces blancos" (117-300 mm standard length--SL) and two smaller species, "charales" (70-142 mm SL). These species are of great economical, cultural and ichthyological interest for local populations, and their management practices are controversial. We investigated the morphometric, meristic and allozyme variations of the seven species (13 populations) and related the variations with life history, habitat and management procedures. Nineteen morphometric variables, eight meristic variables (by multivariate analysis) and 23 allozyme loci of the seven species and populations of Chirostoma were compared. Principal component analysis (PC) of morphometric and meristic data indicate that both sets of data provided information to differentiate among the seven species. The variables that accounted for most of this differentiation were head length (HL), predorsal 1 length (PIL) and length of pelvic fin base (PfbL). PC and Discriminant Analysis (DA) with morphometric data also suggested the differentiation of populations within C. grandocule (83% correctly classified organisms), whereas PC and DA with meristic data differentiated populations of C. humboldtianum (80% correctly classified organisms). The most important morphometric variables for the differentiation were anal fin height (AfH), length of anal fin base (AfbL) and predorsal 2 length (P2L) and the meristic variables D2fR. PdS and AfR. The genetic variability data indicate changes in values of some of the species in relation to previously reported data. The present populations of C. grandocule show a reduction in He (0.002 vs. 0.009). Other species showed an increase; for instance, C. consocium consocium, C. humboldtianum, C. lucius, C. promelas and C. sphyraena averaged He = 0.069 vs 0.027. theta indicated significant genetic differentiation among the analysed species (0.247, S.D. 0.159) and theta s supported the morphological data that suggest intra-specific differentiation (0.360, S. D. 0.154).     

Structure and Development of the Olfactory Organ in the Garfish Belone belone (L.) (Teleostei,Atheriniformes)

Theisen, B., Breucker, H., Zeiske, E., Melinkat, R. 1980. Structure and development of the olfactory organ in the garfish Belone belone (L.) (Teleostei, Atheriniformes). (Institute of Comparative Anatomy, University of Copenhagen, Denmark; Anatomisches Institut, Universität Hamburg, and Zoologisches Institut und Zoologisches Museum, Universität Hamburg, Federal Republic of Germany.) — Acta zool. (Stockh.) 61(3): 161–170. The structure and development of the olfactory organ in the garfish Belone belone (L.) were studied by light and electron microscopy (SEM and TEM). The olfactory organ has the shape of an open groove with a protruding papilla. In embryos and early juveniles the groove is smooth and is provided with a continuous sensory epithelium. During ontogenesis the papilla develops and the composition of the epithelium is changed as areas of nonsensory epithelium appear and eventually separate the sensory epithelium into islets. In adults the sensory epithelium consists of supporting, basal, and two types of receptor cells, ciliated and microvillous. In juveniles also ciliated nonsensory cells are present. This difference can be correlated with differing locomotory habits of adults and juveniles. The receptor cilia show a 9 + 0 microtubular pattern while the nonsensory cilia have the general 9 + 2 pattern. Deviating dendritic endings were found and are considered an indication of ongoing cell dynamics.     

The northernmost record of Bassanago albescens and comments on the occurrence of Rhynchoconger guppyi (Teleostei: Anguilliformes: Congridae) along the Brazilian coast

The northernmost occurrence of Bassanago albescens in the western Atlantic Ocean (off the coast of Rio de Janeiro, Brazil) is presented and compared with the available data on this species. Specimens formerly identified as Rhynchoconger guppyi from off the southern Brazilian coast are regarded as B. albescens.     

Aminopeptidases function as endocytic receptors in the trophotaenial placenta of the goodeid fish,Ameca splendens (Teleostei: Atheriniformes)

Viviparity in goodeid teleosts is characterized by the elaboration of trophotaeniae, extraembryonic proctodaeal appendages facilitating maternal-embryonic nutrient transfer. The trophotaenial absorptive cells (TACs) express aminopeptidases (APs) such as APA, APN, gamma-glutamyltransferase (gamma-GT), dipeptidyl aminopeptidase (DAP) IV, and neutral endopeptidase (NEP) as inferred from the results of cleavage experiments with, respectively, Glu-alpha-(4M beta NA), Ala-(4M beta NA), Glu-gamma-(4M beta NA), Gly-Pro-(4M beta NA), and Gl-(Ala)(3)-(4M beta NA). Enzyme reaction product was localized to the apical and basolateral plasma membrane as well as to some intracellular compartments. In the accompanying report (Schindler, 2003) evidence is presented that the trophotaeniae of Ameca splendens embryos randomly, yet specifically, bind and ingest proteins as well as certain copolymers of amino acids. Present results demonstrate that endocytosis is significantly inhibitable by unspecific proteinase inhibitors, such as diisopropylphosphorofluoride, phenylmethanesulfonylfluoride, antipain, 1.10-phenanthroline, and dithiothreitol. The specific microbial AP inhibitors amastatin, bestatin, and phosphoramidon suppressed protein binding to TACs more effectively when added in combination than did either agent alone. Moreover, in the presence of 4M beta NA assay substrates of APs the capability of TACs to bind proteins was significantly reduced. Conversely, the rate at which 4M beta NA substrates were cleaved by trophotaenial APs was modified in the presence of proteins. Depending on protein concentrations the AP-catalyzed reactions either decreased or increased in velocity. Analysis of the enzyme kinetics by methods of linear transformation suggests that proteins bind to APs competitively, thereby adopting the role of enzyme inhibitors. On the other hand, protein binding to APs appears to be a signal to translocate enzymes from an internal pool to the surface membrane. In the presence of primaquine, the rate of AP-catalyzed cleavage of 4M beta NA substrates was significantly reduced. That can be put down to the fact that weak bases disrupt the recycling of endocytosed membrane constituents. In conclusion, there is evidence that APs in the trophotaenial placenta of A. splendens function as scavenger receptors mediating in the delivery of embryotrophic proteins for lysosomal degradation.     

Scavenger receptors facilitate protein transport in the trophotaenial placenta of the goodeid fish,Ameca splendens (Teleostei: Atheriniformes)

In the goodeid placental analogue, trophotaeniae provide extraembryonic gut-derived exchange surfaces. Ameca splendens embryos possess endocytosing trophotaeniae that are capable of absorbing a dazzling array of proteinaceous substances. The iron core protein, native ferritin (NF), and several radioiodinated proteinaceous substances were used to study ligand and binding site pathways in the trophotaenial absorptive cells (TACs). Time sequence analysis of NF trafficking indicated an exclusively lysosomal pathway. Binding to TACs of NF was completely inhibitable by proteins containing multiple lysine residues such as apoferritin, bovine serum albumin (BSA), human transferrin (HTf), fetuin, hemoglobin, myoglobin, cytochrome c, ubiquitin, parvalbumin as well as the random copolymers, poly(Glu,Lys,Tyr)6:3:1 and poly(D-Glu,D-Lys)6:4. Peptide hormones and pepsin that contains only one lysine residue did not produce inhibitory effects. Radiolabels such as (125)I-BSA, (125)I-HTf and (125)I-poly(Glu,Lys,Tyr) bound to trophotaeniae in a specific saturable manner. Any two proteins were shown to hinder one another in getting hold of a binding site. Concentration-dependent (125)I-BSA binding and Scatchard analysis of the data revealed both low- and medium-affinity binding with apparent dissociation constants, K(d)s, of 3.4 x 10(-5) M and 2 x 10(-7) M, respectively. Binding of NF and radioiodinated proteins was inhibited in the presence of a large excess of L-Lys, D-Lys, and several dipeptides containing Lys. Both Ca(2+)-depletion and low pH dramatically reduced the TACs' capacity to bind proteins. The effects of acidotropic agents included a reversible loss of surface protein binding sites, tremendous vacuolation, and the arrest of lysosomal degradation. Collectively, present results demonstrate that TACs bind and absorb multiple proteinaceous substances through a mechanism satisfying the criteria of receptor-mediated endocytosis. It is concluded that scavenger protein binding sites are used to ingest proteins for lysosomal degradation, helping to meet the embryos' amino acid requirement.     

Ultrastructure and protein uptake of the embryonic trophotaeniae of four species of goodeid fishes (Teleostei: Atheriniformes)

Embryos of most species within the viviparous teleost family Goodeidae develop characteristics perianal processes that are considered to be derivatives of the embryonic hindgut. These processes, termed trophotaeniae, are covered with an epithelium that is continuous with the absorptive epithelium lining the hindgut. Gestation is intraovarian, and trophotaeniae mediate the uptake of maternally provided nutrients into the embryo from the ovarian fluid. Ultrastructural examination of the trophotaeniae of four goodeid species reveals substantial diversity in the organization of the epithelium within the family. The trophotaeniae of Alloophorus robustus, Zoogoneticus quitzeoensis, and Ilyodon furcidens have morphological features associated with the endocytosis of macromolecules and can be shown to endocytose the exogenous protein tracer horseradish peroxidase (HRP) rapidly. The trophotaenial epithelia of these species differ from one another with respect to other morphological features such as cell height, organization of the brush border, and the complexity of the intercellular spaces. The trophotaeniae of Goodea atripinnis lack an endocytotic apparatus and do not endocytose HRP. However, the overall organization of G. atripinnis trophotaenial cells suggests a function as a transporting epithelium. The cells have a dense brush border, numerous mitochondria, and many mitochondria that are enveloped by lamellar sheets of intracellular membrane. Post-fixation with osmium and potassium ferrocyanide reveals a marked difference in the complexity of the subepithelial connective tissue. Alloophorus robustus and Z. quitzeoensis exhibit an extremely electron-dense ground substance containing many acellular components. Goodea atripinnis exhibits an electron-lucid ground substance with few acellular components. © 1994 Wiley-Liss, Inc.     

Signatures of Directional and Balancing Selection in the Silverside Basilichthys microlepidotus (Teleostei: Atherinopsidae) Inhabiting a Polluted River

Evolutionary Biology - Currently environmental pollution is one of the most important factors affecting natural populations and acting as a strong selective pressure. Therefore, identifying genes...     

Beach dynamics and nest distribution of the leatherback turtle (Dermochelys coriacea) at Grande Riviere Beach, Trinidad & Tobago

Grande Riviere Beach in Trinidad and Tobago is an important nesting site in the Caribbean for the Critically Endangered leatherback sea turtle, Dermochelys coriacea. Community members were concerned that beach erosion and seasonal river flooding were destroying many of the nests deposited annually and thought that a hatchery was a possible solution. Over the 2001 turtle nesting season, the Institute of Marine Affairs (IMA) assessed the spatial and temporal distribution of nests using the Global Positioning System recorded to reference points, and beach dynamics using permanent bench mark profile stations, to determine areas of high risk and more stable areas for nesting. A total of 1449 leatherback nests were positioned. It was evident that at the start of the season in March, the majority of leatherback nests were deposited at the eastern section of the beach. After May, there was a continuing westward shift in nest distribution as the season progressed until August and beach erosion in the eastern section became predominant. The backshore remained relatively stable along the entire beach throughout the nesting season, and erosion was predominant in the foreshore at the eastern section of the beach, from the middle to the end of the season. Similar trends in accretion and erosion were observed in 2000. River flooding did not occur during the study period or in the previous year. With both high risk and more stable regions for turtle nesting available at Grande Riviere Beach, there was no compelling evidence to justify the need for a hatchery.     

Intertidal interstitial Halicyclops from the Brazilian coast (Copepoda: Cyclopoida)

H. tageae sp. n. and Halicyclops ytororoma sp. n. are described from the intertidal interstitial water of Brazilian beaches. H. tageae is distinguished from all congeneric species by the number of setae on legs 1–4 endopodite 2 (1, 1, 2, 2) and by possessing a reduced inner spine on the leg 5 exopodite. It shares with H. brevispinosus, H. pusillus and H. canui the spine formula 2, 3, 3, 3 on exopodite 3 of swimming legs 1–4. H. ytororoma closely resembles H. gauldi and differs from this species by having 4 setae on leg 1 endopodite 3; H. gauldi has 3 setae on this segment.This is the first record of Halicyclops from marine interstitial water in Brazil.     

A new goby, Glossogobius minutus (Teleostei: Gobiidae) from the south-west coast of India

A new species of gobiid fish Glossogobius minutus collected from the south-west coast of India is described. The morphological, morphometric and meristic characters were studied with special emphasis on osteology. The various characters are compared with those of G. giuris (Harn.) and G. biocellatus (Val.), the only other species of the genus reported from this region. Glossogobius minutus is a benthic omnivore and shows distinct sexual dimorphism.     

Breeding tubercles of Phoxinus (Teleostei: Cyprinidae): Morphology,distribution, and phylogenetic implications

Studies of the skin with scanning electron microscopy (SEM) reveal a diverse morphology in breeding tubercles among species of Phoxinus. Based mainly on the fine structure of the surface of tubercles, nine morphotypes, coded as letters A-I, occur in Phoxinus. Most of the morphotypes are common to all Phoxinus species, but type E is present only on the dorsum of the head of P. phoxinus, type H on the breast scale of female P. phoxinus, and type I on the pectoral fin in P. erythrogaster. Multicellular breeding tubercles bearing unicellular projections, identified as unculiferous tubercles are found in type H and probably types F and G. The distribution of tubercles on head, body, and fins is described and compared among Phoxinus species. Breeding tubercles in Phoxinus and other minnow genera are compared in order to interpret the phylogenetic implication of the tuberculation in Phoxinus. The deeply embedded breast scales and the breeding tubercles on their apical margins, and a series of tubercles on the apical margins of lateral scales of the caudal peduncle in breeding males of Phoxinus species, are the characters supporting the monophyly of the genus. © 1996 Wiley-Liss, Inc.     

A new species of Lernanthropus De Blainville, 1822 (Copepoda: Lernanthropidae) parasitic on Menticirrhus ophicephalus (Jenyns) (Teleostei: Sciaenidae) from the Peruvian coast

Lernanthropus huamani n. sp. (Copepoda: Lernanthropidae), a parasite of the Peruvian sciaenid fish Menticirrhus ophicephalus (Jenyns), is described and illustrated. The new species differs from all other species of Lernanthropus by a combination of characters, including the dorsal plate, legs and other appendages. L. guacoldae Villalba & Fernández, 1984 is considered a synonym of L. pacificus Oliva & Duran, 1982.     

Feeding activity of Callinectes ornatus Ordway, 1863 and Callinectes danae Smith, 1869 (Crustacea, Brachyura, Portunidae) in Ubatuba, SP, Brazil

The feeding activity along the day cycle and the time consumed for extracellular digestion were evaluated in the portunids C. ornatus and C. danae. Swimming crabs were obtained from trawling in Ubatuba bay, São Paulo, Brazil, during both the rainy and dry seasons. In each season, daily scheduled samples were taken at dawn (±6 h), noon (±12 h), dusk (±18 h) and midnight (±24 h). All individuals were dissected and the degree of stomach replenishment was recorded. In order to estimate the time elapsed for extracellular digestion, crabs were fed, and groups were dissected at 30 min intervals to check the conditions of their stomachs. In general, both species show a higher feeding activity during periods of lower light intensity, as evidenced by an increased percentage of full stomachs in dusk and midnight samples. The obtained results support higher feeding activity at night in these species and indicate short time for extracellular digestion, not exceeding 8 h. Nevertheless, full stomachs were recorded in all sampling schedules. In this case, it should be considered that elimination of certain food items such as fish bones, mollusk shells and carapace fragments of crustaceans could take more time than other items. Additionally, some crab species could require a cycle of cell replacement in the midgut gland epithelium until they can take their next meal.     

Biological activity in extracts of ascidians (Tunicata, Ascidiacea) from the northeastern Brazilian coast

Ascidians are marine animals with a great ability to synthesize bioactive substances. This study examined the cytotoxic potential of 10 ascidians found in the coastal waters of Northeast Brazil. Samples of the species Eudistoma vannamei Millar, 1977, Eudistoma sp., Didemnum ligulum Monniot F., 1983, Didemnum psammatodes (Sluiter, 1895), Didemnum sp., Polysyncraton sp., Trididemnum sp., Cystodytes dellechiajei (Della Valle, 1877), Euherdmania sp., and an unidentified species belonging to the Holozoidae family were extracted in methanol 5:1 (v/w). The extracts were tested for cytotoxicity using the brine shrimp lethality assay, sea urchin egg development assay, hemolysis assay, and MTT assay using tumor cell lines. The extract of E. vannamei showed the highest toxicity in brine shrimp (LD₅₀=34.7 μg/ml) and in all tumor cell lines tested, with an IC₅₀ of <2 μg/ml for CEM, 11.2 μg/ml for HL-60, 23.8 μg/ml for B16, and 14.3 μg/ml for HCT-8. In sea urchin eggs, it inhibited the cell cycle progression mainly at the blastula stage (IC₅₀=74.8 μg/ml). The extract of Euherdmania sp. also exhibited some toxicity in these assays, but at a lower potency than that of E. vannamei. The extracts of D. psammatodes and Polysyncraton sp. showed a strong inhibition of the sea urchin egg cell cycle during both phases examined, first cleavage and blastula, with a possible action on the cell microfilament apparatus. The extract of D. ligulum showed selective toxicity toward HCT-8 cells (IC₅₀=35.3 μg/ml). The extract from the Holozoidae was the only one that possessed a hemolytic effect, with an IC₅₀ of 175.2 μg/ml. Further studies are necessary for a better characterization of the active principles of these extracts and a possible elucidation of the mechanisms of action.     

Haliotrema cupensis n. sp. (Monogenea, Ancyrocephalidae) from a marine gobiid (Teleostei, Perciformes) of the Mediterranean coast

We describe a new ancyrocephalid monogenean, Haliotrema cupensis n. sp., from a marine gobiid, Gobius cobitis (Pallas) from the Mediterranean Sea. This species differs from the other members of the genus by the morphology of the penis and accessory piece, the haptoral ornamentation and by possessing a larger testis. This is the first report of an ancyrocephalid on a marine gobiid and of a Haliotrema species in the Mediterranean Sea.