Carbon assimilation during larval development of the marine teleost Leiostomus xanthurus Lacépède

In larval spot, Leiostomus xanthurus Lacépède, ¹⁴C labeled food was rapidly digested and assimilated with up to 20% respired as ¹⁴CO₂ within 10 h from ingestion. Two indices of carbon assimilation, total carbon utilization (range 9.4 to 64.7%) and total carbon absorption (range 67.2 to 99.2%) were calculated from the amount of ¹⁴C ingested, retained, and defecated. Carbon utilization and absorption were not significantly (P > 0.10) related to development as measured by age (7 to 47 days from hatching), length (1.8 to 11.4 mm), or dry weight (0.022 to 4.425 mg).     

Feeding kinematics and morphology of the alligator gar (Atractosteus spatula,Lacépède, 1803)

Living gars are a small clade of seven species that occupy an important position on the actinopterygian phylogenetic tree as members of Holostei, sister-group to teleosts, and exhibit many plesiomorphic traits used to interpret and reconstruct early osteichthyan feeding mechanisms. Previous studies of gar feeding kinematics have focused on the ram-based, lateral-snapping mode of prey capture found in the narrow-snouted Lepisosteus genus, whereas this study focuses on a member of the broad-snouted Atractosteus sister-genus, the alligator gar (Atractosteus spatula, Lacépède, 1803). High-speed videography reveals that the feeding system of alligator gars is capable of rapid expansion from anterior to posterior, timed in a way to generate suction, counteract the effects of a bow-wave during ram-feeding, and direct a unidirectional flow of water through the feeding system. Reconstructed contrast-enhanced μCT-based cranial anatomy and three-dimensional modeling of linkage mechanics show that a lateral-sliding palatoquadrate, flexible intrasuspensorial joint, pivoting interhyal, and retractable pectoral girdle increase the range of motion and expansive capabilities of the alligator gar feeding mechanism. Reconstructions of muscular anatomy, inferences from in vivo kinematics, and in situ manipulations show that input from the hyoid constrictors and hypaxials play an important role in decoupling and modulating the dual roles of the sternohyoideus during feeding: hyoid retraction (jaw opening) and hyoid rotation (pharyngeal expansion). The alligator gar possesses an intricate feeding mechanism, capable of precise control with plesiomorphic muscles that represent one of the many ways the ancestral osteichthyan feeding mechanism has been modified for prey capture.     

Differential expression for tissue-specific isozymes in three species of Hypostomus Lacépède, 1803 (Teleostei: Loricariidae)

The expression patterns of 14 enzymatic systems in skeletal muscle, liver and heart tissues of three species of Hypostomus from the Iguaçu River basin (Brazil) were investigated. Although the patterns were similar for the three species, different tissues showed differential expressions, and the data showed that differential tissue expressions of isoperoxidases may be due to preferential combination or association of polypeptide subunits. The detected patterns for SOD isozymes showed that the quaternary structures of these enzymes were in disagreement with the subunit number reported for the majority of other vertebrate groups. Tissue-specific restriction on heterotetramer formation also were described in LDH and MDHP isozymes. Thus, these tissue-specific gene expression character in the species of Hypostomus have the greatest potential to be recognized and applied in systematic studies among species of Hypostomus.     

Karyotypic diversification in Hypostomus Lacépède, 1803 (Siluriformes, Loricariidae): biogeographical and phylogenetic perspectives

Hypostomus is a species-rich genus of fish with unclear systematics and phylogenetic relationships. Ten species of Hypostomus (H. albopunctatus, H. ancistroides, H. cochliodon, H. commersoni, H. faveolus, H. hermanni, H. aff. paulinus, H. regani, H. strigaticeps and H. topavae) were cytogenetically analyzed through Giemsa staining and silver nitrate impregnation, and the obtained data were correlated to the available biogeographical and phylogenetic analyses for the genus. Although the silver stained nucleolar organizer regions (AgNORs) were found to vary significantly among the species, the diploid numbers could be correlated to the distribution of the species on northern and southern South America river basins. Species with the lower diploid numbers (2n = 64) were associated to northern hydrographic basins and showed a single AgNORs bearing pair. Diploid numbers of 66–68 chromosomes and of 70–84 chromosomes were correlated to two major clades within Hypostomus and southern hydrographic basins, and showed AgNORs varying on number and position. Our results show that cytogenetic data can be correlated to the phylogeny and biogeography of the genus, helping to clarify its complex evolutionary history.     

Molecular inferences about the genus Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae): a review

This review compiles and discusses the use of genetic markers applied in the study of the fish genus Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae). The database comprises 51 peer-review articles that were published in the last 52 years (1968–2020) and that approach analysis based on different classes of genetic markers. The use of cytogenetic and enzymatic markers was predominantly especially in population studies with the genus Hypostomus, while mitochondrial markers were the majority in phylogenetic studies. Although significant methodological advances have occurred for molecular evaluation, they are still modestly applied to the study of neotropical fish genera, in which Hypostomus is included. New perspectives, especially on integrative approaches, are needed to improve our knowledge of the genetic functionality of fishes.

     

Comparison of ageing methods and growth rates for largemouth bass,Micropterus salmoides Lacépède,from northern latitudes

Synopsis Ages determined by counts of apparent annuli on scales, sagittae, vertebrae, pectoral fin ray and dorsal fin spine cross sections of largemouth bass from northern populations, which are older and slower growing fish than in the southern parts of its native range, were compared to establish the accuracy of each method. Linear regression techniques indicated strong agreement (r> 0.9) among ages assigned from the examination of scales, sagittae, and vertebrae. The pattern of growth zones on pectoral fin ray and dorsal fm spine cross sections proved too variable for accurate age determination. Limited data suggest that ages greater than 7+ assigned from scales were more likely to underestimate true ages than the other body parts used, although none of these methods gave satisfactory results. Examination of scales from recovered tagged fish, and the similarity between back-calculated lengths of fish through age 7+ to annulus I and observed lengths of juvenile largemouth bass near the end of their first growing season, support the validity of ages determined from scales. Despite a very limited amount of habitat suitable for largemouth bass and severe climatic conditions, growth of this species in Tadenac Lake was similar to growth in other waters north of the Great Lakes. Differences in physical characteristics among these waters does not appear to influence growth rates of largemouth bass, but probably affects production and biomass.     

High concentrations of viruses in the sediments of Lac Gilbert, Québec

Viruses were found to be very abundant in the top layer of the sediments of Lac Gilbert, Québec. Viruses were extracted from the sediments using pyrophosphate buffer, and viruses from the diluted extracts were pelleted onto grids and enumerated using transmission electron microscopy. Viral abundance in the sediments ranged from 6.5 × 10⁸ to 1.83 × 10¹⁰ ml^–1, which is 10- to 1,000-fold greater than the number observed in the water column. This increase corresponds well with the 100- to 1,000-fold increase in bacterial abundance in the sediments. Viral abundance differed significantly among the surface sediment samples taken at different bottom depths and among samples taken at different depths of the water column. Viral abundance also varied significantly between the oxic and anoxic zones of the water column and the sediments. The virus-to-bacteria ratio varied greatly among the different sediment sites but not among depths in the water column. Viral abundance in the water column was related to bacterial abundance and chlorophyll concentration, whereas viruses in the sediments were most abundant in sediments with high organic matter content. Elevated viral abundance and their erratic distribution in the sediments suggest that viruses might play an important role in sediment microbial dynamics. Correspondence to: Roxane Maranger     

Comparative studies of bile salts. 5α-Chimaerol, a new bile alcohol from the white sucker Catostomus commersoni Lacépède

1. G.l.c. examination of bile alcohols prepared from the sucker Catostomus commersoni Lacépède (family Catostomidae) showed that although 5α-cyprinol (5α-cholestane-3α,7α,12α,26,27-pentol) was a minor constituent, the principal bile alcohol was an undescribed substance, probably present in the bile as the C-26 sulphate ester, whose i.r., n.m.r. and mass spectra agreed with the structure 5α-cholestane-3α,7α,12α,24,26-pentol. 2. M_D studies suggest that this 5α-chimaerol is the 24(+), 25S enantiomer and that 5β-chimaerol (chimaerol) from Chimaera monstrosa bile also has the 24(+), 25S configuration. These findings imply that bile alcohol biosynthesis in suckers and chimaeras includes stereospecific oxidation of cholesterol at C-26. 3. C. commersoni bile acids (present in minor amounts) probably consist largely of 3α,7α,12α-trihydroxy-5α-cholan-24-oic acid (allocholic acid). 4. 5α-Chimaerol sulphate and 5α-cyprinol sulphate are probably biochemically equivalent as bile salts, and can be considered as arising by parallel evolution.     

Trends in chromosome evolution in the genus Hypostomus Lacépède, 1803 (Osteichthyes, Loricariidae): a new perspective about the correlation between diploid number and chromosomes types

Phylogenetic relationships and identification of species of the genus Hypostomus is still unclear. Considering this, cytogenetics may prove itself as an important tool in understanding the systematic of this genus. Reviews in Hypostomus indicate that the diploid number ranges from 54 to 84 chromosomes, and the increase in diploid number has been associated to higher percentages of subtelocentric and acrocentric chromosomes. Although there is a high number of species in the genus, there are relatively few papers concerning Hypostomus cytogenetics, and most of the data is published as grey literature. With the aim to understand the chromosomal evolution in the genus (correlation between diploid number x chromosomes types), H. ancistroides and H. topavae from the Piquiri River, Upper Paraná River basin, were cytogenetically analyzed, and the diploid number observed was 68 and 80 chromosomes, respectively. Additional data on the diploid number and chromosome formulae was compiled from papers (27 analyses) and abstracts from grey literature (77 analyses). Our analysis shows no correlation between chromosome numbers and percentages of subtelocentric and acrocentric chromosomes for most of the species, since there is considerable variation between these percentages even between species with the same diploid number, indicating that the proportion of chromosome types is not always associated to diploid numbers.     

A New Species of Trimeresurus Lacépède, 1804(Squamata: Viperidae) from Southwestern China,Vietnam, Thailand and Myanmar

The pit vipers of the genus Trimeresurus Lacépède, 1804 is one of the largest groups of Asian snakes, distributed from India to China and Indonesia. Recent surveys in Jiangcheng and Simao, Yunnan Province, China resulted in a new species previously allocated to T. albolabris. Combining morphological and molecular data, we describe it as Trimeresurus guoi sp. nov. The new species morphologically differs from T. albolabris in the yellow green ventral color; an indistinct ventrolateral line; the a bsence of a postocular stripe; the firebrickred iris; a dark red stripe on dorsal tail; hemipenes with relatively weak sparse papillae, reaching 23 rd subcaudal when unextruded. Molecularly, the new species forms a clearly divergent lineage(BPP 1.00/UFB 100). Uncorrected pairwise distances of mitochondrial gene Cyt b between the new species and other known species of the subgenus Trimeresurus range from 0.052(T. albolabris) to 0.071(T. insularis).     

Previtellogenic oocytes of South African largemouth bass Micropterus salmoides Lacépède 1802 (Actinopterygii,Perciformes) - the Balbiani body,cortical alveoli and developing eggshell

The ovaries of the largemouth bass Micropterus salmoides, an alien and invasive species in South Africa, contain a germinal epithelium which consists of germline and somatic cells, as well as previtellogenic and late vitellogenic ovarian follicles. The ovarian follicle consists of an oocyte surrounded by follicular cells and a basal lamina; thecal cells adjacent to this lamina are covered by an extracellular matrix. In this article, we describe the Balbiani body and the polarization and ultrastructure of the cytoplasm (ooplasm) in previtellogenic oocytes. The nucleoplasm in all examined oocytes contains lampbrush chromosomes, nuclear bodies and several nucleoli near the nuclear envelope. The ultrastructure of the nucleoli is described. Numerous nuage aggregations are present in the perinuclear cytoplasm in germline cells as well as in the ooplasm. Possible roles of these aggregations are discussed. The ooplasm contains the Balbiani body, which defines the future vegetal region in early previtellogenic oocytes. It is comprised of nuage aggregations, rough endoplasmic reticulum, Golgi apparatus, mitochondria, complexes of mitochondria with nuage-like material, and lysosome-like organelles. In mid-previtellogenic oocytes, the Balbiani body surrounds the nucleus and later disperses in the ooplasm. The lysosome-like organelles fuse and transform into vesicles containing material which is highly electron dense. As a result of the fusion of the vesicles of Golgi and rough endoplasmic reticulum, the cortical alveoli arise and distribute uniformly throughout the ooplasm of late previtellogenic oocytes. During this stage, the deposition of the eggshell (zona radiata) begins. The eggshell is penetrated by canals containing microvilli and consists of the following: the internal and the external egg envelope. In the external envelope three sublayers can be distinguished.     

The corneous layer of the claw in the lizard Anolis carolinensis mainly contains the glycine–cysteine-rich beta-protein HgGC3 in addition to hard keratins

The localization of specific claw beta-proteins among the 40 total corneous beta-proteins present in the lizard Anolis carolinensis is not known. The hardness of claws likely depends on glycine–cysteine-rich beta-proteins content, as suggested by previous immunoblot studies. Previous studies have indicated that glycine–cysteine-rich corneous beta-proteins in addition to cysteine-rich alpha-keratins are present in the claw. In order to detect at the ultrastructural level the presence of claw-specific corneous proteins immunofluorescence and electron microscopy immunogold have been utilized. More intense immunoreactivity is obtained for the HgGC3 beta-protein while less intense immunolabeling is seen for HgGC10 and HgG5 beta-proteins and no labeling for the cysteine-rich beta-protein HgC1. The HgGC3 beta-protein appears the prevalent type present in the claw and its numerous cysteines likely form intermolecular disulphide bonds while glycine contributes hydrophobic properties to the corneous material. Other antibodies tagging the core-box and pre-core box regions of beta-proteins label with less intensity the corneous layer. The presence of cysteine-rich alpha-keratins with high homology to some human hair keratins in the dorsal part of the claw suggests that HgGC3-like beta-proteins form numerous disulphide bonds with the larger alpha-keratins giving rise to the hard corneous material of the claw.     

Immunocytochemical localization of α-melanocyte-stimulating hormone in the brain of the lizard,Lacerta muralis

Summary The distribution of -melanocyte-stimulating hormone (-MSH) was studied in the brain of the lizard Lacerta muralis by means of immunocytochemical staining methods. -MSH-like containing cells were found in the ventro-lateral preoptic area and the paraventricular and supraoptic nuclei. Some scattered cells staining for -MSH were also detected in the mesencephalo-diencephalic boundary region, while numerous -MSH-like nerve fibres were localized in the medial eminence. No reaction was observed after the use of antiserum preabsorbed with synthetic antigen.These findings suggest that an -MSH-like peptidergic system could possibly be involved in the hypothalamo-hypophysial regulation and/or play a role as neurotransmitter in this animal.     

Studies on the Flavors in Saké

A very small amount of vanillin was found in Saké, but the mechanism of its formation during Saké brewing has not yet been elucidated. Therefore, shaking culture of a Saké yeast (Kyokai No. 7 strain) was carried out in the Hayduck’s solution containing ferulic acid which was considered to be a precursor of vanillin. By the analysis of the fermentation products, formation of p-hydroxybenzoic acid and vanillic acid was elucidated. On the other hand, in the similar experiment using vanillin in place of ferulic acid, p-hydroxybenzoic acid, p-hydroxybenzaldehyde and vanillic acid were identified.

On these results, it was suggested that vanillin might be formed as an intermediate of the degradation reaction of ferulic acid, and also, the demethoxylation of vanillin might be occurred in the fermentation of yeast.     

When destruction comes first: Two new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from a deeply-impacted river in the Rio São Francisco basin in Brazil

Environmental disasters affecting Brazilian rivers have been frequent recently, especially involving mining activities. Two recent dam-rupture events suddenly released millions of cubic meters of iron tailings downstream into two major Brazilian watersheds. These events generated major losses to the environment and human life. Additionally, the biodiversity in both watersheds was still incompletely known. Two new species of the armoured catfish genus Hypostomus were discovered in the Rio Paraopeba and surrounding rivers of the Rio São Francisco Basin. The species share some main characteristics including a depressed body, large dark spots on a clearer background and the absence of keels on flanks. However, while one species (Hypostomus freirei sp. n.) has a large mandibular ramus and numerous slender teeth, the other (Hypostomus guajupia sp. n.) has a shorter mandibular ramus and few robust teeth. The discovery of these two new mid-sized fish species emphasizes the presumption that the effects of major environmental disasters cannot be fully estimated as local biodiversity is not completely known. This discovery in a recently devastated area also shows that tough environmental laws for the protection, supervision and mitigation of major impacts are urgently needed in developing countries.     

Studies on the Fluorescence of Saké

By spectrofluorophotometric investigation on various kinds of Saké it was found that they have at least two kinds of fluorescent colors, the one is blue, the other yellowish green. The former is always more dominant than the latter, but is unstable although the intensities of both color decrease remarkably by treatment of active charcoal. Ferulic acid and harman as the blue fluorescent components are isolated, the former from Saké in young, the latter from Saké kept for a long time under direct sun light.     

The manganese cycle in Lac Léman,Switzerland: the role ofMetallogenium

The manganese pathways in Lac Léman have been investigated on the basis of chemical analyses undertaken on water, suspended solids, bottom sediments and interstitial water samples. The various modes of occurrence of Mn have been determined by means of visual examination using SEM and TEM (scanning and transmission electron microscopy), by microanalysis (EDAX) of various sediment fractions, by chemical analysis of the dissolved phase, and by chemical speciation and XRD of bottom sediments. Fluxes to and from the sediment have also been computed. The time-depth variations of Mn in the water column are characterized by (a) a very steep gradient of Mn sol. from the sediment interstitial water (15 mg l⁻¹) to the overlying water, 2 m above the bottom(500 μg l⁻¹), (b) an accumulation of Mn part. between 280 m and the interface at 310 m, consisting of mineralized colonies ofMetallogenium. The abundance ofMetallogenium colonies is inversely related to O₂ concentration; the optimal value for the bacterium Mn fixation is around 1 mg l⁻¹. Because of the quasi-anoxic state of the bottom sediments and overlying water, Mn diffuses from a ‘source layer’, 2–5 cm below the interface (a) upwards across the interface, before being taken up byMetallogenium, and (b) downwards to a ‘sink layer’, in which large amounts of Mn-carbonate precipitate. Particulate Mn sedimentation rates measured in traps show that downwards Mn flux due toMetallogenium settling approximately balances the upwards soluble flux due to diffusion. Quantitatively, the process of Mn cycling in Lac Léman is, therefore, limited to the lowermost part of the hypolimnion. Although Zn and Cd seem to follow the same cycle as Mn, Fe behaves in a different manner; it was not taken up byMetallogenium at the time of our study.     

A phylogenetic analysis of body size evolution in the Anolis roquet group (Sauria: Iguanidae): character displacement or size assortment?

The important role that competition plays in structuring communities is well documented; however, the role of competition in an evolutionary context remains unclear. Evolutionary investigations into the role of competition have often focused on the process of character displacement, and a good example of this is the evolution of body size in the Anolis lizards of the Caribbean islands. Previous work on the A. roquet species group has taken a phylogenetic approach and concluded that patterns of body size differences are not caused by character displacement but are a result of size assortment. Using a phylogenetic reconstruction based on the sequence of the cytochrome b gene (cyt-b) and ancestral character-state reconstruction methods, we investigated the roles of character displacement and size assortment. Our results indicated that size assortment alone was insufficient to explain the observed patterns of body size differences. Furthermore, we found that change in body size was associated with a change in allopatry/sympatry, thus supporting the character-displacement hypothesis. We conclude that patterns of body size differences in the A. roquet species group appear to be the result of a combination of character displacement and size assortment because character displacement was only found to be possible on three occasions.