Assessment of the Toxic Effect of Zinc Ions and Nano-Sized Zinc Oxide on the Early Development of the Sand Dollar Scaphechinus mirabilis (Agassiz, 1864) (Echinodermata: Echinoidea)

Russian Journal of Marine Biology - Zinc ions and nano-sized zinc oxide had an embryotoxic effect on the sand dollar Scaphechinus mirabilis (Agassiz, 1864) at concentrations of 50–100...     

Effects of Desalination and the Detergent Sodium Dodecylsulphate on the Early Development of the Sand Dollar Scaphechinus mirabilis

We studied the effects of reduced water salinity on early ontogenesis in the sea urchin Scapechinus mirabilis. It is shown that the lower limit of salinity tolerance for the embryos and larvae is the salinity of 28. Under the mutual effects of desalination and sodium dodecylsulphate (SDS), an addition of 0.1 mg/l of the detergent to water with a salinity of 28 caused disturbances in the development of the larvae, starting from the stage of blastula. Desalination of the water down to 22 with the presence of SDS exerts significant effects already at the stage of fertilization. The mass death of embryos (73%) was observed at the stage of the first cleavage. The increase in the concentration of SDS up to 1 mg/l in water with a salinity of 28 to 22 caused an increase in the percentage of abnormal embryos and larvae from 40 up to 100%.     

Process of pigment cell specification in the sand dollar, Scaphechinus mirabilis

The process of pigment cell specification in the sand dollar Scaphechinus mirabilis was examined by manipulative methods. In half embryos, which were formed by dissociating embryos at the 2-cell stage, the number of pigment cells was significantly greater than half the number of pigment cells observed in control embryos. This relative increase might have been brought about by the change in the arrangement of blastomeres surrounding the micromere progeny. To examine whether such an increase could be induced at a later stage, embryos were bisected with a glass needle. When embryos were bisected before 7 h postfertilization, the sum of pigment cells observed in a pair of embryo fragments was greater than that in control embryos. This relative increase was not seen when embryos were bisected after 7 h postfertilization. From the size of blastomeres, it became clear that the 9th cleavage was completed by 7 h postfertilization. Aphidicolin treatment revealed that 10-15 pigment founder cells were formed. The results obtained suggest that the pigment founder cells were specified through direct cell contact with micromere progeny after the 9th cleavage, and that most of the founder cells had divided three times before they differentiated into pigment cells.     

A cyto-embryological study of gastrulation in the sand dollar, Scaphechinus mirabilis

Processes of gastrulation in the sand dollar Scaphechinus mirabilis were compared with those in the sea urchin Hemicentrotus pulcherrimus , which seemed to show a typical pattern of gastrulation. Measurement of the archenteron length clearly demonstrated that invagination processes in H. pulcherrimus are divided into two phases, the primary and secondary invagination. On the other hand, invagination in S. mirabilis was revealed to continue at a constant rate. To see the movement of cells during gastrulation, embryos were labeled with Nile blue. In H. pulcherrimus embryos, labeled cells were observed along the full length of the archenteron, if the embryos had been labeled before and during the primary invagination. Labeled cells were never observed in the embryos stained after the primary invagination. In contrast, labeled cells were always discerned at the basal part of the archenteron in S. mirabilis , even if the embryos were stained after invagination had undergone considerable progress. The number of cells in the archenteron of S. mirabilis embryos increased with the advancement of gastrulation, while the numbers were almost constant in H. pulcherrimus . These results suggest that the cellular basis of gastrulation in S. mirabilis is quite different from that in well-known species of sea urchins.     

Simple Method for the Preparation of Streptococcal Nucleases

A simple method for preparation and fractionation of the streptococcal nucleases by polyacrylamide gel electrophoresis is presented. The procedure is carried out with ammonium sulfate-precipitated supernatant fluids from cultures of beta-hemolytic streptococci grown to stationary phase. Electrophoresis on polyacrylamide gel and subsequent elution of the fractionated enzymes allows the preparation of sufficient homogeneous nuclease B for a large number of anti-nuclease B titrations.     

The Role of Intracellular pH in Fertilization of Sand Dollar Eggs Analyzed by Microinjection Method

The change in intracellular pH (pH_i) upon fertilization and the effects of changing the pH_i by microinjection of pH buffers were investigated in the eggs of the sand dollar, Clypeaster japonicus. The pH_i was determined by the tint of a pH indicator, phenol red, microinjected into eggs. The pH_i ranged from 6.5 to 6.75 in unfertilized eggs and it rose by 0.4 to 0.5 unit within 3 min upon fertilization. The elevated pH_i ranging from 7.0 to 7.25 was maintained at least until the first cleavage. As reported in eggs of other species of sea urchin (1–4), development of fertilized eggs which had been transferred to Na-free sea water immediately after insemination was arrested and the pH_i did not rise remaining at the level of unfertilized eggs. Development was initiated in eggs arrested in Na-free sea water when the pH_i was elevated up to the level of fertilized eggs, i.e. 7.0 to 7.25, by microinjecting 1 M HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-KOH buffer at pH 8.0. By microinjection of pH 7.5 buffer, some eggs started development though none of them underwent cleavage. By microinjection of pH 7.0 or pH 6.5 buffer, development was not initiated. The initiation of development depended on the pH value of microinjected pH buffer, and in consequence, on the final pH_i. The elongation of microvilli which had been arrested in eggs in Na-free sea water was also induced by microinjection of pH 8.0 or 7.5 buffer.     

Evolutionary trends in Hoplerythrinus unitaeniatus (Agassiz 1829) (Characiformes, Erythrinidae)

Hoplerythrinus unitaeniatus is a species of economic importance, widely distributed in the Brazilian territory. Many studies have reported the karyotypic variation that occurs in the species, which forms two groups according to the diploid number, one with 2n = 52 and the other with 2n = 48. In this work, three populations of H. unitaeniatus from different hydrographic basins were cytogenetically analyzed. The diploid number found was 2n = 48 for all populations, however, differences in karyotypic formula and fundamental number and heterochromatin distribution were also observed. Ag-NORs were multiple, GC-rich and when applied FISH with 18S rDNA bright signals in six chromosomes were observed. Data from this study confirm the occurrence of interpopulation variability in H. unitaeniatus. The basal number and the possible divergence among the different cytotypes analyzed for this species to date, as well as the forward the proposal of biogeographic and tectonic history for the continental margin are discussed.     

Use of environmental DNA to detect Eastern Sand Darter (Ammocrypta pellucida Putnam, 1863) in large Laurentian Great Lakes embayments

A single-species environmental DNA (eDNA) method was developed to sample for a small, benthic rare species, Eastern Sand Darter (Ammocrypta pellucida Putnam, 1863) in two large Lake Ontario embayments. Summer water sampling allowed for: (a) surveys of habitats (Wellers Bay) where traditional fish sampling gear could not be used; and, (b) a comparison between eDNA and seining-based detection probabilities at known occupied habitats (West Lake). In 2018, replicate (n = 3) 1 L water samples were collected from 90 Wellers Bay sites and 71 West Lake sites. A site-occupancy model, a hierarchical logistic regression model, was fitted to determine site occupancy, sample occupancy (presence of Eastern Sand Darter DNA in a water sample) and probability of detection (p) based on replicate quantitative polymerase chain reaction (qPCR) results for each water sample. Eastern Sand Darter was detected at 10 West Lake sites, but not from Wellers Bay. Mean site occupancy was 0.31 (0.12–0.70; 95% CLs), mean sample occupancy was 0.28 (0.09–0.58; 95% CLs), and mean detection probability in a subsample (i.e., successful qPCR amplification) given it was present was 0.40 (0.25–0.55; 95% CLs). While the eDNA method successfully detected Eastern Sand Darter from known occupied areas in West Lake, it was not more effective for assessing local site occupancy than traditional sampling methods, such as the seine.     

The integumental ultrastructure of Parathalestris harpactoides (Claus, 1863) (copepoda,harpacticoida)

The integument of Parathalestris harpactoides (Claus, 1863) is studied by scanning and transmission electron microscopy. The general structure of the integument conforms to the common pattern known from Copepoda. Emphasis is given to the structural variation of the cuticle in different regions of the body. The cuticle measures about 6 µm in most parts of the body, and shows a laminate appearance. The epicuticle is about 60 nm thick. Numerous pore canals containing muscular tonofilaments penetrate the procuticular layer of the integument. A peculiar feature is the presence of a honeycombed layer in the outermost zone of the cuticle of some parts of the body. The epidermal layer, muscle insertions and integumental pores are of common type. The cuticle of some specimens, both males and females, is covered with microorganisms.     

A Simple Method for Preparation of Poly-mannuronate Using Poly-guluronate Lyase

A simple method for preparation of poly-mannuronate from alginate has been developed. By making the best use of the substrate specificity of a poly-guluronate lyase, we prepared a poly-mannuronate of which the properties were almost identical to those of the poly-mannuronate produced by Haug’s acid hydrolysis method. Our method is very useful in terms of time and labor saving.     

Late Cretaceous sharks from Cuba,first record of Serratolamna serrata (Agassiz) (Lamniformes,Serratolamnidae)

Only one species of Elasmobranchii, Ptychodus cyclodontis Mutter, Iturralde-Vinent and Carmona (2005), has been reported so far from the Late Cretaceous of Cuba. Herein we describe the first record of a Maastrichtian Serratolamna serrata (Agassiz, 1843) as well as non-diagnostic remains which include a tooth referred to a lamniform shark and an isolated vertebra of an indeterminate elasmobranch. These fossils expand the temporal distribution of Cretaceous fossil sharks known from Cuba and increase our understanding of the group’s fossil diversity.     

A Method of Raising Clones of the Hydroid Phialidium gregarium (A. Agassiz, 1862) in the Laboratory

The hydroid Phialidium gregarium can be successfully culturedto sexual maturity at any time of the year and maintained foryears in a closed system marine aquarium. Artificial sea waterwas used in place of natural sea water and was renewed by one-quarterof its volume each 4 weeks, Freshly hatched Artemia naupliiwere used as the sole food source. Methods for obtaining coloniesof a single genotype from planulae are described. Subculturingpieces from parental stock is accomplished by a new method.A new technique for removing hydroid colonies from their substratefor histological study is described.     

Structural Features of Spines in Some Rodents (Rodentia: Myomorpha, Hystricomorpha)

The architectonics of spines and hair was studied in Neacomys spinosus, Tokudaia osimensis, Arvicanthis somalicus, Leopoldamys sabanus, L. edwardsi, Maxomys moi, M. surifer, Niviventer fulvescens, N. confucianus, N. cremoriventer, Acomys cahirinus, A. somalica, Hystrix indica, H. cristata, Atherurus macrourus, Erethizon dorsatum, Proechimys steerei, and Lonchotrix emiliae. The presence of a dorsal longitudinal furrow covered by a modified cuticle is a common structural feature of spines in all studied species except E. dorsatum, H. indica, and H. cristata. The frontal surface of the mosaic (scales located side by side) and terrace cuticle (steps between scales) varies in different species from smooth to rib-folded. A terminology has been proposed to describe the main structures of spine and hair. The adaptive significance of the spine architectonics in rodents is discussed.     

A Simple Method for the Preparation of D-α-Aminoadipic Acid

Abstract

High quantity (1 g and more) of racemically and chromatograph-ically pure D-α-aminoadipic acid was Drepared by selective metabolism of the L-isomer of the commercially available DL-α-aminoadi-pate by Pseudomonas putida. The overall yield of this preparation averaged 40%. The final product has a [a]²⁵ _D value of ?25°. This procedure can be useful in the synthesis of high purity D-α-amino-adipate, a compound shown recently to be a useful tool in the study of neurotransmission mechanism mediating synaptic excitation.     

A Simple Biosynthetic Method for Preparation of High Specific Radioactivity Phosphatidyl-choline

Chemical changes in lysozyme during heating at 150~250°C for 20min were investigated by means of IR, ESR, and CD spectroscopies and gel permeation chromatography, and further a tryptic hydrolysate from the lysozyme heated at 200°C was analyzed by ion exchange chromatography. At 150°C, polymerization through disulfide linkages was observed, and at180°C, both polymerization and degradation occurred. When the temperature was raised to 200°C, remarkable changes in the structure of lysozyme, such as cleavage and recombination of peptide bonds, occurred. Over 200°C, polymerization and degradation occurred more violently.