Fungi parasitising the eggs of certain fresh water fishes

By the present investigations the parasitic abilities of five isolates of Saprolegniaceous fungi have been established on the eggs of three fresh water fishesviz., Channa marulius Ham.,Channa gachua Ham., andNotoptenis notopterus Ham. These fungi areAchlya orion CokerAchlya prolifera (Nees) De Bary,Aphanomyces laevis Minden andSaprolegnia ferax (Gruith) Thuret.     

Biochemical changes occurring during final maturation of eggs of some marine and freshwater teleosts

Biochemical changes which occur during post-vitellogenic meiotic maturation of oocytes were investigated by measuring the concentrations of various phosphorus-containing fractions of the ovaries and mature eggs of four marine species with pelagic eggs, plaice, Pleuronecles platessa , cod, Gadus morhua , haddock, Melanogrammus aeglefinus , and whiting, Merlangius merlangus , and three freshwater species with demersal eggs, rainbow trout, Salmo gairdneri , pike, Esox lucius , and powan, Coregonus lavarelus . In the former group, protein phosphate was deposited at normal vertebrate levels in the ovaries during vitellogenesis but was exhausted during maturation, its decrease correlating with the uptake of water which rendered the mature egg buoyant in sea water. In plaice, phospholipid phosphate declined slightly during maturation, while inorganic phosphate increased by an amount slightly less than that which disappeared from the protein fraction. No such changes occurred on maturation in these three fractions in the freshwater species, in which little or no water uptake occurred. In plaice, the approximately five-fold increase in the water content of the oocyte was accompanied by a corresponding five-fold increase in the amount of potassium, the major inorganic cation of the oocyte. These pelagic eggs appear to be unique among the eggs of vertebrates in their high water content ( c . 92%) and in the fact that the protein phosphate is almost entirely utilized before fertilization, while, in those freshwater fishes and other oviparous vertebrates that have been examined, the egg is of much lower water content (50–70%) and most of the protein phosphate, like the other major yolk constituents, is used during embryonic growth. This utilization at such an early stage in the life cycle constitutes an extreme example of heterochrony.     

The fatty acids of some marine teleosts

The lipids of five mesopelagic species of myctophid, two mesopelagic species of stomia-toid, and one epipelagic species of Macrorhamphosidae from the eastern-North Atlantic have been examined by thin-layer chromatography and their fatty acid compositions have been determined by gas-liquid chromatography.     

Olfactory responses to amino acids in marine teleosts

• 1.1. The olfactory responses to amino acids were recorded from the bulb of the red sea bream (Chrysophyrys major) and the conger eel (Conger myriaster).
• 2.2. The threshold concentration for l-glutamine was 10⁻⁷ M in the sea bream and below 10⁻⁸ and 10⁻⁹ M in the conger eel, and it was found that amino acids are good olfactory stimuli in both species.
• 3.3. A comparison of the olfactory spectrum of amino acids of the sea bream with that of each of three species of freshwater fishes revealed a high similarity of spectra.

     

The origin and structure of the zona pellucida in the ovarian eggs of teleosts

Summary An exhaustive study of the egg membranes of the oocytes of Trichiurus savala and Triacanthus brevirostris was made with particular reference to the origin and structure of the zona pellucida. The zona pellucida makes its first appearance as a deeply stained narrow zone of fine granular or amorphous homogeneous material around the oocytes, between the follicular epithelium and the vitelline membrane. This homogeneous substance is the product of the follicle cells. Very soon, radial striations in the zona pellucida get formed out of the homogeneous substance of the zona itself. The peripheral cytoplasm of the oocyte, by this time, also gets differentiated into a fibrillar layer. The follicle cells as well as the ooplasmic fibrillar layer send out a number of protoplasmic fibres towards each other into the canalicular passages of the radially striated zona. These fibres meet in the middle of the zona, differentiating it into two concentric zones, an outer—zona radiata externa and an inner-zona radiata interna. The former is purely follicular in origin, whereas the latter is partly follicular and partly ooplasmic in nature.     

Ventilatory responses of four marine teleosts to acute rotenone exposure

Ventilatory rate reponses of Diplodus bermudensis, Holocentrus rufus, Haemulon flavoleneatum and Haemulon sciurus to acute rotenone exposure were recorded by monitoring impedance changes accompanying opercular movements in individual specimens. Results identified two tolerance groups, each of which dislayed similar ventilatory response patterns but at different concentrations of rotenone. Exposure revels required to etablish opercular paralysis were found to be considerably less than that reported for 24 hour LC₅₀ of many freshwater organisms, indicating a high degree of toxic sensitivity for the four marine species examined.

Zusammenfassung

Ventilationsreaktion von vier marinen Teleosteirn bei akuter Rotenone-Exposition
Die Ventilationshäufigkeit von Dilodus bermudensis, Holocentrus rufus, Haemulon flavoleneatum und Haemulon sciurus gegenüber akuten Rotenone-Dosen wurde durch die Veränderung der Impedanz der Kiemendeckelbewegungen registriert. Die Ergebnisse zeigen zwei Toleranzgruppen, die jeweils ahnliche Ventilationshäufigkeiten erkennen lassen jedoch bei verschiedenen Rotenone-Konzentrationen. Die notwendige Konzentration für eine Lähmung der Kiemendeckelbewegungen war viel niedriger als die LC_50/24 für viele Süßwasserorganismen. Dieses zeigt die hohe toxische Sensibilität der vier untersuchten Arten gegenüber Rotenone.     

The toxicity of certain herbicides to hens' eggs assessed by the egg-injection technique

Twenty-five herbicides have been tested for their toxicity to hen embryos at various concentrations, using an egg-injection technique. Paraquat was the most toxic, giving a complete kill at a concentration in the egg of 0.3 ppm; two other compounds related to it were almost completely lethal at 10 ppm. Of the other compounds, seventeen had little or no effect at 50 ppm and of these eight had none at 100 ppm. Except for feather blanching, caused by some of the substituted phenoxy-acids, no teratogenic effects were found.     

Surface structure of the olfactory organ of marine teleosts

By means of the electron scanning microscope, structure of the olfactory rosella has been investigated in 5 species of marine Teleostei. Among the species investigated variability in number and arrangement is observed in the olfactory rosella folds. Arrangement order of the receptor and indifferent epithelia of the fold is presented by four types. Interspecies differences in organization of the sensory epithelium is revealed in ratio of various types of receptor and secretory cells. In Teleostei flagellar olfactory cells are the most numerous. In the Limanda yokohamae sensory epithelium certain flagella are described, that essentially differ by their size from usual receptor flagella and, evidently, are their complexes. The secretory cells are found in indifferent and sometimes in sensory epithelium as dark ostia; they are most numerous in mediosmatics. Some of the ostia are like wide craters and are, evidently, ostia of ducts of multicellular olfactory glands.     

Host range of Achlya prolifera (Nees) de bary on certain fresh water teleosts

Host range of Achlya prolifera (Nees) De Bary has been extended to Cotisa fasciatus, Colisa lalia, Puntius sophore, Notopterus chitala, and Anabas testudineus by conducting artificial inoculation experiments under controlled laboratory conditions.