Planktonic or non‐planktonic food in young‐of‐the‐year European perch Perca fluviatilis in ponds

Higher biomass especially of some aquatic macrophyte species offered a higher density of phytophilous zoobenthos, but did not increase the proportion of non‐planktonic to planktonic prey in young‐of‐the‐year perch Perca fluviatilis. Both abundance and biomass of non‐planktonic prey dominated over planktonic prey in the pond with lower biomass of aquatic macrophytes and lower food. Survival of P. fluviatilis was lower (20%) in the pond with lower food than in the other pond (34%), however, specific growth rate (1·3% day^?1) and final Fulton's condition factor of P. fluviatilis were similar in both ponds.     

Morphology and fine structure of Barbus barbus (Teleostei: Cyprinidae) spermatozoa

Morphology and fine structure of Barbus barbus L 1758 spermatozoa were studied using scanning (SEM) and transmission (TEM) electron microscopy. The results confirm that spermatozoa exhibit morphological features typical to all teleost fishes. They are differentiated into a head, a midpiece and a flagellum with the typical '9 + 2' pairs of microtubules. Both dynein arms are present in the flagellum. The spermatozoa have spherical nuclei, 4–6 mitochondria located in the postnuclear cytoplasmic region and centriolar complex (proximal and distal centrioles). Total length, head width, length of midpiece and length of flagellum were measured to be 56.35 ± 7.42, 1.80 ± 0.06, 0.48 ± 0.14 and 54.30 ± 6.97 μm, respectively. Highly significant linear correlation was observed between posterior and anterior width of midpiece (P < 0.01). Principal component analysis (PCA) was used to explore which parameters can explain the individual variation of sperm morphology. About 44% of the total accumulated variance was absorbed by the analysis of the two first components, distinguishing different groups of parameters related to head and midpiece. The lengths of flagellum and head are more isolated; indicating that the individual variation of sperm morphology depends on these two parameters. Comparing the results of this study with information on cyprinids spermatozoa reveals that the number of mitochondria and the length of the flagellum are good characters to characterize spermatozoa of the Cyprinidae in a phylogenetic arrangement.     

Spectroscopic investigation of isonitrile complexes of ferric and ferrous microperoxidase 8

Microperoxidase 8 (MP8) is able to react with alkyl- and aryl-isonitriles (RNC) both in its reduced and oxidized states, to form MP8Fe(II)- and MP8Fe(III)-CNR complexes. The coordination and spin states of these complexes have been fully characterized by UV-visible and resonance Raman spectroscopies. Both MP8Fe(II)- and MP8Fe(III)-CNR complexes are hexacoordinate low-spin complexes, which bear a single RNC ligand on the distal face of the heme and keep the His 18 ligand on its proximal face, trans to the RNC ligand. A comparison of these characteristics with those of the Fe-CNR complexes of other hemoproteins suggests that both MP8Fe(II)- and MP8Fe(III)-CNR complexes present a Fe-C-N linear arrangement. This may be due to the lack of any interactions of the RNC ligand with the octapeptide of MP8 that is mainly located over the opposite face of the heme. Finally the formation of hexacoordinate low-spin MP8Fe(II)- and MP8Fe(III)-CNR complexes constitutes a new example of the reactivity of MP8 with a new class of weak sigma-donating and strong pi-accepting ligands, which adds to its already very rich coordination chemistry.     

Relationship between semen characteristics and body size in Barbus barbus L. (Teleostei: Cyprinidae) and effects of ions and osmolality on sperm motility

The objectives of the present study were to determine the relationships among length and weight of males, sperm volume, spermatozoa concentration, total number of spermatozoa, ionic contents and osmolality of seminal plasma in Barbus barbus. The effect of osmolality on sperm motility parameters after activation in NaCl, KCl, or sucrose solutions was also examined. There were significant correlations between spermatozoa concentration – length (R = + 0.7) and – weight (R = + 0.8) of males. No significant correlations were observed between the total number of spermatozoa, sperm volume, and length and weight of males. Seminal plasma osmolality was higher when the total number of spermatozoa (R = + 0.6) and sperm volume (R = + 0.6) were higher. Sperm motility and velocity was positively correlated with osmolality (R = + 0.5). The correlation between sperm motility and K⁺ was negative (R = 0.5), but positively correlated with Ca²⁺ (R = 0.8), Na⁺ (R = 0.8), and Cl⁻ (R = 0.8). There was a rapid decrease (P < 0.05) in sperm motility parameters after sperm activation. Just after sperm activation, beating waves propagated along the full length of flagella. At latter stages post sperm activation, the waves appeared only in proximal part of the flagellum. The highest spermatozoa velocity and percentage of motility were observed at 215–235 mOsmol kg^− 1 in NaCl, KCl or sucrose. The tip of the flagellum became curled into a loop shape which shortened the flagellum after activation of sperm in distilled water. B. barbus sperm is very similar to that of other cyprinids in terms of ionic contents and osmolality of the seminal plasma, mechanism of sperm activation and behavior and motility of sperm during swimming period.     

Synthesis and superoxide dismutase-like activity of new manganese(III) complexes based on tridentate N2O ligands derived from histamine

We have obtained two new manganese(III) complexes based on tridentate ligands bearing imidazole and phenol moieties. The structure of the chosen ligands favored the Mn(III) oxidation state due to the compatibility of the geometry of the complexes with a Jahn-Teller tetragonal distortion, as was shown by X-ray diffraction for one of the complexes. This induced a lowering of the oxidation potential for the Mn(III)/Mn(II) couple, which can be correlated to the superoxide dismutase-like (SOD-like) activity of the complexes, compared with a previously published Mn(III) complex.     

Growth pattern of all‐female perch (Perca fluviatilis L.) juveniles – is monosex perch culture beneficial?

The study objective was to evaluate the enhanced profitability of monosex all-female stock (MS) culture compared to bisexual stock (BS) of Eurasian perch ( Perca fluviatilis L.) under intensive conditions. Monosex all-female stock was produced by mating masculinized females (neomales) with common females of a local strain; the bisexual stock was obtained from a local strain perch broodstock. Preceded by pond-nursing (60 days) and habituating (14 days) periods, the experiment lasted 126 days. Perch were held in six 50-L aquaria connected to a recirculation system, with each group tested in triplicate. No significant differences (P = 0.07) in total survival were observed between all-female and bisexual stock after 126 days of rearing, but MS gained 20% more (P = 0.04) in total body weight (final weight 25.2 ± 9.7 g; mean ± SD) than BS fish (21.0 ± 7.5 g). It is suggested that the culture of monosex female perch might therefore be of significant economic benefit. Overall feed conversion ratio for tanks with BS (1.43 ± 0.21) was significantly (P = 0.02) higher than in tanks with MS (1.30 ± 0.11) perch.