Length–weight and length–length relationships for three Sillago species (Sillaginidae) from the Persian Gulf

This study investigates length–length and length–weight relationships of three Sillago species [Sillago arabica McKay & McCarthy (Memoirs of the Queensland Museum, 27, 1989, 551), Sillago attenuata McKay, 1985 and Sillago sihama (Forsskål, 1775)] captured in the Persian Gulf, Iran. A collection of 220 specimens was captured from August 2015 to January 2016 by cast net (mesh size: 10 mm) and beach seine (mesh size: 15 mm). The relationships of total length (TL) and standard length (SL) and the relationships between total length and body weight are given. This study presents the first reference on LWRs for two of the species (S. arabica and S. attenuata) in their range of distribution.     

Length–weight relationships of five commercial fish species from the Strait of Hormuz in the Persian Gulf

Length‐weight relationships are described for five fish species from the coast of the Hormuz Strait in the Persian Gulf, Iran. Specimens were collected between August 2010 and July 2011 using shrimp beam trawls, gill nets and intertidal fishing weirs. Relationships for three of the species had no previous data in the international science global databank on fishes: www.FishBase.org . A new maximum length was recorded for Acanthopagrus latus.     

Finite element prediction of fatigue damage growth in cancellous bone

Cyclic stresses applied to bones generate fatigue damage that affects the bone stiffness and its elastic modulus. This paper proposes a finite element model for the prediction of fatigue damage accumulation and failure in cancellous bone at continuum scale. The model is based on continuum damage mechanics and incorporates crack closure effects in compression. The propagation of the cracks is completely simulated throughout the damaged area. In this case, the stiffness of the broken element is reduced by 98% to ensure no stress-carrying capacities of completely damaged elements. Once a crack is initiated, the propagation direction is simulated by the propagation of the broken elements of the mesh. The proposed model suggests that damage evolves over a real physical time variable (cycles). In order to reduce the computation time, the integration of the damage growth rate is based on the cycle blocks approach. In this approach, the real number of cycles is reduced (divided) into equivalent blocks of cycles. Damage accumulation is computed over the cycle blocks and then extrapolated over the corresponding real cycles. The results show a clear difference between local tensile and compressive stresses on damage accumulation. Incorporating stiffness reduction also produces a redistribution of the peak stresses in the damaged region, which results in a delay in damage fracture.     

The LPS O-Antigen in Photosynthetic Bradyrhizobium Strains Is Dispensable for the Establishment of a Successful Symbiosis with Aeschynomene Legumes

The photosynthetic bradyrhizobia are able to use a Nod-factor independent process to induce nitrogen-fixing nodules on some semi-aquatic Aeschynomene species. These bacteria display a unique LPS O-antigen composed of a new sugar, the bradyrhizose that is regarded as a key symbiotic factor due to its non-immunogenic character. In this study, to check this hypothesis, we isolated mutants affected in the O-antigen synthesis by screening a transposon mutant library of the ORS285 strain for clones altered in colony morphology. Over the 10,000 mutants screened, five were selected and found to be mutated in two genes, rfaL, encoding for a putative O-antigen ligase and gdh encoding for a putative dTDP-glucose 4,6-dehydratase. Biochemical analysis confirmed that the LPS of these mutants completely lack the O-antigen region. However, no effect of the mutations could be detected on the symbiotic properties of the mutants indicating that the O-antigen region of photosynthetic Bradyrhizobium strains is not required for the establishment of symbiosis with Aeschynomene.     

Electrophysiologic study of rabbit proximal tubular cell monolayers in primary culture

Primary cultures of renal cortical cells prepared by selective sieves have been found to display some characteristics of renal proximal tubular epithelium but their site of origin has not been confirmed by electrophysiologic studies. Cells were cultured in a defined medium on collagen gels. Confluency was approached after 7-10 days but gels were found to have zero transepithelial resistance unless they were allowed to contract spontaneously. With the appearance of a nonzero resistance, there was a change in morphology to a more columnar cell with better developed microvilli. These structural features were particularly prominent in clusters of proliferating cells observed on and around remnants of original tubules embedded in the gel. In noncontracted cultures there was no focal cell clustering and cells were squamous-like with rudimentary microvilli, similar in appearance to cells grown on plastic culture dishes. Measurements made in contracted monolayers yielded an average transepithelial resistance of 6.5 omega cm2, a spontaneous transepithelial potential difference of +0.9 mV, measured with respect to the serosa, and an apical membrane potential of -75 mV when cells were bathed in 0.4 mM K and -49 mV when cells were bathed in 4 mM K media. Mucosal protamine (50 micrograms/ml) increased transepithelial resistance by 22%, suggesting that the epithelial cell tight junctions were responsive to external stimuli. Monolayers were anion selective, giving a dilution potential (lumen-directed NaCl gradient) of -2.6 mV with respect to the serosa. These experiments show that primary culture of rabbit renal cortical cells separated by differential sieves displays electrophysiologic and morphologic characteristics of a proximal renal tubular epithelium. Confluency and attainment of differentiated morphology and function are promoted when monolayer cells are not bound to an unyielding substrate.     

Sulfated proteoglycans of rabbit aorta: selective extraction and alternative method for glycosaminoglycan moiety analysis.

Three different solutions containing urea, guanidine hydrochloride, or a detergent mixture were used to extract proteoglycan molecules (PG) metabolically labeled with 35S from normal rabbit aortic tissue. The size distribution of whole sulfated PG and the glycosaminoglycan (GAG) compositions in the three extracts were compared and found to be characteristically determined by the type of solution used for extraction. The spectrum of sulfated PG isolated by each solution was maintained at consecutive extractions of the tissue, even if this was used after another type of solution. The extracts obtained by using the urea- or guanidine-containing solutions contained similar, rather balanced populations of large and small PG, while the detergent-containing buffer was found to preferentially extract smaller, heparan sulfate-rich aortic PG. The selectivity of various extracting solutions could be exploited to obtain preparations enriched in certain types of sulfated PG. On the other hand, one could obtain a larger variety of 35S-labeled PG from the tissue by consecutively using two solutions with different capacities of extraction. The distribution of GAG moieties among PG populations, separated by size chromatography, was investigated by one of the commonly used methods and by a new method. The standard method is based on comparison of the chromatographic profiles of the extract before and after enzymatic digestions, requiring several chromatographic runs for a sample. In the alternative method proposed, the fractions obtained after a single chromatographic separation are adsorbed onto a support membrane. Processing of the whole membrane by GAG-specific, enzymatic treatments allows simultaneous assessment of GAG types in each fraction.(ABSTRACT TRUNCATED AT 250 WORDS)     

RELATIONSHIP BETWEEN NUCLEO-CYTOPLASMIC RATIO AND FINAL CELL VOLUME IN MICRASTERIAS CRUX-MELITENSIS (DESMIDIACEAE,CHLOROPHYTA)1

In Micrasterias crux-melitensis (Ehrbg.) Hass., small parental half-cells produced daughter half-cells larger than themselves. As the volume of the parental half-cells decreased, the volume ratio of daughter to parental half-cells increased; the larger the nucleo-cytoplasmic ratio of parental half-cells, the larger the volume of the daughter half-cells. Small daughter half-cells grew larger than expected when cytoplasm of other cells was incorporated. The number of dictyosomes was almost the same for cells of different volumes. Results obtained seem to suggest that the volume of daughter cells is determined by the balance between the gradient of mRNA and the quantity of cytoplasm.     

Motility of Mugil cephalus L. spermatozoa in coelomic fluid, seminal fluid and saline media

The aim of this study was to assess the motility duration of Mugil cephalus when exposed to seminal fluid, coelomic fluid and saline media. Hypo-osmotic activation medium (distilled water containing bovine serum albumin 10 or 30 mg ml⁻¹) did not trigger sperm motility. Saline solution containing 500 m m NaCl, 3.1 m m KCl, 0.2 m m Tris, 3.4 m m CaCl₂, pH 7.5 initiated the sperm activation and the motility lasted for more than 2 min. Coelomic fluid showed an inhibitory effect for triggering the motility of spermatozoa. Higher salinity increases the motility duration of sperm. The optimum motility duration was shown in salinity 32 psu.