The radial decline of nerve impulses in a restricted cylindrical extracellular space

In order to increase the potentials recorded extracellularly from nerve fibres, peripheral nerves are often placed in restricted space with cylindrical geometry. Equations are derived for computing the potentials expected at the surface of the cylinder, based on the potentials at the external surface of a small nerve fibre located on the long axis of the cylinder. These equations are evaluated numerically, using two formulae for a nerve impulse given in the literature. In both cases there is little attenuation for cylinders with radii less than 0.5 mm, but the potential declines approximately as a power of radius b for 1<b<10 mm. Various factors which might affect these results under different experimental conditions are discussed.     

Insecticidal effects of some biological agents on Agelastica alni (Coleoptera: Chrysomelidae)

The alder leaf beetle (Agelastica alni L., Coleoptera: Chrysomelidae) causes approximately 10% of total economic damage to hazelnut product per year in Turkey. A. alni larvae are susceptible to several pathogens indigenous to the area in which these insects occur in Turkey. In the present study, in order to find a more effective and safer biological control agent against this common pest, we evaluated the various biological agents’ insecticidal activity during the four hazelnut seasons from 2002 to 2005 on the larvae of the alder leaf beetle collected from the vicinity of Trabzon, Turkey. The tested agents are 25 insect-originating bacteria, 2 bacterial toxins and 1 viral preparation. The results showed that the highest insecticidal activity was obtained by bacterial isolates at 1.8 × 10⁹ bacteria/mL dose, within ten days on the larvae of A. alni. These are 90% for Bacillus thuringiensis biovar tenebrionis (4AA1), Bacillus sphaericus (Ar4, isolated from Anoplus roboris L., Col.: Curculionidae), and Bacillus thuringiensis (Mm2, isolated from Melolontha melolontha L., Col.: Scarabaeidae). Our results indicate that these isolates may be valuable as biological control agent.     

Changes in fatty acid composition,cholesterol and fat‐soluble vitamins during development of eggs and larvae in shabbout (Barbus grypus,Heckel 1843)

Changes in fatty acid composition, cholesterol and fat‐soluble vitamins were studied during development (fertilized eggs, yolk‐sac larvae, and after yolk resorption of shabbout, Barbus grypus). Significant differences were found in the monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFA), PUFA/saturated fatty acids (SFA), ∑n‐3 and eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) ratios between eggs and larvae (P < 0.05). Significant differences were also observed in the C14:0, C16:1n‐7, C18:1n‐9, C18:3n‐6, C20:0, C20:4n‐6, C24:0, C24:1, C22:6n‐3 fatty acids between eggs and larvae after yolk‐sac resorption (P < 0.05). Vitamin α‐ Tocopherol and retinol content increased during embryogenesis, but changes were insignificant in retinol acetate, δ‐Tocopherol, K1, K2 and cholesterol content between eggs and larvae after yolk resorption (P > 0.05).     

Temperature and host plant effects on development and fecundity of Brevicoryne brassicae (L.) (Homoptera: Aphididae)

The development, survival and reproduction of the cabbage aphid, Brevicoryne brassicae (L.) were evaluated at three constant temperatures (20, 25 and 30°C) on cabbage, cauliflower, red cabbage, turnip and radish. The development periods of immature stages ranged from 10.7 d at 20°C to 7.60 d at 30°C for red cabbage. Total percentages of survivorship of immature stages varied from 39.40 and 82.50 within the temperature range of 25–30°C on radish. The average progeny per female was 31.15, 28.95 and 23.77 at 20, 25 and 30°C on cabbage.     

Life‐history traits of Aphanius danfordii (Boulenger, 1890) (Pisces: Cyprinodontidae), endemic to Kızılırmak Basin (Turkey)

The life‐history traits of Aphanius danfordii in Hirfanl? Reservoir were studied on the basis of 2252 specimens caught between April 2008 and April 2009. Maximum age was determined as five years for both sexes. The overall sex ratio of males to females was 1 : 1.21; however, this ratio varied by age and season. Mean total length at age data derived from scale readings were used to estimate growth. The von Bertalanffy growth parameters were: L_∞ = 126.63 mm, K = ?0.09, t₀ = 2.35 for females; and L_∞ = 61.2 mm, K = ?0.19, t₀ = 2.76 for males. The gonadosomatic index (GSI) values indicated spawning to be from May to September. Absolute fecundity varied from a minimum of 143 eggs for age one to a maximum of 698 eggs for age five. Relationships between fecundity–length and fecundity–weight were described by the equations: F = 0.0002 TL^3.3222 and F = 36.032 W^1.0053, respectively. The equation of the relation between absolute fecundity and age was F = 25.372 t^1.2343.     

Length–weight relationships of freshwater fishes from the western part of Anatolia,Turkey

Length–weight relationships were calculated for nine freshwater fish species belonging to two families using 1020 specimens from 15 water sources in the western part of Anatolia, Turkey. This study is the first reference on length–parameters for these species, eight of which are endemic, and with new maximum length records for three of the species.     

ICAM1 K469E and E-selectin S128R polymorphisms could predispose to increased autoantibody production and TSH suppression in Graves’ disease

The etiopathogenesis of Graves’ disease (GD) has not been clearly elucidated although the role of chronical inflammation and endothelial dysfunction has been established. Adhesion molecules such as intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), and E-selectin are secreted from vascular endothelium and promote accummulation of leukocytes in damaged endothelial areas. This study examined the possible association of ICAM1 (G241R and K469E), VCAM1 (T-1591C and T-833C), and E-selectin (S128R) single nucleotide polymorphisms (SNPs) with the occurence of GD. ICAM1 (G241R and K469E), VCAM1 (T-1591C and T-833C), and E-selectin (S128R) SNPs in DNA from peripheral blood leukocytes of 171 patients with GD and 259 healthy controls were investigated by real-time PCR combined with melting curve analysis using fluorescence-labeled hybridization probes. We did not find significant differences in the distributions of studied polymorphisms, nor in the haplotype frequencies between patients with GD and healthy control. However, the anti-TPO levels in E-selectin 128R allele carrying subjects (SR + RR) were higher than S128S genotype (p < 0.05). In addition, the decline of TSH levels was more prominent in ICAM1 469 E carrying subjects (KE + EE) in comparison with wild homozygotes (p < 0.05). Although there is not assosiation between ICAM1 (G241R and K469E), VCAM1 (T-1591C and T-833C), and E-selectin (S128R) SNPs and susceptibility to GD, higher anti-TPO in E-selectin 128 SR + RR, and lower TSH in ICAM1 469 KE + EE subjects suspect that these genotypes are prone to increased antithyroid autoantibody production with more accentuated TSH suppression in GD. Further studies with a larger cohort, analyzing other polymorphisms in ICAM, VCAM1 and E-selectin genes are necessary to support our observations.     

Environmental Regulation of Mitochondria-Rich Cells in Chalcalburnus tarichi (Pallas, 1811) During Reproductive Migration

Chalcalburnus tarichi is an anadromous cyprinid fish that has adapted to extreme conditions (salinity 22 ‰, pH 9.8 and alkalinity 153 mEq × l^?1) in Lake Van in eastern Turkey. Changes in immunoreactivity of Na⁺/K⁺-ATPase in gill tissue and osmolarity and ion levels in plasma were investigated in C. tarichi during reproductive migration. Physicochemical characteristics and ion levels in Lake Van were high compared freshwater. Plasma osmolality and plasma ion concentrations ([Na⁺], [K⁺] and [Cl^?]) increased after transfer from freshwater to Lake Van. The mitochondria-rich (MR) cells of the gill were stained in both filament and lamellar epithelia of C. tarichi by immunocytochemistry with a specific antiserum for Na⁺/K⁺-ATPase in river fish samples. Density and area of MR cells were decreased in lake-adapted fishes. These results indicated that freshwater acclimation capacity is correlated with the size and distribution of MR cells in C. tarichi, in contrast to many teleost fishes.