Clocks for sex: loss of circadian rhythms in ants after mating?

This paper describes experiments on the locomotor activity rhythm of queens of the ant species Camponotus compressus, which were performed to investigate the consequences of mating on circadian clocks. Locomotor activity rhythm of virgin and mated queens was monitored individually under constant conditions of the laboratory. The locomotor activity rhythm of virgin queens entrained to a 24 h (12:12 h) laboratory light/dark (LD) cycle and free-ran under constant dim red light (RR) with a free-running period () of approximately 24 h. The locomotor activity of the mated queens on the other hand was arrhythmic during the period when they were laying eggs, and robust rhythmicity appeared soon after the egg-laying phase was over. The of the locomotor activity rhythm of mated queens was significantly greater than that of virgin queens. These results are contrary to the commonly held belief that the role of circadian clocks in ant queens ceases after mating flights, thus suggesting that circadian clocks of ant queens are adaptively plastic and display activity patterns, perhaps depending on their physiological state and tasks in the colony.     

Pinealectomy shortens resynchronisation times of house sparrow (Passer domesticus) circadian rhythms

In many birds periodic melatonin secretion by the pineal organ is essential for the high-amplitude self-sustained output of the circadian pacemaker, and thus for the persistence of rhythmicity in 24 h oscillations controlled by it. The elimination of the pineal melatonin rhythm, or a reduction of its amplitude, renders the circadian pacemaker a less self-sustained, often highly damped, oscillatory system. A reduction in the degree of self-sustainment of a rhythm should not only increase its range of entrainment but also shorten the resynchronization times following phase-shifts of the zeitgeber. This hypothesis has not yet been directly tested. We therefore carried out the present study in which house sparrows (Passer domesticus) were subjected to both 6-h advance and 6-h delay phase-shifts of the light–dark cycle before and after the pinealectomy, and the rhythms in locomotion and feeding were recorded. The results indicate that following the delay, but not the advance, phase shift, resynchronization times were significantly shorter after pinealectomy. The dependence of resynchronization times on the presence or absence of the pineal organ is not only of theoretical interest but might also be of functional significance in the natural life of birds. A reduction or elimination of the amplitude of the melatonin secretion rhythm by the pineal organ might be responsible for faster adjustment to changes in zeitgeber conditions in nature. Professor Dr E. Gwinner died on 07 September 2004.     

Chlorinated hydrocarbon contaminants in blood of black and turkey vultures from Savannah River Site,South Carolina,USA

Blood of adult and juvenile black and turkey vultures in the Savannah River Site of South Carolina, USA was analyzed for the presence of 2,3,7,8-chlorine substituted polychlorinated dibenzo-p-dioxins (2,3,7,8-PCDDs), dibenzofurans (2,3,7,8-PCDFs), -dioxin-like and -di-ortho polychlorinated biphenyls. Concentration ranges of 2,3,7,8-PCDD/DFs in blood of black and turkey vultures were 14.2-34.6 and 8.7-56.2 pg/ml wet wt., respectively. Dioxin-like PCBs were in the ranges of 815-4627 and 753-3611 pg/ml wet wt. respectively, in black and turkey vultures. Considerable concentrations of two congeners of di-ortho PCBs were noticed in the ranges of 1415-10325 and 663-7500 pg/ml respectively, in black and turkey vultures. Comparatively, greater toxic equivalency (TEQ) were observed in blood of turkey vultures with the ranges of 3.2-20, whereas black vulture contained 1.8-8.4 pgTEQ/ml wet wt. basis. The species-specific accumulation profiles of PCDD/DFs and dioxin-like PCBs may reflect the different feeding habits, ecology, metabolic capacity and migratory movements of these two scavenging species.     

Assessment of the effect of the toxicity of a textile dye on Nostoc muscorum ISU, a diazotrophic cyanobacterium

The impact of graded concentrations (5, 10, 15 and 20 mg dm(-3) of acid mordant Metomega Chrome Orange GL, a common dye used in woollen, carpet and textile industries, was studied on protein and pigment content and photosynthetic oxygen evolution in a diazotrophic cyanobacterium Nostoc muscorum. The lower concentration of 5 mg dm(-3) showed a negligible effect on protein and pigment content and photosynthetic oxygen evolution, whereas at higher concentrations a drastic decrease in the above parameters was observed. The highest concentration of 20 mg dm(-3) resulted in a decrease of protein, chlorophyll a, phycocyanin and carotenoid content by 72, 76, 54 and 17% of the control, respectively. Photosynthetic oxygen evolution also decreased by 92% of the control at this concentration of the dye.     

Treatment of distillery spent-wash by ozonation and biodegradation: significance of pH reduction and inorganic carbon removal before ozonation.

This study is aimed at exploring strategies for mineralization of refractory compounds in distillery effluent by anaerobic biodegradation/ozonation/aerobic biodegradation. Treatment of distillery spent-wash used in this research by anaerobic-aerobic biodegradation resulted in overall COD removal of 70.8%. Ozonation of the anaerobically treated distillery spent-wash was carried out as-is (phase I experiments) and after pH reduction and removal of inorganic carbon (phase II experiments). Introduction of the ozonation step resulted in an increase in overall chemical oxygen demand (COD) removal, with the highest COD removals of greater than 95% obtained when an ozone dose of approximately 5.3 mg ozone absorbed/mg initial total organic carbon was used. The COD removal during phase II experiments was slightly superior compared with phase I experiments at similar ozone doses. Moreover, efficiency of ozone absorption from the gas phase into distillery spent-wash aliquots was considerably enhanced during phase II experiments.     

A study for evaluation of contaminant transport characteristics through fine-grained soil.

Transport of soluble toxic substances through porous media lead to some significant geoenvironmental problems, for example, leachate migration from municipal and industrial solid waste resulting from unregulated disposal. Advection, dispersion, diffusion, and decay are reported to be the principal mechanisms in such phenomena. Geotechnical properties of the soil also play a significant role in this deterioration. In the present study, laboratory tests were conducted to formulate an appropriate method for assessment of migration of metal ions, such as nickel, through the soil. Relevant kinetic and process parameters, such as aquifer data, surface area, dielectric constant, pH of zero point charge (pHzpc), and permeability were also studied. One-dimensional mathematical modeling was used to describe the dynamics of the process. The present investigation was carried out at an ash pond site of a thermal power plant situated in West Bengal, India.     

The effects of dieldrin, dimethoate and permethrin on Tetrahymena pyriformis

The effects of three insecticides, dieldrin, dimethoate and permethrin, on the growth of a holotrichous ciliate, Tetrahymena pyriformis, were studied for 5 days. The ciliate was very sensitive to dieldrin and dimethoate. Both these insecticides produced approximately 81% and 84% inhibition of growth within two days. Dieldrin caused rounding of cells, while dimethoate induced cell lysis. Dimethoate also triggered a general mucocyst discharge. Of the three insecticides, permethrin was the least toxic and induced no morphological alterations.