Interactions of Photobleaching and Inorganic Nutrients in Determining Bacterial Growth on Colored Dissolved Organic Carbon

Abstract Bacteria are key organisms in the processing of dissolved organic carbon (DOC) in aquatic ecosystems. Their growth depends on both organic substrates and inorganic nutrients. The importance of allochthonous DOC, usually highly colored, as bacterial substrate can be modified by photobleaching. In this study, we examined how colored DOC (CDOC) photobleaching, and phosphorus (P) and nitrogen (N) availability, affect bacterial growth. Five experiments were conducted, manipulating nutrients (P and N) and sunlight exposure. In almost every case, nutrient additions had a significant, positive effect on bacterial abundance, production, and growth efficiency. Sunlight exposure (CDOC photobleaching) had a significant, positive effect on bacterial abundance and growth efficiency. We also found a significant, positive interaction between these two factors. Thus, bacterial use of CDOC was accelerated under sunlight exposure and enhanced P and N concentrations. In addition, the accumulation of cells in sunlight treatments was dependent on nutrient availability. More photobleached substrate was converted into bacterial cells in P- and N-enriched treatments. These results suggest nutrient availability may affect the biologically-mediated fate (new biomass vs respiration) of CDOC.     

Cerebellar neurones: Differentiation and modulation of sensitivity to excitotoxic treatment

The neurite outgrowth and adhesion complex (NOAC), isolated from rabbit sera has been dissociated in its major components by reverse-phase chromatography in HPLC by using a C₁₈ column. SDS-PAGE analisys of the active fractions revealed the presence of three major bands of approximately 100, 70 and 50 kDa. Studies on the biological activity of NOAC were carried out on rat cerebellar granule cells. NOAC-cultured cells exhibit a marked resistance to excitotoxic stimuli carried by glutamate.     

Embracing precarity across species: Muslim ethics and care for stray dogs in Russia

Drawing on ethnographic fieldwork in Saint Petersburg between 2015 and 2016, this article puts work on postsocialist precarity in conversation with scholarship on piety and interspecies care in Muslim contexts to explore how Aliya, a low-income Slavic convert to Islam, responded to social and economic hardships by tending to stray dogs. In doing so, she did not turn away, turn inwards, or turn political in the conventional sense of the word. Instead, she engaged in what I term ‘embracing precarity’, which I define as a response to uncertainty, grounded in Islamic spirituality, ethics, and care. By embracing canine tactility – often in departure from cultural norms concerning stray dogs in Islam and at the risk of deepening her own vulnerability – Aliya embarked on a path towards God with nonhuman others. The emergent relatedness between her and the dogs illustrates how striving for an ethical Muslim life amid uncertainty may open one up to experimentation, improvisation, and becoming with precarious others in a pursuit of a relationship with God and a favourable afterlife.     

Study of DNA films by the CD, X-ray and polarization microscopy techniques.

DNA films with psi +/- CD spectra have been investigated. X-ray analysis has shown the sign of the psi spectra to be independent of the secondary structure of DNA. The appearance of the psi spectra is attended by the formation of a characteristic polygonal texture of the cholesteric type in the DNA film.     

Treatment of renal osteodystrophy with 1,25-dihydroxycholecalciferol.

Nine patients with renal osteodystrophy were tested for 6.5 to 35 months with 1,25-dihydroxycholecalciferol (1,25-DHCC). A close biochemical follow-up was performed during the first 6 months of treatment, including biweekly determinations of serum calcium, phosphorus, magnesium, alkaline phosphatase and creatinine levels. A bone biopsy, radiologic investigations and determinations of plasma levels of immunoreactive parathyroid hormone (IPTH) and intestinal absorption of calcium 47 were performed before and after the 6 months. Although the five patients with osteitis fibrosa showed a significant improvement, the four with predominantly osteomalacic lesions showed no response to treatment. These four had a normal initial plasma iPTH level, higher serum calcium levels than the other five patients, extreme sensitivity to 1,25-DHCC, with frequent episodes of hypercalcemia, and only a slightly increased serum alkaline phosphatase level, which remained unchanged during treatment. All but one of the patients, irrespective of the histologic abnormality, showed a decrease in the uptake of radionuclide by bone after treatment. The renal function of one patient, a man with long-standing stable renal failure who had not undergone dialysis, deteriorated during treatment.     

Three-dimensional structures of bulge-containing DNA fragments.

The three-dimensional structure of a DNA tridecamer d(CGCAGAATTCGCG)2 containing bulged adenine bases was determined by single crystal X-ray diffraction methods, at 120 K, to 2.6 A resolution. The structure is a B-DNA type double helix with a single duplex in the asymmetric unit. One of the bulged adenine bases loops out from the double helix, while the other stacks in to it. This is in contrast to our preliminary finding, which indicated that both adenine bases were looped out. This revised model was confirmed by the use of a covalently bound heavy-atom derivative. The conformation of the looped-out bulge hardly disrupts base stacking interactions of the bases flanking it. This is achieved by the backbone making a "loop-the-loop" curve with the extra adenine flipping over with respect to the other nucleotides in the strand. The looped-out base intercalates into the stacked-in bulge site of a symmetrically related duplex. The looped-out and stacked-in bases form an A.A reversed Hoogsteen base-pair that stacks between the surrounding base-pairs, thus stabilizing both bulges. The double helix is frayed at one end with the two "melted" bases participating in intermolecular interactions. A related structure, of the same tridecamer, after soaking the crystals with proflavin, was determined to 3.2 A resolution. The main features of this B-DNA duplex are basically similar to the native tridecamer but differ in detail especially in the conformation of the bulged-out base. Accommodation of a large perturbation such as that described here with minimal disruption of the double helix shows both the flexibility and resiliency of the DNA molecule.     

Effect of fenamin and haloperidol on conditioned activity of neurons of the motor cortex and striopallidal system

The activity of neurones in the motor cortex, caudate nucleus, putamen and globus pallidus was studied during elaboration of motor conditioned reflexes to time in rabbits, treated with 1-amphetamine and haloperidol. Mechanisms of reproduction of cells trace activity in the reflex to time at the omission of trials, reacted to 1-amphetamine by increasing the intensity of reactions in the motor cortex and inactivation in putamen cells. The curve of dynamics of intensity changes of trace discharges in the course of a series of trials omissions remained unaltered only in motor cortex; in the other structures it significantly differed from the norm of intact animals. Haloperidol depressed the mechanisms of reproduction of trace reactions of the globus pallidus cells, and made them almost fully inactive in the motor cortex; the putamen neurones reacted to haloperidol by an increase of trace reactions intensity. Against the background of the animal chronic 1-amphetamine intoxication, haloperidol normalized the dynamics and intensity of trace activity. "Therapeutic" effect of haloperidol was most distinctly expressed in the motor cortex and putamen cells, less--in the caudate nucleus and was completely absent in the globus pallidus.     

Population dynamics ofTelenomus fariai (Hymenoptera: Scelionidae), a parasite of Chagas' disease vectors IX. Larval competition and population size regulation under laboratory conditions

A series of experiments were carried out with the endophagous egg parasite Telenomus fariai on its host Triatoma phyllosoma pallidipennis to determine the possible role of intraspecific competition by the parasite progeny in population regulation of the parasite. Eight parasite densities (1, 3, 5, 10, 20, 30, 40, and 50 individuals per vial) were used, and the design of sequentially sacrificed replicates applied. Survivorship curves for each density indicated smaller number of progeny per host at higher densities, and the shapes of the curves suggested a relatively early mortality process.Morris' linear regression technique for determining within-generation density-dependence was used, and the results showed that only larval mortality could be identified as density dependent. The same technique applied within the larval stage proved that only mortality of larvae in their second, third, and fourth day of development were responsible for population regulation. The applicability of the technique, as well as the relevance of the results for natural population, is discussed.     

Purpura associated with hypergammaglobulinemia,renal tubular acidosis and osteomalacia.

Two patients with hyperglobulinemia associated with purpura were studied. One had features of Sjögren''s syndrome, while the other appeared to have a primary condition -- "chronic benign purpura". Both patients also had renal tubular acidosis, osteomalacia and renal calculi, with disturbed calcium metabolism and acid-base balance. Autoantibodies were detected in the serum of both patients, and mononuclear cell infiltrates were noted in skin and kidney biopsies from both.