Kinetics of Na(+) transport in necturus proximal tubule

The dependence of proximal tubular sodium and fluid readsorption on the Na(+) concentration of the luminal and peritubular fluid was studied in the perfused necturus kidney. Fluid droplets, separated by oil from the tubular contents and identical in composition to the vascular perfusate, were introduced into proximal tubules, reaspirated, and analyzed for Na(+) and [(14)C]mannitol. In addition, fluid transport was measured in short-circuited fluid samples by observing the rate of change in length of the split droplets in the tubular lumen. Both reabsorptive fluid and calculated Na fluxes were simple, storable functions of the perfusate Na(+) concentration (K(m) = 35-39 mM/liter, V(max) = 1.37 control value). Intracellular Na(+), determined by tissue analysis, and open-circuit transepithelial electrical potential differences were also saturable functions of extracellular Na(+). In contrast, net reabsorptive fluid and Na(+) fluxes were linearly dependent on intracellular Na(+) and showed no saturation, even at sharply elevated cellular sodium concentrations. These concentrations were achieved by addition of amphotericin B to the luminal perfusate, a maneuver which increased the rate of Na(+) entry into the tubule cells and caused a proportionate rise in net Na(+) flux. It is concluded that active peritubular sodium transport in proximal tubule cells of necturus is normally unsaturated and remains so even after amphotericin-induced enhancement of luminal Na(+) entry. Transepithelial movement of NaCl may be described by a model with a saturable luminal entry step of Na(+) or NaCl into the cell and a second, unsaturated active transport step of Na(+) across the peritubular cell boundary.     

Cuticular Membrane Fine Structure of Nicotiana tabacum L. Leaves

The cuticular membrane (CM) ofNicotiana tabacumL., includingthe cellin wall (CW), was examined to gain more informationabout the nature and chemical constitution of its fine structurefor possible inclusion in a model system, as recent literaturequestions its function as a major water permeability barrier.Different preparation techniques were used and the results evaluatedto select a method for future studies on tobacco leaf cuticles.Fixation with OsO₄included in the primary fixative, either asa vapour or in combination with other agents, followed by OsO₄aspost-fixative, gave good contrast of the CM. The lamellar structureof the tobacco cuticle proper (CP) was revealed by contrastingwith uranyl acetate and lead citrate. The fine lamellar structureof the CP was very clearly contrasted when KMnO₄was includedin the primary fixative. This was interpreted as indicatingthe tobacco CP to be polar. The reticulate fibrillar patternof the tobacco cuticular layer (CL) containing polysaccharideswas well contrasted when either OsO₄or paraformaldehyde wereincluded in the primary fixative. Cold fixation with glutaraldehydeand dimethyl sulphoxide and post-fixation with OsO₄revealedelectron-opaque material in the outer cutinized, irregularlyoutlined, region of the CW. These ultrahistochemical reactionsare discussed in relation to the known chemical compositionand possible water permeability of the CM. Cuticular fine structure; cuticular transpiration; Nicotiana tabacumL.     

Distribution of individual members of the mosquito Anopheles maculipennis complex in Germany identified by newly developed real‐time PCR assays

Owing to their role as vectors of malaria parasites, species of the Anopheles maculipennis complex (Diptera: Culicidae) Meigen were intensively studied in the past, but with the disappearance of malaria in Germany in the middle of the last century, the interest in this field of research declined. A comprehensive ecological analysis of the current species distribution for Germany is lacking. Between 2010 and 2013, a total of 1445 mosquitoes of the An. maculipennis complex were collected at 72 different sites in Germany. The samples comprise 722 single individuals as well as 723 individuals in 90 pools of up to 25 mosquitoes. All samples were analysed with newly developed species‐specific qPCR assays for the identification of the four German species using nucleotide differences within the internal transcribed spacer 2 (ITS2) ribosomal DNA. All gathered data were used for species distribution modelling. The overall prevalence of An. messeae s.l. was highest with 98.89% of all pools; An. daciae with 6.93% of all individuals and An. messeae s.s. with 69.53%. The prevalence of the other two species was relatively low: An. maculipennis s.s. with 13.30% of all individuals (6.67% of all pools) and An. atroparvus with 1.80% of all individuals (1.11% of all pools).     

Colonization and Immunomodulation by Lactobacillus reuteri ATCC 55730 in the Human Gastrointestinal Tract

Lactobacillus reuteri ATCC 55730 is a probiotic (health-promoting) bacterium widely used as a dietary supplement. This study was designed to examine local colonization of the human gastrointestinal mucosa after dietary supplementation with L. reuteri ATCC 55730 and to determine subsequent immune responses at the colonized sites. In this open clinical investigation, 10 healthy volunteers and 9 volunteers with ileostomy underwent gastroscopy or ileoscopy and biopsy samples were taken from the stomach, duodenum, or ileum before and after supplementation with 4 × 10⁸ CFU of live L. reuteri ATCC 55730 lactobacilli per day for 28 days. Biopsy specimen colonization was analyzed using fluorescence in situ hybridization with a molecular beacon probe, and immune cell populations were determined by immunostaining. Endogenous L. reuteri was detected in the stomach of 1 subject and the duodenum of 3 subjects (out of 10 subjects). After L. reuteri ATCC 55730 supplementation, the stomachs of 8 and the duodenums of all 10 subjects were colonized. Three ileostomy subjects (of six tested) had endogenous L. reuteri at baseline, while all six displayed colonization after L. reuteri supplementation. Gastric mucosal histiocyte numbers were reduced and duodenal B-lymphocyte numbers were increased by L. reuteri ATCC 55730 administration. Furthermore, L. reuteri administration induced a significantly higher amount of CD4-positive T-lymphocytes in the ileal epithelium. Dietary supplementation with the probiotic L. reuteri ATCC 55730 induces significant colonization of the stomach, duodenum, and ileum of healthy humans, and this is associated with significant alterations of the immune response in the gastrointestinal mucosa. These responses may be key components of a mechanism by which L. reuteri ATCC 55730 exerts its well-documented probiotic effects in humans.     

Internal eliminated sequences interrupting the Oxytricha 81 locus: allelic divergence, conservation, conversions, and possible transposon origins

Internal eliminated sequences (IESs) often interrupt ciliate genes in the silent germline nucleus but are exactly excised and eliminated from the developing somatic nucleus from which genes are then expressed. Some long IESs are transposons, supporting the hypothesis that short IESs are ancient transposon relics. In light of that hypothesis and to explore the evolutionary history of a collection of IESs, we have compared various alleles of a particular locus (the 81 locus) of the ciliated protozoa Oxytricha trifallax and O. fallax. Three short IESs that interrupt two genes of the locus are found in alleles from both species, and thus must be relatively ancient, consistent with the hypothesis that short IESs are transposon relics. In contrast, TBE1 transposon interruptions of the locus are allele-specific and probably the results of recent transpositions. These IESs (and the TBE1s) are precisely excised from the DNA of the developing somatic macronucleus. Each IES interrupts a highly conserved sequence. A few nucleotides at the ends of each IES are also conserved, suggesting that they interact critically with IES excision machinery. However, most IES nucleotide positions have evolved at high rates, showing little or no selective constraint for function. Nonetheless, the length of each IES has been maintained (+/- 3 bp). While one IES is approximately 33 bp long, three other IESs have very similar sizes, approximately 70 bp long. Two IESs are surrounded by direct repeats of the sequence TTCTT. No other sequence similarities were found between any of the four IESs. However, the ends of one IES do match the inverted terminal repeat consensus sequence of the "TA" IESs of Paramecium. Three O. trifallax alleles appear to have been recipients in recent conversion events that could have been provoked by double-strand breaks associated with IES ends subsequent to IES transposition. Our findings support the hypothesis that short IESs evolved from ancient transposons that have lost most of their sequences, except those necessary for precise excision during macronuclear development.      

Biodiversity and ecology of epilithic diatoms in the Agnéby River,Ivory Coast

The ecology and taxonomy of the epilithic diatom flora of the Agnéby River, Ivory Coast were studied in 2012. Ten sites were investigated and diatoms were sampled on glass slides immersed for a period of 30 days during the wet and dry seasons. Physico-chemical parameters were measured at each site while sampling diatoms. Five taxa were largely dominant: Planothidium comperei CE Wetzel, N’Guessan and Tison-Rosebery, Eolimna minima (Grunow) Lange-Bertalot, Planothidium piaficum (JR Carter and Denny) CE Wetzel and Ector, Cocconeis schroederi Foged and Cocconeis scutellum var. parva (Grunow in Van Heurck) Cleve. Electrical conductivity, temperature, dissolved oxygen, nitrite and phosphorus were found to influence the distribution of taxa.     

Mating disruption in Agrotis segetum monitored by harmonic radar

The long-range, pheromone-mediated, flight behaviour of male moths under natural and mating disruption conditions was monitored by means of harmonic radar. Individual male turnip moths, Agrotis segetum (Denis & Schiffermüller) (Lepidoptera: Noctuidae), tagged with radar transponders, were released and tracked in plots with or without disruptive doses of sex pheromone. In addition, male attraction to pheromone-baited traps and mating of calling females in treated and untreated plots was investigated. High doses of a four-component pheromone blend reduced trap catch by 79% and mating of females by 62% when compared with control plots in pre-radar experiments. Surprisingly, this effect was not associated with any pronounced differences in flight behaviour of males between a treatment and a control plot as revealed by harmonic radar recordings. In total, 20 flight tracks from a control plot and 22 flight tracks from a treatment plot were analysed. Moths could be followed for up to 77 min, corresponding to a track length of 7350 m. Mean ground speed ranged from 0.7 m s^–1 to 5.4 m s^–1. There was a strong trend (P = 0.06) for a greater number of male orientations to traps from downwind in the control field compared to the treatment field. Many flight tracks were fragmented due to radar shadow. Advantages and constraints using harmonic radar to study the pheromone-mediated flight behaviour of nocturnal moths are discussed.     

Dendrite Growth—Microstructure—Stress—Interrelations in Garnet Solid-State Electrolyte

This study illustrates how the microstructure of garnet solid-state electrolytes (SSE) affects the stress-state and dendrite growth. Tantalum-doped lithium lanthanum zirconium oxide (LLZTO, Li_6.4La₃Zr_1.4Ta_0.6O₁₂) is synthesized by powder processing and sintering (AS), or with the incorporation of intermediate-stage high-energy milling (M). The M compact displays higher density (91.5% vs 82.5% of theoretical), and per quantitative stereology, lower average grain size (5.4 ± 2.6 vs 21.3 ± 11.1 µm) and lower AFM-derived RMS surface roughness contacting the Li metal (45 vs 161 nm). These differences enable symmetric M cells to electrochemically cycle at constant capacity (0.1 mAh cm⁻²) with enhanced critical current density (CCD) of 1.4 versus 0.3 mA cm⁻². It is demonstrated that LLZTO grain size distribution and internal porosity critically affect electrical short-circuit failure, indicating the importance of electronic properties. Lithium dendrites propagate intergranularly through regions where LLZTO grains are smaller than the bulk average (7.4 ± 3.8 µm for AS in a symmetric cell, 3.1 ± 1.4 µm for M in a half-cell). Metal also accumulates in the otherwise empty pores of the sintered compact present along the dendrite path. Mechanistic modeling indicates that reaction and stress heterogeneities are interrelated, leading to current focusing and preferential plating at grain boundaries.     

Benzoxazinone — kanamycin derivative: a new fluorescent probe for flow cytometry analysis of bacteria (Agrobacterium tumefaciens)

Abstract A new polycation fluorescent dye (BVC-kinamycin-conjugate) has been synthesized and used to detect alive bacteria by flow cytometry. This fluorescent chromophore has the noteworthy property of being excited at the same wavelength as fluoresceinylated conjugates (488 nm) and to show a much longer emission wavelength (616 nm) than fluoresceinylated derivates (520 nm); furthermore its fluorescence intensity is not quenched at low pH in contrast with fluorescein. In such conditions, bacteria can easily be detected with cytofluorimeter equipped with a single excitation wavelength beam. The binding of fluoresceinylated lectins and antibodies onto a strain of Agrobacterium tumefaciens has been studied by this method.