Production of a thermostable alkali-tolerant xylanase from Bacillus circulans AB 16 grown on wheat straw

Bacillus circulans AB 16 was able to produce 50 IU/ml of xylanase, with negligible cellulase activity when grown on untreated wheat straw. The pH optimum of the crude enzyme was 6–7 with a temperature optimum of 80 C. The enzyme showed high pH and thermal stability retaining 100% activity at 60 C, pH 8 and 9 after 2.5 h of incubation. The residual activity at 70 C after 2.5 h was 62% and 45% at pH 8 and 9, respectively. At 75 C only 22.2% activity remained at pH 8 after 1 h incubation. Since Kraft pulp is alkaline this enzyme could be used for prebleaching of pulp at temperatures up to 70 C without pH adjustment.     

Molecular screening and fetal diagnosis of β-thalassemia in the Italian population

Summary This paper reports our experience of molecular screening and fetal diagnosis of -thalassemia in 457 at risk couples of Italian descent. Molecular screening was carried out by dot blot analysis on amplified DNA with oligonucleotide probes complementary to the eight most common mutations in Italians [39 (CT); 6 (-A); ⁺-87 (CG); ⁺ IVSI nt 110 (GA); IVSI nt 1 (GA); ⁺ IVSI nt 6 (TC); IVSII nt 1 (GA); ⁺ IVSII nt 745 (CG)]. By using this approach, we have been able to define the mutation in 92.8% of cases. The rest (all but four) were defined by direct sequencing and this led to the detection of nine rare mutations [76 (-C); ⁺ IVSI nt 5 (GA); ⁺ IVSI nt 5 (GC); ⁺ IVSI -1 (cod 30) (GC); ⁺-87 (CT), -290 bp del.; ⁺-101 (CT)], and to the characterization of a novel mutation consisting of the deletion of the G at the invariant AG of the IVSII splice acceptor site of the -globin gene ( IVSII nt 850-1 bp). In the remaining four cases, the -globin gene showed entirely normal sequences and the -globin gene cluster was intact, as indicated by Southern blot analysis. Fetal diagnosis was carried out by dot blot analysis with the oligonucleotide probes defined in the parents. The procedure is simple and reliable, and the results can be obtained within 1 week of sampling. No misdiagnosis has so far occurred. The results indicate that fetal diagnosis of -thalassemia by DNA analysis may be obtained in practically all cases (even in a population showing marked heterogeneity of -thalassemia) by the combination of dot blot analysis for detecting common mutations, and direct sequencing for defining those that are uncommon.     

Requirement for nonprotonated drug molecules in the direct lethal action of miconazole against Candida albicans

At 10^–5 M, miconazole (MCZ) can exert a direct physicochemical cell-damaging lethal action against logarithmic phase yeasts of Candida albicans. The imidazole moiety of MCZ has a pKa 6.5. Thus, in media of pH >6.5 most drug molecules are nonprotonated (MCZ). Conversely, at pH < 6.5 the majority are protonated and carry a positive charge (MCZH⁺). Our earlier work suggesting that MCZ is required for direct lethal action was tested further. In support of such a requirement, we established a minimal lethal concentration of MCZ (i.e. 5×10^–6 M) that was relatively independent of pH, MCZ concentration, and MCZMCZH⁺ ratio.     

Slow growth phenotype - A possible approach to improved plasmid maintenance in Saccharomyces cerevisiae

Summary Transformation-induced slow growth phenotype (SGP) in yeast is repressed in the presence of 2m plasmids. A full 2m-sequence-based recombinant plasmid (pJB502) was found to be more stable in a 2m-free- [cir] strain of Saccharomyces cerevisiae than in a cir⁺ strain. This could not be attributed to differences in growth rate calculated from kinetic analysis of plasmid loss, but transformed [cir] isolates, which had lost the recombinant plasmid, exhibited varying degrees of SGP in batch culture. One of these isolates was outcompeted in chemostat culture by the recombinant-plasmid-containing strain, suggesting that improved plasmid maintenance can result from SGP in cir hosts.     

The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

Geochemical controls for Al, Fe, Mn, Cd, Cu, Pb, and Zn during experimental acidification and recovery of Little Rock Lake, WI, USA

Concentrations of Al, Fe, Mn, Cd, Cu, Pb, and Zn were measured in thereference and treatment basins of Little Rock Lake (Vilas County, Wisconsin), alow-alkalinity, seepage system (pH 6.1, alkalinity25eq/L) during six years of a whole-basinacidificationand the first four years of the lake's recovery. The treatment basin wasacidified with H₂SO₄ in three two-year steps to pH5.6, 5.1, and 4.7. By the end of year 4 of recovery, treatmentbasin pH increased to 5.3 as a result of internal alkalinity generation.During acidification, dissolved Mn and Fe (0.4mpore-size filters) increased at pH 5.6; dissolved Al, Cd, and Zn becameelevated at pH 5.1; and dissolved Pb at pH 4.7. Dissolved Cu remainedsimilar in both basins to pH 4.7. Al, Fe and Mn levels declinedsignificantly during the recovery period, approaching values at pH 5.3intermediate between the concentrations at pH 5.6 and 5.1 during acidification.Dissolved Al and Fe in the reference basin were near the equilibrium levels forsolubility of gibbsite (Al(OH)₃) and amorphousFe(OH)₃(s).The acidified basin was undersaturated relative to gibbsite, and dissolved Alwas limited by pH disequilibrium between the water column and sediments andpossibly by Al-DOC precipitation. Dissolved Fe apparently was controlled bysolubility of amorphous Fe(OH)₃(s) and Fe-DOC precipitation.Dissolved Mn levels in both basins were consistent with manganite[-MnOOH(s)] solubility. Elevated levels of Cd, Pb, and Zn in thetreatment basin during acidification probably resulted from less efficientscavenging of atmospherically-deposited Cd, Pb, and Zn by settling particles.     

Altered utilization patterns of young and old soil C by microorganisms caused by temperature shifts and N additions

To determine if changes in microbial community composition and metabolic capacity alter decomposition patterns of young and old soil carbon pools, we incubated soils under conditions of varying temperature, N-availability, and water content. We used a soil from a pineapple plantation (CAM; ¹³C litter = –14.1) that had previously been under tropical forest (C3; ¹³C soil carbon = –26.5). Forest derived carbon represented 'old' carbon and plantation inputs represented 'new' carbon. In order to differentiate utilization of young (< 14 years) and old (> 14 years) soil carbon, we measured the ¹³C of respired CO₂ and microbial phospholipid fatty acids (PLFAs) during a 103 day laboratory incubation. We determined community composition (PLFA and bacterial intergenic transcribed spacer (ITS) analysis) in addition to carbon degrading and nutrient releasing enzyme activities. We observed that greater quantities of older carbon were respired at higher temperatures (20 and 35°C) compared to the lower temperature (5°C). This effect could be explained by changes in microbial community composition and accompanying changes in enzyme activities that affect C degradation. Nitrogen addition stimulated the utilization of older soil carbon, possibly due to greater peroxidase activity, but microbial community composition was unaffected by this treatment. Increasing soil moisture had no effect on the utilization of older SOM, but enzyme activity typically declined. Increased oxidative enzyme activities in response to elevated temperature and nitrogen additions point to a plausible mechanism for alterations in C resource utilization patterns.     

Substitutions of the Conserved Thr42 Increased the Roles of the ε-Subunit of Maize CF1 as CF1 Inhibitor and Proton Gate

The conserved residue Thr42 of -subunit of the chloroplast ATP synthase of maize (Zea mays L.) was substituted with Cys, Arg, and Ile, respectively, through site-directed mutagenesis. The over-expressed and refolded -proteins were purified by chromatography on DEAE-cellulose and FPLC on mono-Q column, which were as biologically active (inhibiting Ca²⁺-ATPase activity and blocking proton gate) as the native subunit isolated from chloroplasts. The T42C and T42R showed higher inhibitory activities on the soluble CF₁(–) Ca²⁺-ATPase than the WT. The T42I inhibited the Ca²⁺-ATPase activity of soluble CF₁ and restored photophosphorylation activity of membrane-bound CF₁ deficient in the most efficiently. Far-ultraviolet CD spectra showed that the portions of -helix and -sheet structures of the three mutants were somewhat different from WT. Thus the conserved residue Thr42 may be important for maintaining the structure and function of the -subunit and the basic functions of the -subunit as far as an inhibitor of Ca²⁺-ATPase and the proton gate are related.     

Ultrastruttura della Pars distalis dell'ipofisi di Lacerta s. sicula Raf., nei maschi in attività sessuale ed in quelli castrati

Riassunto Facendo seguito ad uno studio in microscopia ottica sull'ipofisi della Lacerta s. sicula Raf. durante vari periodi dell'anno, gli AA. espongono, per la stessa specie, i dati ultrastrutturali per le cellule adenoipofisarie, di maschi ancora in periodo di attiva spermatogenesi e di accoppiamento, e di altri castrati e sacrificati dopo 3–4 mesi. In base alla localizzazione nella ghiandola ed alle variazioni dopo castrazione, si distinguono cellule del 1 tipo (STH) con granuli rotondeggianti ed uniformi (circa 310 m ), cellule del 2 tipo (gonadotrope) a granuli polimorfi, cellule del 3 tipo (pure gonadotrope) a granuli tondi e piccoli (150–270 m) e a globuli di 700–800 m, e cellule del 4 tipo a granuli piccoli ed uniformi (100–200 m), di dubbio significato. Presentano dati a favore dell'ipotesi che la condensazione del secreto in forma di granuli avvenga nelle cisterne del Golgi. Osservano fenomeni di degenerazioni cellulari ed aspetti di distruzione citoplasmatica con liberazione di granuli negli spazi tra le cellule. Negli animali castrati notano degranulazione e segni di intensa attività delle cellule del 2 e del 3 tipo, oltre alla comparsa di cellule vacuolizzate, per dilatazione del reticolo endoplasmico ruvido.

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The ultrastructure of the pars distalis of the hypophysis in sexually active and castrated males of Lacerta s. sicula Raf

Summary In addition to light microscopic studies on the hypophysis of the lizard, Lacerta s. sicula Raf., during different periods of the year, the authors of this paper explain the ultrastructure of the adenohypophysial cells of normal sexually active male lizards and of castrated lizards. On the basis of the location and the structural variations after castration several hypophysial cell types can be distinguished: Type 1 (STH) with spheroid granules (about 310 m diameter); type 2 with polymorphous glycoprotein granules; type 3 with small round granules (150–270 m diameter) and globules of about 700–800 m diameter (both gonadotropes). A fourth cell type with small uniform granules (diameter about 100–200 m has also been observed; its function is uncertain. A condensation of secretory granules in the Golgi complex and phenomena of cellular degeneration and cytolysis followed by a release of granules into the cellular interstices have been observed. In castrated animals degranulation and signs of an increased activity in the cell types 2 and 3 have been shown. In these animals the cisternae of endoplasmic reticulum become greatly distended.

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Lavoro eseguito con il contributo del Consiglio Nazionale delle Ricerche, Impresa Endocrinologia, e svolto, per le osservazioni, presso il Centro di Studio di Microscopia Elettronica della Facoltà di Scienze dell'Università di Napoli; ringraziamo il Prof. Gianfranco Ghiara per la continua critica costruttiva e il dott. Carlo Taddei per i suggerimenti nelle tecniche di microscopia elettronica.     

Nuclear Overhauser effect investigation on GM1 ganglioside containingN-glycolyl-neuraminic acid (II3Neu5GcGgOse4Cer)

The conformational properties of the oligosaccharide chain of GM1 ganglioside containingN-glycolyl-neuraminic acid, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-were found to fix the relative orientitation of the three saccharides, while the glycosidic linkage of the terminal -Gal-was found to be quite mobile as the -Gal-(1-3)--GalNAc-disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containingN-acetyl-neuraminic acid and neuraminic acid [1].Abbreviations Ganglioside nomenclature is in accordance with Svennerholm [23] and the IUPAC-IUB Recommendations [24] GM3(Neu5Ac) II³Neu5AcLacCer, -Neu5Ac-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM3(Neu5Gc) II³Neu5GcLacCer, -Neu5Gc-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Ac) II³Neu5AcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Gc) II³Neu5GcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu) II³NeuGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu-(2-3)]--Glc-(1-1)-Cer - GD1a IV³Neu5AcII³Neu5AcGgOse₄Cer, -Neu5Ac-(2-3)--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GalNAc-GD1a IV⁴GalNAcIV³Neu5AcII³Neu5AcGgOse₄Cer, -GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - Neu neuraminic acid - Neu5Ac N-acetyl-neuraminic acid - Neu5Gc N-glycolyl-neuraminic acid - Cer ceramide     

A novel PH-CT-COSY methodology for measuring JPH coupling constants in unlabeled nucleic acids. Application to HIV-2 TAR RNA

A quantitative analysis of J_PH scalar couplings in nucleic acids is difficult due to small couplings to phosphorus, the extreme overlap of the sugar protons and the fast relaxation of the spins involved in the magnetization transfer. Here we present a new methodology that relies on heteronuclear Constant Time Correlation Spectroscopy (CT-COSY). The three vicinal ³J_PH3, ³J_PH5 and ³J_PH5 scalar couplings can be obtained by monitoring the intensity decay of the P_i-H3_{i – 1} peak as a function of the constant time T in a 2D correlation map. The advantage of the new method resides in the possibility of measuring the two ³J_PH5 and ³J_PH5 scalar couplings even in the presence of overlapped H5/H5 resonances, since the quantitative information is extracted from the intensity decay of the P-H3 peak. Moreover, the relaxation of the H3 proton is considerably slower than that of the H5/H5 geminal protons and the commonly populated conformations of the phosphate backbone are associated with large ³J_PH3 couplings and relatively small ³J_{PH5 / H5}. These two facts lead to optimal signal-to-noise ratio for the P-H3 correlation compared to the P-H5/H5 correlation.The heteronuclear CT-COSY experiment is suitable for oligonucleotides in the 10–15 kDa molecular mass range and has been applied to the 30mer HIV-2 TAR RNA. The methodology presented here can be used to measure P-H dipolar couplings (D_PH) as well. We will present qualitative results for the measurement of P-H_base and P-H2 dipolar couplings in the HIV-2 TAR RNA and will discuss the reasons that so far precluded the quantification of the D_PHs for the 30mer RNA.     

β-Thalassemia major resulting from a compound heterozygosity for the β-globin gene mutation: further evidence for multiple origin and migration of the thalassemia gene

Summary We describe in a Japanese family -thalassemia resulting from a compound heterozygosity for a -globin gene mutation. One mutation is a C-to-T transition at IVS-2 nucleotide position 654 on the background of Mediterranean haplotype IX. Another mutation is a G-to-A transition at IVS-2 nucleotide position 1, associated with a novel haplotype XL The occurrence of these mutations on various chromosomal backgrounds provides strong evidence for an interplay of gene migration, interallelic gene conversion, and multiple origins of the same mutation.     

The combined effect of high hydrostatic pressure,heat and bacteriocins on inactivation of foodborne pathogens in milk and orange juice

The objective of this study was to combine pressure (345 MPa) with heat (50 C), and bacteriocins (5000 AU/ml sample) for a short time (5 min) for the inactivation of relatively pressure-resistant strains of four foodborne pathogens: Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella in pasteurized milk and orange juice. Without bacteriocin addition, 5.5 log-cycle reduction was obtained for S. aureus 485 in milk whereas more than 8 log-cycle reduction was achieved for all the other strains studied. After storage of samples for 24 h at 4 C, S. aureus 765 also gave positive results on selective media, where no growth was observed for all the other micro-organisms assayed. Incubation of the same pressurized samples at 37 C for 48 h showed growth of L. monocytogenes strains in addition to S. aureus strains, where still no growth was observed for E. coli O157:H7 and Salmonella strains in their respective selective media. For orange juice samples, more than 8 log-cycle reduction was achieved for all the bacterial species studied. No growth was seen for these species on their respective selective media agar plates after storage at 4 C for 24 h and at 37 C for 48 h. When a bacteriocin-based biopreservative (BP₁) was combined with pressurization, more than 8 log-cycle reduction in cell population of the resistant strains of S. aureus and L. monocytogenes were achieved in milk after pressurization. Milk samples were stored at 25 C up to 30 days to test the effect of treatment and samples showed no growth whereas all the controls were positive.     

Measurement of three-bond coupling constants in the osmoregulated periplasmic glucan of Burkholderia solanacearum

Summary The cyclic osmoregulated periplasmic glucan produced by Burkholderia solanacearum contains 13 glucose units, all -(1–2) linked except for one -(1–6) linkage. We report here the measurement of the ³J(C1-H2) and ³J(H1-C2) coupling constants, characterizing the glycosidic linkages, through the use of a ¹³C/¹²C double half-filtered NOESY experiment. The values obtained give information about the (, ) angles of the different linkages. The results presented form an important step towards a detailed experimental model of the cyclic glucan, which might allow us to clarify its biological role and establish whether the cavity of these molecules is compatible with the capability of complexing host molecular signals.     

Enhanced acetyl esterase production by Fusarium oxysporum

Production of acetyl esterase (EC 3.1.1.6) by Fusarium oxysporum strain F3 was enhanced by optimization of growth conditions. Under optimal conditions, activities as high as 0.89U/ml of culture medium were obtained. The culture filtrate was equally active on p-nitrophenyl acetate and acetylxylan. The enzyme produced 71% deacetylation of acetylxylan in 2h at 40C. Activity was optimized at pH6.5 and at 55^C. The respective K_m values for p-nitrophenyl acetate and acetylxylan were 0.25mM and 1.05% (w/v) and the V_m values were 0.65 and 0.43mol acetate/min/mg protein.     

Histoenzymatic characterization of sub-types of Type I fibres in fast muscles of rats

Summary The histochemical activities of succinic dehydrogenase (SDH), myofibrillar Adenosine triphosphatase (ATPase) and alpha glycerophosphate dehydrogenase were studied in serial sections of rat vastus lateralis (red) (RVL), gastrocnemius and diaphragm muscles. Three main fibre-types were distinguished. The Type I fibres of RVL and gastrocnemius muscles fell into two distinct groups: one category-Type IA showed very low ATPase activity. The second category of Type IB fibres displayed moderate ATPase reaction. The Type IA fibres were divisible into two sub-groups when tested for SDH reaction. Type IA₁ fibres possessed a homogenous distribution of diformazan·granules throughout the fibre: Type IA₂ fibres displayed characteristic moth-eaten pattern of diformazan localization. The diaphragm muscle did not show either Type IB or Type IA₂ varieties. The great majority of Type I fibres were sub-type IA₁ in the three fast muscles studied. It is also demonstrated here that an inherent heterogeneity exists between Type I fibres of diaphragm and leg muscles in regard to -GPD localization. This histochemical data emphasizes the fact that subdivision of Type I striated muscle fibres of mammalian animals into two sub-types is only approximate and that a further subcategorization is possible.     

Aufnahme und Metabolisierung Radiculär Angebotenen Indols DurchSinapis Alba

Zusammenfassung Die beschriebenen experimentellen Befunde zeigen, daß die höhere Pflanze grundsätzlich in der Lage ist, organische Verbindungen aus dem Wurzelraum (Rhizosphäre) aufzunehmen, diese als Zwischenprodukte nutzt und in ihr biochemisches Zellgeschehen einschleust. Die organische Substanz (Humus) in natürlichen Standorten bietet somit unter Umständen vielfältige Möglichkeiten des direkten Einflusses organischer Verbindungen auf das Stoffwechselgeschehen der höhere Pflanze. Hier bieten sich eventuell auch Möglichkeiten, die Ausbildung von Ökotypen auf dieser Basis zu deuten.Mixotrophie der höheren Pflanze bedeutet also eine noch stärkere Verflechtung des Bio-Geo-Systems Pflanze-Boden und stellt den klassischen Begriff des Nährhumus unter einen neuen organodynamischen Gesichtspunkt.

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Summary The experimental results described above show, that the higher plant can take up organic compounds from the rhizosphere and utilize them in cell metabolism.Thus another type of chemical interaction between plant and the organic matter of soil is existing, by which the close integration of the bio-geosystem plant and soil can be demonstrated and a modern view of the classical concept of the nutritional functions of humus can be given.

     

Facile synthesis of 2′-substituted lactoses

Isopropylidenation of lactose with 2,2-dimethoxypropane in the presence ofp-toluenesulfonic acid gave two products, which were identified by¹H- and¹³C-NMR as 2,35,63,4-tri-O-isopropylidenelactose dimethyl acetal (1) and its 6-O-(2-methoxy)-isopropyl derivative (2). These products were used for the synthesis of 2-O-methyllactose (7), 2,6-di-O-methyllactose (9) and 2-O-benzyllactose (13).     

Die Richtungen des Nahrungsflusses im Darmtrakt der Kleinzikade Euscelidius variegatus KBM. (Jassidae)

Zusammenfassung Der Verlauf des Nahrungsflusses im Darmtrakt der Kleinzikade Euscelidius variegatus wird nach Verfütterung von farbstoffhaltiger Nährlösung ermittelt. Es wird der Beweis erbracht, daß die aufgenommene Nahrungsmenge in der Filterkammer geteilt wird und die beiden Anteile den Darmtrakt auf zwei verschiedenen Wegen in Richtung Rektalblase passieren. Ein Anteil der aufgenommenen Nährlösung wird über einen Kurzschlußweg in der Filterkammer sowohl über den Filterkammerdarm als auch über die Kryptonephridien direkt in den Enddarm gepumpt, während die in der Magentasche der Filterkammer verbleibenden Nahrungsanteile über einen langen Verdauungsweg zum After gelangen. Hierbei wird der Magentascheninhalt in den Magen gedrückt. Von dort aus passiert er den Mitteldarm und erreicht über den Enddarm den After. Der Kurzschlußweg und der Verdauungsweg können gleichzeitig benutzt werden. Der Kurzschlußweg wird von der Nahrung jedoch in viel kürzerer Zeit durchströmt als der längere Verdauungsweg.

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The directions of the flow of food in the alimentary trad of the leafhopper Euscelidius variegatus KBM. (Jassidae)

Summary The leafhopper Euscelidius variegatus is fed with synthetic food, coloured with 1% Azorubin-S. Its flow in the alimentary tract has been studied. It has been found that the sucked-in food is divided into two parts in the filter chamber, each taking different way in the alimentary tract for its flow. One part of the food is pumped into the hindgut via the short circuit way going through the filter chamber once over the Filterkammerdarm and also over the kryptonephries. That part of the food, which remains in the pocket of the filter chamber takes the long digestion way to the anus over stomach, midgut and hindgut. Both the ways could be used at the same time. But the food takes much shorter time for its passage through the short circuit way as compared to the time needed for the long digestion way.

     

13Cα and 13Cβ chemical shifts as a tool to delineate β-hairpin structures in peptides

Unravelling the factors that contribute to the formation and the stability of -sheet structure in peptides is a subject of great current interest. A -hairpin, the smallest -sheet motif, consists of two antiparallel hydrogen-bonded -strands linked by a loop region. We have performed a statistical analysis on protein -hairpins showing that the most abundant types of -hairpins, 2:2, 3:5 and 4:4, have characteristic patterns of ¹³C and ¹³C conformational shifts, as expected on the basis of their and angles. This fact strongly supports the potential value of ¹³C and ¹³C conformational shifts as a means to identify -hairpin motifs in peptides. Their usefulness was confirmed by analysing the patterns of ¹³C and ¹³C conformational shifts in 13 short peptides, 10–15 residues long, that adopt -hairpin structures in aqueous solution. Furthermore, we have investigated their potential as a method to quantify -hairpin populations in peptides.