The influence of environmental factors on dormancy and duration of egg development in Metrioptera roeseli (Orthoptera: Tettigoniidae)

Summary Developing eggs of Metrioptera roeseli HGB. have an obligate embryonic diapause in stage 23 and a facultative initial diapause in stage 4. Initial diapause is lacking when the ovipositing females are kept at long day photoperiod (LD 16/8), but is induced at LD 14/10 and LD 8/16. When natural light conditions are given in the laboratory, the females mostly lay diapausing eggs from the end of August onwards. In eggs without initial diapause, a larger number of embryos reach a stage, in which the embryonic diapause can be broken by chilling, only at favorable temperature (4 weeks at 24°C or 8 at 18°C) and in contact with water before the first winter. Thus, some individuals of a given population of M. roeseli have an annual, others a biennial life cycle. The variability in the duration of egg development is due to a photoperiodically induced, facultative initial diapause and to a possible quiescence caused by insufficient temperature and/or moisture.     

Immunofluorescence localization of α-amylase in the scutellum,germ aleurone and “normal” aleurone of germinated barley grains

Summary Using two step labeling with rhodamine-labeled secondary antibodies, -amylase (EC 3.2.1.1.) was detected in the scutellum, germ aleurone (monolayer partially encircling the scutellum) and normal aleurone (trilayer partially encircling the starchy endosperm; see Fulcher et al. 1972) in sections of Lowicryl-embedded barley (Hordeum vulgare L. cv. Himalaya) after imbibition of whole grains for 24, 48, and 72 h, but not after 2 h. Staining occurred over the protoplasts, cell walls or intercellular spaces of each tissue indicating that all three tissues had secreted as well as produced -amylase. The immunofluorescence in the scutellum was predominantly in the epithelium. Normal aleurone near the aleurone/ scutellum junction showed structural changes indicative of secretory activity by 24 h, and the pattern of cell erosion in the sub-aleurone and starchy endosperm at this and later stages supported this conclusion. The data show that normal aleurone is a major source of -amylase even at early stages of germination, but there is clear evidence also of production and secretion of some -amylase by both the scutellum and the germ aleurone, indicating that these tissues could also contribute to starch hydrolysis.Abbrevations GA₃ gibberellic acid - SDS sodium dodecyl sulphate - TBS 10 mM Tris, pH 7.4, containing 0.15 M NaCl - Tris 2-amino-2-(hydroxymethyl)-1, 3-propanediol     

Metabolism of a phenylcoumaran substructure lignin model compound in ligninolytic cultures of Phanerochaete chrysosporium

The degradation of the phenylcoumaran substructure model compound methyl dehydrodiconiferyl alcohol by the white-rot wood decay fungus Phanerochaete chrysosporium was investigated using culture conditions optimized for lignin oxidation. Initial attack was in the cinnamyl alcohol side chain, which was oxidized to a glycerol structure. This was subsequently converted by loss of the two terminal carbon atoms, C and C, to yield a C-aldehyde structure, which was further oxidized to the C-acid compound. The next detected intermediate, a phenylcoumarone, was produced by double bond formation between C and C, and oxidation of the C-alcohol to an aldehyde group. Further oxidation of C to an acid yielded the next intermediate. The final identified degradation product was veratric acid. No products from the 5-substituted aromatic ring, and no phenolic products, were found. The initial glycerol-containing intermediate was a mixture of the threo and erythro forms, and no optical activity could be found, suggesting that its formation might have involved nonstereospecific C-C epoxidation followed by non-enzymatic hydrolysis of the epoxide.Abbreviations TLC thin layer chromatography - LDA lithium diisopropyl amide - DDQ 2,3-dichloro-5,6-dicyanobenzoquinone - MS mass spectrometry - UV ultraviolet spectroscopy     

The relationships between the structure of paddy levees and the plant species diversity in cultural landscapes on the west side of Lake Biwa,Shiga, Japan

Paddy levees form networks of narrow linear habitats and play various roles in cultural landscapes. Traditional landscapes on the west side of Lake Biwa consist of paddy field terraces and both stone and soil levees that have been maintained by paddy field management using local resources. Paddy levees in this study site are principally classified into five different types. Our study points out how differences in paddy levee structure as well as in management practices influence the plant species. Seventeen paddy levee transects were split into four habitat types based on their species components by TWINSPAN. Spatial characteristics and physical structures of paddy levees depended on natural conditions and human activities. The species–area curves of each levee type showed a clear distinction: the soil, stone and abandoned curves were steep, while the concrete and consolidated ones were gentle. The vegetation on consolidated levees was utterly different from the vegetation on traditional levee types from the aspect of species richness and species components. Soil type levees contained various woody plant species and included more diverse and indigenous plant species than abandoned type levees.     

Induction of reproductive diapause in Bruchidius atrolineatus during the dry season in a Sahelian zone

Bruchidius atrolineatus (Pic) (Bruchidae: Coleoptera) is a bruchid beetle infesting Vigna unguiculata (Walp). During the dry season, adults are in reproductive diapause. Studies of adult populations in a traditional store containing contaminated pods of V. unguiculata show that the reproductive diapause is induced during the first larval instars. The temperature decrease from November to January probably is the main climatic factor inducing this diapause. The percentage of diapausing adults depends on the duration of the larval development at low temperatures. Experiments in climatic boxes confirm these results. At 12 h 25 °T-12 h 20° C 11–13 LD, a high proportion of the adults emerging from the V. unguiculata seeds are in reproductive diapause and the duration of their growth is variable. L1 L2 L3 larvae probably are sensitive stages to the thermal variations and the processes allowing emergence of diapausing adults probably are induced during these larval instars.

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Résumé Bruchidius atrolineatus (Pic) est un Coléoptère Bruchidae se développant en zone sahélienne aux dépens d'une légumineuse Vigna unguiculata. Pendant la saison sèche, les adultes sont en diapause reproductrice. Un suivi des populations d'adultes a été réalisé dans un grenier traditionnel en terre séchée contenant des gousses récoltées dans la nature et portant des ufs de B. atrolineatus. Il a permis de constater que la diapause reproductrice était induite durant les premières phases du développement larvaire. La décroissance des températures de Novembre à Janvier avec des minima de 15 ° C et des maxima de 25 °C est probablement le principal facteur permettant l'induction de cette diapause. L'introduction dans le grenier de gousses portant des ufs venant d'être émis à différentes périodes de la saison sèche montre que le pourcentage d'adultes diapausants dépend de la durée du développement larvaire aux températures basses. Des expériences réalisées dans des étuves programmées confirment ces résultats. A 12 h 25 °T/12 h 20 °C 11–13 LD, un taux élevé d'adultes émergeant des graines est en diapause reproductrice et la durée de leur développement post-embryonnaire est très variable. En conditions plus chaudes 12 h 40 °C/12 h 25 °C 11–13 LD, le taux d'adultes diapausants est plus réduit et la durée du développement plus courte. L'analyse de la croissance larvaire montre que les premiers stades larvaires sont probablement des stades sensibles aux variations thermiques. Les modifications physiologiques permettant l'émergence d'adultes diapausants ou sexuellement actifs seraient induites durant ces stades.

     

Diapause induction in the codling moth, Cydia pomonella: effect of larval diet

The effect of larval diet on diapause induction in the Israeli strain of the codling moth, Cydia pomonella (L.), was studied in a field trial using intact apple fruits of two varieties: Ana (early-ripening, in the end of June) and Granny Smith (late-ripening, in October). Diapause incidence increased as fruit age (determined as days from fruit-set) progressed. These results corroborate former studies on other strains of the codling moth, where excised fruits were used.The combination of 80-day-old, fully ripe, Ana fruit treatment with the longest days of the year, yielded 38% diapause. This result demonstrates that mature fruit (inducing diapause) cannot completely override the effect of long day (averting diapause), but does confirm that larval diet modifies the photoperiodic induction of diapause in the codling moth.Deceased, October 1988     

Genetic variation in the subunits of globulin-1 storage protein of French bean

Summary Charge and molecular weight heterogeneity of globulin-1 (G1) polypeptides of the bean, Phaseolus vulgaris L., were revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Different bean cultivars were classified into three groups: Tendergreen, Sanilac, and Contender on the basis of their protein subunit composition. Nine distinct major bands: 51,49, 48.5,48^T, 48^S, 47, 45.5, 45^S, and 45^C, and two minor bands: 46^T and 46^S were found to account for the three profiles seen on one-dimensional SDS-PAGE. Two-dimensional analysis revealed these eleven protein bands to be composed of a minimum of fourteen distinct protein subunits. The Tendergreen and Sanilac types differ in their G1 polypeptide composition. The protein patterns of the Contender types are intermediate, containing many protein subunits found in the patterns of the Tendergreen and Sanilac types suggesting a genetic and evolutionary relationship.     

Estimating the age of Antarctic larval fish from otolith microstructure using light and electron microscopy

Larval fish of Antarctica have very narrow rings on their otoliths (<1 m) that may not be resolved with light microscopy. In this study, age data from the otoliths of larval Nototheniidae (Gobionotothen gibberifrons and Lepidonotothen larseni), determined using light and scanning electron microscopy, are compared. Rings 0.4 m wide were observed on otoliths viewed under electron microscopy; however, light microscopy could only resolve rings 0.5 m wide. Scanning electron microscopy is more time consuming and costly than light microscopy but has greater resolving power and is recommended to validate ring counts made using light microscopy in otolith studies with Antarctic larval fish.     

A marked drop in the incidence of the null allele of the B gene of the fourth component of complement (C4B*Q0) in elderly subjects: C4B*Q0 as a probable negative selection factor for survival

Summary The incidence of allotypes of the genes of the fourth component (C4) and factor B of the complement system was compared in 252 persons under 45 years of fage (young group) with 482 people between 61 and 90 years of age (old group). One hundred people older than 90 years of age (nonagenarians) were also investigated. A striking difference was found between the young and old groups in the incidence (16.1% and 5.4%, respectively) of a silent gene of the C4B allele (C4BQ0). This difference was even more marked among young and old men (17.6% vs 3.4%). The incidence of the C4BQ0 allele in women dropped to the level of the men only in the nonagenarian group. The most probable explanation for this finding is that people carrying the C4BQO allele die from as yet unidentified disease(s) in their middle-age. Therefore, male (and to a lesser extent female) carriers of this allele may have a considerably shorter life expectancy than individuals without a silent gene in the C4B locus.     

Zur Pigmentarchitektonik der Großhirnrinde des Menschen

Zusammenfassung Mit Hilfe einer neu entwickelten Methode zur Darstellung der Neurolipofuscine werden die am Aufbau der Regio entorhinalis beteiligten Zellschichten elektiv hervorgehoben. Bei einem solchen Vorgehen werden die Unterschiede zwischen den einzelnen Zellarten stärker betont als im Nisslbild, weil nur eine Cytoplasmakomponente dargestellt wird. Diese Beschränkung erlaubt zugleich die Verwendung sehr dicker Schnitte (bis zu 800 ), die — aufgehellt — unter dem Stereomikroskop analysiert werden. Auf diese Weise lassen sich Verfugungen aneinandergrenzender Rindenregionen und Kantenbildungen einzelner Rindenschichten sicher erfassen.Die Schichten des Allocortex unterscheiden sich im Pigmentbild deutlich von denen des Isocortex. Sie gehen nicht kontinuierlich ineinander über. Die Rinde der Regio entorhinalis läßt sich in eine Lamina principalis externa (Pre) und eine Lamina principalis interna (Pri) gliedern. Die äußere und innere Hauptschicht sind meist durch einen zellarmen Faserstreifen (Lamina dissecans) voneinander getrennt. Beide Schichten lassen sich weiter unterteilen (Pre- Pre-, Pre-, Pri-, Pri-, Pri-).In der Regio entorhinalis des Menschen werden 16 Felder pigmentarchitektonisch voneinander unterschieden. Davon bestehen 11 Felder ausschließlich aus allocorticalen Schichten, während die restlichen Areae, welche den Übergang zum Isocortex bilden, aus einer wechselnden Zahl allo- und isocorticaler Zellschichten zusammengesetzt sind.Im Bereich des Gyrus parahippocampalis lassen sich 7 rein allocorticale Felder voneinander abgrenzen. Die Areae gruppieren sich ringartig mit stufenweise abnehmender Organisationshöhe um ein hoch differenziertes Zentrum, das im oralen und lateralen Bezirk der Regio entorhinalis liegt. Das kennzeichnende Merkmal für die zentralen Felder ist eine Aufspaltung von Pri- in drei Schichten (Pri-, Pri-, Pri-). In dem Feld e _{centr. lat.} sind alle drei Unterschichten der Lamina principalis externa enthalten, während in e _{centr. med.} Pre- fehlt. Die angrenzenden Felder mit einheitlichem Pri- lassen sich wieder in Arae mit Pre- (e _{interpol.lat.} , e _caud. ) und ein Gebiet ohne Pre- (e _{interpol. med.} ) gliedern. In den rostralen und medialen Abschnitten verschmelzen Pri- und Pri- zu einer einheitlichen Zellschicht und bilden damit das Feld e _oral. . An der Grenze zum Gyrus ambiens in Nähe des Sulcus rhinencephali inferior findet sich ein schmaler Rindenstreifen, in dem die Schichten der Lamina principalis externa nur mangelhaft ausgebildet sind. Diese limitrophe Zone setzt sich nach caudal in das Grenzfeld zum Praesubiculum (e _{marg. caud.} ) fort.Eine ähnliche areale Gradation wie im Gyrus parahippocampalis findet sich auch unter den vier Feldern des Gyrus ambiens. Das am höchsten organisierte Feld (ga _centr. ) liegt im caudalen und medialen Abschnitt und ist durch eine dreischichtige Lamina principalis interna und eine deutliche Lamina cellularis profunda ausgezeichnet. Im angrenzenden Feld ga _lat. ist Pri- stark reduziert. In ga _oral. findet sich nur eine einschichtige Lamina principalis interna. Der Grenzstreifen zum Mandelkernkomplex (e _{marg. oral.} ) besteht nur aus Teilen der äußeren Hauptschicht.Der breite Übergangsbereich von den rein allocorticalen Feldern der Regio entorhinalis bis zum Isocortex wird in vier Areae unterteilt, in denen allo- und isocorticale Schichten fugenartig ineinandergreifen. Die Stufungen ergeben sich dadurch, daß die einzelnen Zellamellen unterschiedlich weit vordringen. Eine modifizierte äußere Körnerschicht reicht bis in das Feld e _{trans. med.} ; zugleich wird Pre- in tiefer gelegene Rindenschichten verlagert. An der Grenze zu e _{trans. intermed.} endet Pre-. Die Spindelzellschicht beteiligt sich als ein weiteres isocorticales Element am Aufbau des intermediären Übergangsfeldes. Die seitlichen Kanten von Pre- und Pri- bilden die lineare Grenze zum lateralen Übergangsfeld, e _{trans. lat.} , dessen Struktur durch das Hinzutreten einer äußeren und inneren Pyramidenschicht bereits weitgehend dem Isocortex gleicht. Im Feld e _{trans. caud.} findet sich sowohl die Spindelzellschicht als auch Pre-. Es bildet damit eine Stufung zwischen dem medialen und intermediären Übergangsfeld, die jedoch nur im caudalen Abschnitt der Regio entorhinalis am Übergang zum Praesubiculum vorhanden ist.

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Pigmentarchitecture of the human cortex cerebriI. Regio entorhinalis

Summary By means of a newly developed method demonstrating neurolipofuscines the cellular layers constituting the regio entorhinalis are stained selectively. The differences between the individual cell types show up more clearly than in ordinary Nissl-preparations since by the new technique only one cytoplasmic component is stained. This limitation allows at the same time to use rather thick sections (up to 800 ), which — after clearing — are studied under the stereoscopic microscope. Thus indentations of neighbouring regions of the cortex and the edgelike formations of individual cortical layers can be demonstrated with certainty.The pigmentarchitecture of the allocortical layers differs clearly from that of the isocortex. The layers of the allocortex are not continuous with those of the isocortex. Within the regio entorhinalis the cortex can be divided into a lamina principalis externa (Pre) and a lamina principalis interna (Pri), which are separated by a narrow zone of fibers (lamina dissecans). The two main layers can be further subdivided (Pre-, Pre-, Pre-, Pri-, Pri-, Pri-).In the regio entorhinalis of man 16 areas can be distinguished by their pigmentarchitecture. 11 of these areas consist exclusively of allocortical layers, whereas the other areas which form the transitory part to the isocortex consist of various numbers of allo- and isocortical layers.In the region of the gyrus parahippocampalis 7 purely allocortical areas can be separated from each other. These areas are grouped in gradually decreasing levels of organisation round a highly differentiated center, which lies in oral and lateral parts of the regio entorhinalis. The characteristic feature of the central areas is a splitting of Pri- into three layers (Pri-, Pri-. Pri-). The area: e _{centr. lat.} contains all three sublayers of the lamina principalis externa, whereas in e _{centr. med.} Pre- is lacking. The neighbouring areas with uniform (not subdivided) Pri- can again be separated in areas with Pre- (e _{interpol. lat.} , e _caud. ) and a field without Pre- (e _{interpol. med.} ). In the rostral and medial parts Pri- and Pri- fuse forming an uniform cellular layer constituting the area: e _oral. . At the border of the gyrus ambiens near the sulcus rhinencephali inferior a narrow strip of cortex is to be found, in which the layers of the lamina principalis externa are only poorly developed. This limitrophic zone continues caudally into the border area to the praesubiculum (e _marg.caud. ).A similar areal gradation as in the gyrus parahippocampalis can be found in the four fields of the gyrus ambiens. The area with the highest organisation (ga _centr. ) is situated in the caudal and medial part of the gyrus ambiens and is characterised by a three layered lamina principalis interna and a clearly recognisable lamina cellularis profunda. In the neighbouring field ga _lat . Pri- is considerably reduced. In ga _oral. only an one layered lamina principalis interna is to be found. The border field to the amygdala (e _marg.oral. ) consists only of parts of the lamina principalis externa.The broad transitory region from the exclusively allocortical fields of the regio entorhinalis to the isocortex can be subdivided into four areas, in which allo- and isocortical layers meet in a zone of mutual indentations. The subdivision of the area is based on the different distances of penetration of the individual cellular layers. A modified lamina granularis externa extends into the field e _{trans. med.} ; at the same time Pre- is translocated into deeper cortical regions. At the border to e _{trans. intermed.} Pre- terminates. The lamina multiformis (VI) takes part as a further isocortical element in the construction of the area: e _{trans. intermed.} . The lateral edges of Pre- and Pri- form the linear border to the lateral transitory area (e _{trans. lat.} ), the structure of which resembles considerably that of the isocortex by additional appearance of a lamina pyramidalis externa and interna. In the area e _{trans. caud.} a lamina multiformis as well as the cellular layer Pre- is to be found, thus constituting a gradation between e _{trans. med.} and e _{trans. intermed.} , which, however, is present only in the caudal portions of the regio entorhinalis at the border to the praesubiculum.

Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Photoperiodism and thermoperiodism in the predatory mite Amblyseius potentillae are probably based on the same mechanism

Summary A comparative study was made of the photoperiodic and thermoperiodic induction of diapause in the phytoseiid mite Amblyseius potentillae. Sensitivity to thermoperiod was found to be highest during the protonymphal and deutonymphal stages, with some sensitivity still being present in the young adult. Summation of both photoperiodic and thermoperiodic cycles was shown to take place, which demonstrated the presence of a photoperiodic counter as well as a thermoperiodic counter in these mites. Vitamin A appeared to be necessary for some early step in the physiological mechanism of diapause induction and not just for the expression of the diapause response. The light sensitivity threshold for photoperiodic induction of diapause was found to be extremely low, viz. less than 0.02 W/cm². Moreover, the light sensitivity threshold appeared to be strongly temperature dependent in A. potentillae. Experiments in which the mites experienced various sequences of short-day photoperiods and short-day thermoperiods, applied either concurrently or in succession, showed that the information collected by the photoperiodic counter and the thermoperiodic counter is integrated into one induction sum. These results strongly suggest that photoperiodic and thermoperiodic induction of diapause in these mites is based on the same physiological mechanism.Abbreviations DD continuous darkness - LL continuous light - LD light-dark cycle (e.g. LD 16:8 is a cycle of 16 h of light and 8 h of darkness) - TC thermoperiodic cycle (e.g. TC 16:8 (27°: 15°) is a thermoperiod with a 16 h thermophase of 27 °C and an 18 h cryophase of 15°C)     

Effect of GABAmimetics on electrocorticographic spike discharges induced by guanidinoethanesulfonic acid (amidino-taurine) in the rat

The effect of guanidinoethanesulfonic acid (GES) on rat electrocorticograms (ECoG) and the effects of -aminobutyric acid (GABA) and GABA-agonists on the ECoG changes induced by GES were studied. Sporadic spike discharges began 2–5 min after 1 mol GES/10 l on filter paper was applied to the pia mater of the left sensorimotor cortex; spike discharges extended to the opposite cerebral hemisphere 60 min after the onset of the ipsilateral spike discharges. The spike discharges with a frequency of 5–10 spikes/min lasted until the end of the 4 hour recording. The induced spike discharges were suppressed when the original GES soaked filter paper was replaced by one containing GES (1 mol) supplement combined with taurine (1 mol/10 l). GABA (1 mol) and its receptor agonist, muscimol (10nmol) and (3R)-(–)-4-amino-3-hydroxybutyric acid (1 mol) also suppressed the GES-induced spike discharges when applied topically. Diazepam (DZP) (10 mg/kg) suppressed the GES-induced spike discharges 10 min after i.p. injection, but phenobarbital (20 mg/kg) increased the frequency and voltage of spike discharges 100 min following subcutaneous administration. Intraperitoneal injection of either valproate (200 mg/kg) or phenytoin (25 mg/kg), after the completion of the spike discharges, showed no effect. These findings suggest that neurotransmission or neuromodulatory effects of taurine participate in GES-induced seizure activity, and that GABA_A and DZP receptors may play a role in the mechanism that suppresses GES-induced seizures.     

Inhibition of Urease by Cyclic β-Triketones and Fluoride Ions

Competitive inhibition of soybean urease by 11 cyclic -triketones was studied in aqueous solutions at pH 7.4 and 36°C. This process was characterized quantitatively by the inhibition constant (K _i), which showed a strong dependence on the structure of the organic chelating agents (nickel atoms in urease) and varied from 58.4 to 847 M. Under similar conditions, the substrate analogue (hydroxyurea) acted as a weak urease inhibitor (K _i = 6.47 mM). At 20°C, competitive inhibition of urease with the ligand of nickel atoms (fluoride anion) was pH-dependent. At pH 3.85–6.45, the value of K _i for the process ranged from 36.5 to 4060 M. Three nontoxic cyclic -triketones with K _i values of 58.4, 71.4, and 88.0 M (36°C) were the most potent inhibitors of urease. Their efficacy was determined by the presence of three >C=O– groups in the molecule and minimum steric hindrances to binding with metal sites in soybean urease.     

An alpha-L-fucosidase from Thermus sp. with unusually broad specificity

An -L-fucosidase (E.C. 3.2.1.51) exhibiting a wide aglycon specificity expressed in ability of cleaving 1 6-, 1 3-, 1 4-, and 1 2-O-fucosyl bonds in fucosylated oligosaccharides, has been isolated from culture filtrate of Thermus sp. strain Y5. The -L-fucosidase hydrolyzes p-nitrophenyl -L-fucopyranoside with V _max of 12.0 ± 0.1 M/min/mg and K _m = 0.20 ± 0.05 mM and is able to cleave off about 90% of total L-fucose from pronase-treated fractions of fucosyl-containing glycoproteins and about 30% from the native glycoproteins. The purified enzyme is a tetramer with a molecular mass of 240 ± 10 kDa consisting of four identical subunits with a molecular mass of 61.0 ± 0.5 kDa. The N-terminal sequence showed homology to some -L-fucosidases from microbial and plant sources. Hydrolysis of p-nitrophenyl -L-fucopyranoside occurs with retention of the anomeric configuration. Transglycosylating activity of the -L-fucosidase was demonstrated in reactions with such acceptors as alcohols, N-acetylglucosamine and N-acetylgalactosamine while no transglycosylation products were observed in the reaction with p-nitrophenyl -L-fucopyranoside. The enzyme can be classified in glycosyl hydrolase family 29.     

Cohesive single-stranded ends of Streptomyces temperate bacteriophage R4.

Summary The cohesive single-stranded termini of temperate Streptomyces phage R4 were found to be complementary 11 base single-stranded 3-extended DNAs with the sequence: 5-CGCCGTGTCTT-3 3-GCGGCACAGAA-5     

Probing the conformation of hemoglobin presbyterian in the R-state

The influence of allosteric effectors on the R-state (liganded) conformation of Tg-HbP (human hemoglobin Presbyterian expressed in transgenic pig) has been probed using a number of biophysical techniques, and the results have been compared with that of liganded of HbA (human normal adult hemoglobin) to gain insight into the molecular basis of Asn-108()->Lys mutation–induced low-oxygen affinity of Hb. The nuclear magnetic resonance studies of Tg-HbP revealed that the conformation of the ₁₁ and ₁₂ interfaces of the protein in the deoxy state are indistinguishable from that of deoxy HbA, whereas the conformation of the microenvironment of His-103() of Tg-HbP, a residue of the ₁₁ interface, is distinct from that of HbA in the R-state. In addition, the Presbyterian mutation also influences the structure of oxy Hb in other regions of the molecule. First, it facilitates the generation of deoxy (T)-state marker at 14.2 ppm (from 2,2-dimethyl-s-silapentane-5-sulfonate) on the interaction of oxy Hb with inositol hexa-phosphate without changing the ligation state. Second, it increases the geminate yield of the 10 ns photoproduct of CO-Hb. Third, it enhances the propensity of phosphate to increase the geminate yield. Fourth, it potentiates the ability of phosphate to induce deoxy-like features at the heme environment in the R-state. Fifth, it induces T-state-like signatures at the switch and hinge regions of the ₁₂ interface. Finally, molecular modeling studies have indicated an increased affinity for the four anion binding sites mapped in the midcentral cavity of Hb caused by the presence of Lys-108(). In short, Lys-108() in HbP induces a propensity for oxy Hb to access T-like conformational features in different regions of the oxy Hb molecule and also enhances the T-like signatures in the oxy state on interaction with allosteric effectors without changing its ligation. Interestingly, the intrinsic T-like conformational features of the R-state of HbP, in addition to those induced by the addition of allosteric effectors to liganded HbP, appear to be reminiscent of features of the B-state conformation of Hb found in rHb 1.1 (recombinant hemoglobin). We propose that the lowered oxygen affinity of Tg-HbP in the presence of allosteric effectors is a consequence of an altered R-state conformation of Hb, which reflects the facilitation of switching the R-state of HbP to the T-state compared with the normal R-state of HbA, thereby reducing HbA's affinity to oxygen.     

Ganglioside-cholera toxin interactions: a binding and lipid monolayer study

Summary On t.l.c. plates ¹²⁵I-cholera toxin binds to a disialoganglioside tentatively identified as GD_lb with about 10 times less capacity than to ganglioside GM₁. Binding of labeled toxin to both gangliosides was abolished in presence of excess amounts of unlabeled B subunit. Ganglioside extracts from human or pig intestinal mucosa showed toxin binding to gangliosides GM₁ and GD_1b. In ganglioside-containing lipid monolayers the penetration of the toxin was independent of the ganglioside binding capacity.Abbreviations GM₂ Gal-NAc14Gal(3-2NeuAc)14G1c1Cer - GM₁ Gal3Ga1-NAc14Gal(32NeuAc)14G1c11Cer - GD_1a NeuAc23Ga113Gal-NAc14Gal(32NeuAc)14G1c11Cer - GD1b Gall3Gal-NAcl4Gal(32NeuAc82NeuAc)14Glc11Cer - GT_1b NeuAc23Ga113Ga1-NAcal4Gal(3-2NeuAc82NeuAc)14G1c11Cer - dpPC 1,2-hexadecanoyl-sn-glycero-3-phosphocholine - dpPE 1,2-hexadecanoyl-sn-glycero-3-phosphoethanolamine     

Influence of starvation on the larval development ofHyas araneus (Decapoda,Majidae)

The influence of starvation on larval development of the spider crabHyas araneus (L.) was studied in laboratory experiments. No larval stage suffering from continual lack of food had sufficient energy reserves to reach the next instar. Maximal survival times were observed at four different constant temperatures (2°, 6°, 12° and 18 °C). In general, starvation resistance decreased as temperatures increased: from 72 to 12days in the zoea-1, from 48 to 18 days in the zoea-2, and from 48 to 15 days in the megalopa stage. The length of maximal survival is of the same order of magnitude as the duration of each instar at a given temperature. Sublethal limits of early starvation periods were investigated at 12 °C: Zoea larvae must feed right from the beginning of their stage (at high food concentration) and for more than one fifth, approximately, of that stage to have at least some chance of surviving to the next instar, independent of further prey availability. The minimum time in which enough reserves are accumulated for successfully completing the instar without food is called point-of-reserve-saturation (PRS). If only this minimum period of essential initial feeding precedes starvation, development in both zoeal stages is delayed and mortality is greater, when compared to the fed control. Starvation periods beginning right after hatching of the first zoea cause a prolongation of this instar and, surprisingly, a slight shortening of the second stage. The delay in the zoea-1 increases proportionally to the length of the initial fasting period. If more than approximately 70 % of the maximum possible survival time has elapsed without food supply, the larvae become unable to recover and to moult to the second stage even when re-fed (point-of-no-return, PNR). The conclusion, based on own observations and on literature data, is that initial feeding is of paramount importance in the early development of planktotrophic decapod larvae. Taking into account hormonal and other developmental processes during the first moult cycle, a general hypothesis is proposed to explain the key role of first food uptake as well as the response pattern of the zoea-1 stage to differential starvation periods.Contribution to research project Experimentelle Marine Ökosystemanalyse sponsored by Bundesministerium für Forschung und Technologie, Bonn (Grant No. MFU-0328/1).     

Expression of storage-protein genes during soybean seed development

Mature seeds of Glycine max (L.) Merr. contain two major storage proteins, a glycosylated 7S protein (conglycinin) and a non-glycosylated 11S protein (glycinin). Accumulation of these proteins and their mRNAs during seed development in cv. Provar was studied by SDS polyacrylamide gel electrophoresis and by Northern (DNA-RNA) hybridization. The 11S acidic and basic subunits and the 7S and subunits began to accumulate 18–20 d after pollination, shortly after the termination of cell division in developing cotyledons, whereas the 7S and 11S A-4 subunits were not detected until one to two weeks later, during the maturation phase of development. Messenger RNAs for 7S and 11S proteins were first detected 14–18 d after pollination, several days before the accumulation of storage proteins. Extracts from embryonic axes contained reduced levels of the 7S subunit, very little 11S protein, no detectable 7S or 11S A-4 subunits, and an additional 7S subunit not found in cotyledons. Soybean axes and cotyledons therefore differ in their synthesis of seed storage proteins.Abbreviations cDNA complimentary DNA - mRNA messenger RNA - SDS sodium dodecyl sulfate     

Effect of hydration,photoperiod and temperature on diapause termination in eggs ofPetrobia (Tetranychina) harti (Acari: Tetranychidae)

Petrobia harti (Ewing) displays a facultative summer diapause in the egg stage. An adult female will lay only either diapause or non-diapause eggs throughout her life. In the laboratory, diapause eggs are laid by females which develop on detachedOxalis articulata leaves under long-day photoperiods and a relatively low temperature of 19±1°C.Diapause occurs in a stage of advanced embryonic development, in which the embryo appears U-shaped when observed from the egg's ventral side. Embryonic development ceased at this stage, and no further growth occurred when the eggs were kept under a relative humidity of about 70% in various photoperiod and temperature conditions. However, when the eggs were hydrated by placing them on wet cotton wool, development in some embryos (apparently in those which had completed their diapause development) proceeded beyond the U-stage at a rate similar to that in non-diapause embryos and the eggs hatched.Under LD 168 and 19±1°C or 26±1°C, the later from oviposition the period of egg hydration started, the higher the percentage of diapause termination. Under LD 168 and 26±1°C, diapause termination occurred mostly during the first week of hydration, while at 19±1°C mostly during the second and third week.At 26±1°C, in eggs hydrated 15 days but not 30 days from oviposition, the percentage of diapause termination was higher under a long-day than under a short-day photoperiod.Under LD 168, when the eggs were hydrated continuously from oviposition or starting 15, 30 and 45 days from it, the percentage of diapause termination was higher at 26±1°C than at 19±1°C.The percentage of diapause-laying adult females and the intensity of egg diapause were higher when the pre-imaginal mites grew at LD 1212 and 19±1°C, than when they grew at LD 168 and 26±1°C. This maternal effect on egg diapause intensity was expressed when the eggs were maintained at LD 1212 and 19±1°C but not at LD 168 and 26±1°C.