Edge preference of retinal and tectal neurons in common toads (Bufo bufo) in response to worm-like moving stripes: the question of behaviorally relevant ‘position indicators’

Summary Previous experiments have shown that during prey-catching behavior (orienting, snapping) in response to a worm-like moving stripe common toads.Bufo bufo (L.) exhibit a contrast-and direction-dependent edge preference. To a black (b) stripe moving against a white (w) background (b/w), they respond (R^*) preferably toward the leading (l) rather the trailing (t) edge (R _l ^* > R _t ^* ), thus displaying head preference. If the contrastdirection is reversed (w/b), the stripe's trailing edge is preferred (R _l ^* < R _t ^* ), hence showing tail preference. In the present study, neuronal activities of retinal classes R2 and R3 and tectal classes T5(2) and T7 have been extracellularly recorded in response to leading and trailing edges of a 3 ° × 30 ° stripe simulating a worm and traversing the centers of their excitatory receptive fields (ERF) horizontally at a constant angular velocity in variable movement direction (temporo-nasal or naso-temporal).The behavioral contrast-direction dependent edge preferences are best resembled by the responses (R) of prey-selective class T5(2) neurons (R_l R_t=101 for b/w, 0.31 for w/b) and T7 neurons (R_lR_t=61 for b/w, 0.41 for w/b); the T7 responses may be dendritic spikes. This property can be traced back to off-responses dominated retinal class R3 neurons (R_lR_t=61 for b/w, 0.51 for w/b), but not to class R2 (R_lR_t =1.21 for b/w and 0.91 for w/b). The respective edge preference phenomena are independent of the direction of movement.When stimuli were moved against a stationary black-white structured background, the head preference to the black stripe and the tail preference to the white stripe were maintained in class R3, T5(2), and T7 neurons. If the stripe traversed the ERF together with the structured background in the same direction at the same velocity, the responses of tectal class T5(2) and T7 neurons were strongly inhibited, particularly in the former. Responses of retinal R2 neurons in comparable situations could be reduced by about 50%, while class R3 neurons responded to both the stimulus and the moving background structure.The results support the concept that the prey feature analyzing system in toads applies principles of (i) parallel and (ii) hierarchial information processing. These are (i) divergence of retinal R3 neuronal output contributes to stimulus edge positioning and (in combination with R2 output) area evaluation intectal neurons and to stimulus area evaluation and (in combination with R4 output) sensitivity for moving background structures inpre tectal neurons; (ii) convergence of tectal excitatory and pretectal inhibitory inputs specify the property of prey-selective tectal T5(2) neurons which are known to project to bulbar/spinal motor systems.Abbreviations ERF excitatory receptive field - IRF inhibitory receptive field - N nasal - T temporal - R _w response to a worm-like stripe moving in the direction of its longer axis - R _A response to an antiworm-like stripe whose longer axis is oriented perpendicular to the direction of movement - R _l response to the leading edge of a worm-like moving stripe - R _t response to the trailing edge of a worm-like moving stripe - b/w black stimulus against a white background - w/b white stimulus against a black background - sm structured moving background - ss structured stationary background - u minimal structure width of a structured background consisting of rectangular black and white patches in random distribution - HRP horseradish peroxidase     

Genetics of fertility restoration in hybrid rice

Summary The cross combination involving 14 male-sterile lines in rice, when crossed with different maintainers, showed fertility restoration in certain combinations. When F₂ segregating populations were classified based on spikelet fertility, fertility restoration was shown to be governed by 31, 9331, and 1231, due to allelic differences. This indicated that the cytosterility of the same group showed monogenic fertility restoration, whereas crossing plants belonging to different cystosterile groups showed a digenic pattern of segregation.     

Evolutionary relationship between Enterobacteriaceae: comparison of the ATP synthases (F1F0) of Escherichia coli and Klebsiella pneumoniae

The ATP synthase complex of Klebsiella pneumoniae (KF₁F₀) has been purified and characterized. SDS-gel electrophoresis of the purified F₁F₀ complexes revealed an identical subunit pattern for E. coli (EF₁F₀) and K. pneumoniae. Antibodies raised against EF₁ complex and purified EF₀ subunits recognized the corresponding polypeptides of EF₁F₀ and KF₁F₀ in immunoblot analysis. Protease digestion of the individual subunits generated an identical cleavage pattern for subunits , , , , a, and c of both enzymes. Only for subunit different cleavage products were obtained. The isolated subunit c of both organisms showed only a slight deviation in the amino acid composition. These data suggest that extensive homologies exist in primary and secondary structure of both ATP synthase complexes reflecting a close phylogenetic relationship between the two enterobacteric tribes.Abbreviations ACMA 9-amino-6-chloro-2-methoxyacridine - DCCD N,N-dicyclohexylcarbodiimide - FITC fluorescein isothiocyanate - SDS sodium dodecyl sulfate - TTFB 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole     

The inheritance of host plant resistance and its effect on the relative infection efficiency of Magnaporthe grisea in rice cultivars

The inheritance of host plant resistance and its effect on the relative infection efficiency for leaf blast was studied in the crosses IR36/CO39 (partially resistant × highly susceptible) and IR36/IR64 (both partially resistant). On the natural scale, gene action appeared multiplicative. After log transformation, additive effects described most of the genetic variation in the cross IR36/CO39, while additive and dominance effects were about equal in magnitude in the cross IR36/IR64. Dominance was towards increased resistance. No transgressive segregation occurred in the cross IR36/CO39. The number of genes that reduce lesion number was estimated to be zero in CO39 and five or more in IR36. The cross IR36/IR64 showed transgressive segregation in both directions, and IR36 and IR64 each contain at least one gene that is not present in the other cultivar. The heritabilities (narrow sense) in the F₂ were low (range 0.06–0.16), while narrow sense heritabilities based on F₃ lines were much higher (range 0.41–0.68). Lesion numbers in F₃ lines were reasonably correlated with those in F₅ progenies derived from the same F₂ plant (r was±0.6 in both crosses). Partial resistance can be effectively improved by selecting the most resistant plants from the most resistant F₃ lines.     

Very slow growth of Bacillus polymyxa: Stringent response and maintenance energy

Bacillus polymyxa grown in a recycling fermentor shows the same behavior previously observed with Escherichia coli: 3 successive growth phases. In the last 2 phases the growth rate is linear and the apparent maintenance energy demand rate and the molar growth yield are both independent of the specific growth rate, , and of the cells mass. The final phase of very slow growth is an indefinitely prolonged state of strong, stringent control, the regulatory system based on guanosine 3-diphosphate 5-diphosphate, and guanosine 3-diphosphate 5-triphosphate. The maximum cost of this stringent response is calculated to be 9% of the energy available to these energy-limited cells. There is a further energy cost contained in substantial amounts of DNA, RNA, and protein released from the cells during the latter 2 growth phases. The cost of production of these extra cellular anabolites ranges from 8–11% of the available energy.After a carbon-energy upshift in phase 3, the population growth rate immediately returned to that of early phase 2 growth, 50 h or more earlier.If maintenance energy is considered as energy expended by cells to maintain homeostasis, catabolic capacity, or anabolic potential, then the cost of stringent control — which preserves the fidelity of protein synthesis in slowly growing cells — must be considered a maintenance energy cost.Abbreviations GPR glucose provision rate - F_R medium flow rate - S_R substrate concentration - V_F fermentor volume - F_S filtrate removal rate - ppGpp guanosine 3-diphosphate 5-diphosphate - pppGpp guanosine 3-diphosphate 5-triphosphate     

Inheritance of mitochondrial DNA in lentil (Lens culinaris Medik.)

Restriction fragment analysis was used to examine the inheritance of lentil mitochondrial DNA (mtDNA) in F₁ and F₅ progeny from intrasubspecific (Lens culinaris ssp. culinaris) crosses and in F₁ progeny from intersubspecific (Lens culinaris ssp. orientalis x L. culinaris ssp. culinaris) crosses. Southern blots of digested parental and progeny DNA were hybridized to heterologous maize mtDNA probes specific to coxI and atp6 genes. Two restriction fragment polymorphisms separated L.c. ssp. culinaris Laird and Eston from L.c. ssp. culinaris ILL5588, and one restriction fragment polymorphism distinguished L.c. ssp. culinaris Laird and Eston from L.c. ssp. orientalis LO4. Twelve of 13 f₁ progeny and all F₅ progeny from the intrasubspecific crosses, and all F₁ progeny from intersubspecific crosses had only maternal mtDNA restriction fragments. One f₁ plant from an Eston x ILL5588 cross inherited mtDNA fragments from both parents. Nuclear DNA inheritance was biparental in all F₁ progeny.NRCC No. 38451     

Spatial and temporal variation in soil CO2 efflux in an old-growth neotropical rain forest, La Selva, Costa Rica

Our objectives were to quantify and compare soil CO₂ efflux of two dominant soil types in an old-growth neotropical rain forest in the Atlantic zone of Costa Rica, and to evaluate the control of environmental factors on CO₂ release. We measured soil CO₂ efflux from eight permanent soil chambers on six Oxisol sites. Three sites were developed on old river terraces (old alluvium) and the other three were developed on old lava flows (residual). At the same time we measured soil CO₂ concentrations, soil water content and soil temperature at various depths in 6 soil shafts (3 m deep). Between old alluvium sites, the two-year average CO₂ flux rates ranged from 117.3 to 128.9 mg C m^–2 h^–1. Significantly higher soil CO₂ flux occurred on the residual sites (141.1 to 184.2 mg C m^–2 h^–1). Spatial differences in CO₂ efflux were related to fine root biomass, soil carbon and phosphorus concentration but also to soil water content. Spatial variability in CO₂ storage was high and the amount of CO₂ stored in the upper and lower soil profile was different between old alluvial and residual sites. The major factor identified for explaining temporal variations in soil CO₂ efflux was soil water content. During periods of high soil water content CO₂ emission decreased, probably due to lower diffusion and CO₂ production rates. During the 2-year study period inter-annual variation in soil CO₂ efflux was not detected.     

Quaternary structure of ATP synthases: Symmetry and asymmetry in the F1 moiety

It has been proposed that during ATP synthesis/hydrolysis F₁ ATPases experience a complex pattern of nucleotide binding and release during the catalytic cycle (binding change mechanism). This type of mechanism has implications that can be correlated with the structure of the enzyme. F₁-ATPases (stoichiometry ₃₃) are essentially a symmetrical trimer of pairs of the major subunits ( and ); the minor subunits (, and ) are in single copies and interact with the trimer in an asymmetrical fashion. The asymmetry introduced by the minor subunits has important structural and functional consequences: (1) it introduces differences between the potentially equivalent binding and catalytic sites in the major subunits, (2) it restricts the ways in which a binding change mechanism can occur, and (3) it governs the way in which the F₁ interacts with the (asymmetrical) F₀ sector.     

An assessment of the production and performance of F1 hybrid wheats based on Triticum timopheevi cytoplasm

Summary This work reports on the production and yield assessment of F₁ wheat hybrids from crosses between cytoplasmic male sterile lines, with Triticum timopheevi cytoplasm, and cultivars with fertility restoring genes.In four years of trials conducted between 1974 and 1977, only three F₁ hybrids out of a total of 168 yielded significantly more than the control variety Maris Huntsman, which currently occupies a substantial proportion of the area planted with winter wheat in the UK. Because of the rapid increase in yield of conventional wheat varieties, which has already led to varieties which outyielded Maris Huntsman, the yield advantage of these F₁ hybrids is insufficient for them to be developed as commercial varieties.The efficient production of uncontaminated male sterile and F₁ seed presents problems of isolation and a difficult biological problem in increasing the cross breeding potential of maintainer and restorer lines. These together with selection for other parental characters such as restoration, short straw and resistance to sprouting make the development of F₁ hybrids more difficult and expensive than that of conventional varieties.     

The expression of I-Ed molecules in F1 hybrid mice detected with antigen-specific,I-Ed-restricted cloned T-cell lines

The expression of polymorphic determinants on I-E molecules is largely dependent on allelic variation in the E chain. We have previously analyzed the expression of E ^k and E ^b chains in F₁ hybrid mice by a combination of techniques, and have shown that functional variation detected by the responsiveness of cloned T-cell lines specific for these molecules correlates well with serological determination of E expression. In the present study, we have extended our analysis to E ^d expression in F₁ hybrid mice. We show that E ^d is relatively poorly expressed in three F₁ combinations: H-2 ^d× H-2 ^b, H-2 ^d× H-2 ^s, and H-2 ^d× H-2 ^u. The former two crosses express E chains from the H-2 ^dparent only; when recombinant strains carrying E ^b or E ^s and an active E gene are used, E ^d expression is significantly increased. On the other hand, H-2 ^umice synthesize E chains; the poor expression of E ^d chains in this F₁ hybrid apparently reflects the strong preferential association of E ^u chains with all E molecules thus far analyzed. These results confirm that E chains compete for binding to E chains and that preferential association of different allelic forms of E chains with E chains is a generalized phenomenon. They also illustrate the importance of the rate of biosynthesis of Ia chains for cell-surface expression.     

Effect of phosphate and adenine nucleotides on the rate of labeling of functional groups at the catalytic site of F1-ATPase

The effect of inorganic phosphate, ADP, ATP, and their analogues on the rate of labeling of F₁-ATPase by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and phenylglyoxal have been investigated. Analysis of the kinetic data indicate that the labeled functional groups of the essential tyrosine and arginine residues respectively are both located at the catalytic site of F₁. The active phenolic group of tyrosine is located closer to the bound inorganic phosphate or the -phosphate group than the - and -phosphate groups of the bound ATP at the catalytic site, whereas the guanidinium group of arginine is located closer to the - and -phosphate groups of the bound ATP than to its -phosphate group or the bound inorganic phosphate. The kinetically deduced dissociation constants are 1.3 mM and 210 µM for the inorganic phosphate and ADP respectively bound to this catalytic site. Labeling the essential tyrosine residue by NDB-Cl has been found to facilitate subsequent labeling of the essential arginine residue by phenylglyoxal.Abbreviations NBD-Cl 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (this compound has been named 4-chloro-7-nitro-benzofurazan and abbreviated NBf-Cl elsewhere) - DTT dithiothreitol - EDTA ethylenediaminetetraacetic acid - P_i inorganic phosphate - PEP phosphoenolpyruvate - ADPCP ,-methylene-adenosine 5-triphosphate - AMPCP ,-methylene-adenosine 5-diphosphate - Hepes N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - Tris 2-amino-2(hydroxymethyl)-1,3-propanediol     

Identification of subunits required for the catalytic activity of the F1-ATPase

F₁() complexes containing equimolar ratios of the and subunits have been shown to function as active ATPases, whereas individually isolated and subunits show no real ATPase activity. These results indicate that the single-copy subunits are not required for F₁-ATPase activity. The minimal F₁()-core complexes exhibit, however, lower rates and some different properties from those of their parent whole F₁ or ₃₃ complexes. It is therefore concluded that for obtaining a full spectrum of the characteristic functional properties of an F₁-ATPase the presence of the F₁- subunit is also required. The implications of these findings on the subunit location of both catalytic and noncatalytic nucleotide binding sites is discussed.     

Endothelin-1 and insulin induce cellular inactivation of protein kinase FA/glycogen synthase kinase-3α in a common signaling pathway

In this study, we investigate the effects of endothelin-1 (ET-1) and insulin on the cellular activity of protein kinase F_A/glycogen synthase kinase-3 (kinase F_A/GSK-3) in rat adipocytes. The cellular activity of kinase F_A/GSK-3 is inhibited to 50% of control within 30 min when cells are treated with 1 nM ET-1 at 37°C; in addition, significant inhibition to 60% of control is observed at as low as 1 pM ET-1. Conversely, ET-1 at concentrations up to 1 nM has no direct effect on purified kinase F_A/GSK-3 in vitro. Immunoblotting analysis further reveals that the protein level of this kinase is not significantly changed when treated with 1 nM ET-1 for 30 min. Similar to ET-1, insulin as low as 10 nM can also induce inactivation of kinase F_A/GSK-3 to 50% of control in adipocytes when processed under identical conditions. Most importantly, when treated with both insulin and ET-1, the activity of kinase F_A/GSK-3 can be decreased only to 50% of control. Taken together, the results provide initial evidence that ET-1 and insulin may regulate this important multisubstrate/multifunctional protein kinase in a common signaling pathway in cells.     

Intracellular sites of the synthesis of sweet potato mitochondrial F1ATPase subunits

Summary Five subunits (-, -, -, - and -subunits) of the six -and -subunits) in the F₁ portion (F₁ATPase) of sweet potato (Ipomoea batatas) mitochondrial adenosine triphosphatase were isolated by an electrophoretic method. The - and -subunits were not distinguishable immunologically but showed completely different tryptic peptide maps, indicating that they were different molecular species. In vitro protein synthesis with isolated sweet potato root mitochondria produced only the -subunit when analyzed with anti-sweet potato F₁ATPase antibody reacting with all the subunits except the -subunit. Sweet potato root poly(A)⁺RNA directed the synthesis of six polypeptides which were immunoprecipitated by the antibody: two of them immunologically related to the -subunit and the others to the - and -subunits. We conclude that the -subunit of the F₁ATPase is synthesized only in the mitochondria and the -, - and -subunits are in the cytoplasm.     

Interaction of free fatty acids with the erythrocyte membrane as affected by hyperthermia and ionizing radiation

The interference of hyperthermia and ionizing radiation, respectively, with the effects of capric (100), lauric (120), myristic (140), oleic (cis-181) and elaidic (trans-181) acids on the osmotic resistance of human erythrocytes was investigated. The results are summarized as follows: (A) not only at 37°, but also at 42° and 47°C lauric acid (120) represents the minimum chain length for the biphasic behaviour of protecting against hypotonic hemolysis at a certain lower concentration range and hemolysis promotion at subsequent higher concentrations; (B) with increasing temperatures the protecting as well as the hemolytic effects occur at lower concentrations of the fatty acids; (C) the increase of temperature promotes the extent of hemolysis and reduces the extent of protection against hypotonic hemolysis; (D) Gamma-irradiation of erythrocytes selectively affects the concentration of oleic acid at which maximum protection against hypotonic hemolysis occurs, without altering the minimum concentration for 100% hemolysis.     

Inheritance of the fuzzless-lintless character in cotton (Gossypium hirsutum)

Summary A fuzzless-lintless mutant was identified in MCU.5 (Gossypium hirsutum) cotton in 1984. The inheritance of this character is reported in this paper. The fuzzless-lintless mutant was crossed with fuzzy-linted parents viz. MCU.5, MCU.7, Express Sindh (W), Piedmont Cleveland and Sindis Wild and the segregation pattern was studied in F₂ and BC₁F₁ generations. The segregation ratios for fuzzy-linted and fuzzless-lintless were 151 in the first cross, 631 in the second, third and fourth crosses and 2551 in the fifth cross. These ratios indicated that this character is controlled by 2–4 gene pairs, and the fuzzless-lintless character is a recessive to fuzzy-linted character. The chi-square test was significant only in the BC₁F₁ generation with MCU.7 and Express Sindh (W). The test revealed that the observed values deviated significantly from the expected ratio of 71, suggesting that this character is also influenced by modifier gene complex.     

F1 hybrid versus 32 selected F7 lines performance of common winter wheat (Triticum aestivum ssp. vulgare)

Summary One F₁ common wheat hybrid (Zlatna Dolina x Primépi) which had exhibited significant heterosis in a previous study was compared with 32 F₇ lines selected from the same cross. The yield test was planted in the 1976–1977 season at two locations: Zagreb, Yugoslavia (optimal environment) and Hutchinson, Kansas, USA (stress environment). The purpose of this experiment was to determine if a homozygous segregant superior to the F₁ hybrid could be obtained from the same cross combination.Heading date, plant height, disease incidence, grain yield and its components, protein content, and sedimentation value were examined at Zagreb. Germination, winterhardiness and grain yield were determined at Hutchinson.At Zagreb, the F₁ hybrid exhibited significant heterosis in grain yield, even though two of the three yield components were intermediate to parent values. Heterotic effects were greater in the stress environment (Hutchinson), mainly due to the poor winterhardiness and lower yield of one parent variety. At Zagreb, grain yield of the f₁ hybrid was significantly better than the best F₇ line. However at Hutchinson, the two leading F₇ Unes outyielded the f₁ hybrid, but differences were not significant.It can be concluded that genes involved in heterosis in the hybrid, Zlatna Dolina x Primépi, were not fixed in the homozygous lines selected from the same cross.     

Hypothyroidism Leads to a Decreased Expression of Mitochondrial F0F1-ATP Synthase in Rat Liver

In liver mitochondria isolated from hypothyroid rats, the rate of ATP synthesis is lower than in mitochondria from normal rats. Oligomycin-sensitive ATP hydrolase activity and passive proton permeability were significantly lower in submitochondrial particles from hypothyroid rats compared to those isolated from normal rats. In mitochondria from hypothyroid rats, the changes in catalytic activities of F₀F₁-ATP synthase are accompanied by a decrease in the amount of immunodetected -F₁, F₀1-PVP, and OSCP subunits of the complex. Northern blot hybridization shows a decrease in the relative cytosolic content of mRNA for -F₁ subunit in liver of hypothyroid rats. Administration of 3,5,3-triodo-L-thyronine to the hypothyroid rats tends to remedy the functional and structural defects of F₀F₁-ATP synthase observed in the hypothyroid rats. The results obtained indicate that hypothyroidism leads to a decreased expression of F₀F₁-ATP synthase complex in liver mitochondria and this contributes to the decrease of the efficiency of oxidative phosphorylation.     

Occurrence of pppApp-synthesizing activity in actinomycetes and isolation of purine nucleotide pyrophosphotransferase

The occurrence of adenosine 5-triphosphate-3-diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, Actinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and imperfecti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeniety from the culture filtrate. The enzymes are a monomeric protein with a molecular weight of 18000–26000 and synthesize adenosine, guanosine and inosine 5-phosphate (mono, di or tri)-3-diphosphate such as pApp, ppApp, pppApp, pGpp, ppGpp, pppGpp and pppIpp by transferring a pyrophosphoryl group from the 5-position of ATP, dATP and pppApp to the 3-position of purine nucleotides in the presence of a divalent cation and in alkaline state.Abbreviations pppApp adenosine 5-triphosphate 3-diphosphate - ppApp adenosine 5-diphosphate 3-diphosphate - pApp adenosine 5-monophosphate 3-diphosphate - pppGpp guanosine 5-triphosphate 3-diphosphate     

The αβ complexes of ATP synthase: the α3β3 oligomer and α1β1 protomer

The basic structures of the catalytic portion (F₁, ₃₃) of ATP synthase are the ₃₃ hexamer (oligomer with cooperativity) and ₁₁ heterodimer (protomer). These were reconstituted from the and subunits of thermophilic F₁ (TF₁), and the ₃₃ hexamer was crystallized. On electrophoresis, both the dimer and hexamer showed bands with ATPase activity. Using the dimer and hexamer, we studied the nucleotide-dependent rapid molecular dynamics. The formation of the hexamer required neither nucleotide nor Mg. The hexamer was dissociated into the dimer in the presence of MgADP, while the dimer was associated into the hexamer in the presence of MgATP. The hexamer, like mitochondrial F₁ and TF₁, showed two kinds of ATPase activity: one was cooperative and was inhibited by only one BzADP per hexamer, and the other was inhibited by three BzADP per hexamer.