Epizooic ciliates (Vorticella sp.) compete for food with their host Daphnia longispina in a small polyhumic lake

Summary Clearance rates of epizooic ciliates (Vorticella sp.) were measured together with their host, a planktonic cladoceran Daphnia longispina by using fluorescent latex beads as tracers of food. Vorticellans and their host graze on food of same size range (nanoplanktonic algae and bacteria). Individual clearance rates of Vorticella averaged 6.9 and 7.0 l ind^-1 h^-1 and those of Daphnia 463 and 708 l ind^-1 h^-1 for beads with diameter 2.00 and 3.92 m. On the average, epizooic vorticellans together on the carapace of Daphnia cleared particles with rates representing 25–33% of that the host cleared, the maximum rates being 50–80%. In a steeply stratified polyhumic lake vorticellans take advantage of following Daphnia to food patches and they can severely compete for food with their host.     

Ecology of Proteus flagellar phages

Summary Phages identical to X ₇ in host range and serological properties are liberated by several Proteus strains. Another Proteus flagellar phage, X ₈, differs from X ₇ antigenically and in host range.     

Spectroscopic studies of bound cytochrome c and an iron-sulfur center in a purified reaction center complex from the green sulfur bacterium Chlorobium tepidum

Flash-induced optical kinetics at room temperature of cytochrome (Cyt) c ₅₅₁ and an Fe-S center (CF_A/CF_B) bound to a purified reaction center (RC) complex from the green sulfur photosynthetic bacterium Chlorobium tepidum were studied. At 551 nm, the flash-induced absorbance change decayed with a t _1/2 of several hundred ms, and the decay was accelerated by 1-methoxy-5-methylphenazinium methyl sulfate (mPMS). In the blue region, the absorbance change was composed of mPMS-dependent (Cyt) and mPMS-independent component (CF_A/CF_B) which decayed with a t _1/2 of 400–650 ms. Decay of the latter was effectively accelerated by benzyl viologen (Em –360 mV) and methyl viologen (–440 mV), and less effectively by triquat (–540 mV). The difference spectrum of Cyt c had negative peaks at 551, 520 and 420 nm, with a positive rise at 440 to 500 nm. The difference spectrum of CF_A/CF_B resembled P430 of PSI, and had a broad negative peak at 430435 nm.Abbreviations (B)Chl (bacterio)chlorophyll - Cyt cytochrome - F_A, F_B and F_X iron-sulfur center A, B and X of Photosystem I - CF_A, CF_B and CF_X F_A-,F_B- and F_X-like Fe-S center of Chlorobium - mPMS 1-methoxy-5-methylphenazinium methyl sulfate - PSI Photosystem I - RC reaction center     

Association of gangliosides to fibroblasts in culture: A study performed with GM1 [14C]-labelled at the sialic acid acetyl group

The preparation of a G_M1-ganglioside (GM1) [¹⁴C]-labelled in the sialic acid residue is reported. This can be obtained by re-N-acetylation in the presence of [1-¹⁴C]-acetic anhydride, of a GM1 derivative de-N-acetylated specifically on the sialic acid residue by alkaline hydrolysis of GM1 with tetramethylammonium hydroxide. The radiolabelled GM1 is utilized to investigate the binding properties and the mode of interaction of GM1 with cultured fibroblasts. Three different forms of association (one serum-removable, one trypsin-removable and one trypsin-stable) have been recognized to occur in a way that depended on cell culture conditions (presence or absence of fetal calf serum), ganglioside concentration (from, 5×10^–9 M to 10^–4 M) and incubation time (up to 24 h). Some metabolic modifications of GM1 during the period of high cell viability were also investigated.Abbreviations GM1 G_M1-ganglioside, II³NeuAc-GgOse₄Cer - FCS fetal calf serum - EMEM Eaglés Minimum Essential Medium with Earlés salts - PBS Dulbecco phosphate buffered saline without calcium and magnesium     

Psychological changes associated with self-regulatory treatments of irritable bowel syndrome

The psychological side effects of self-regulatory treatment (a combination of relaxation, thermal biofeedback, and cognitive therapy) for irritable bowel syndrome (IBS) were compared among 20 successfully treated patients, 12 unsuccessfully treated patients, and 9 patients who merely monitored symptoms for 12 weeks. Pretreatment and posttreatment scores on the Beck Depression Inventory, State-Trait Anxiety Inventory, and Psychosomatic Symptom Checklist were examined. Successfully treated patients had significant (p<.01) reductions on all measures and significantly greater reductions on depression and state anxiety than the symptom monitoring group. Interestingly, the failures also showed a significant (p=.027) reduction in trait anxiety and no significant increases on other measures.     

Genetic and environmental considerations for evaluating crown position of wheat

Summary Crown position affects winter survival of fallsown wheat (Triticum aestivum L.) Direct or indirect selection for crown depth has been little practiced. Reports have suggested that short subcrown internode length was closely related to semidwarf plant height and that semidwarfism was related to poor emergence. This study determined the relationships among crown depth, plant height, and emergence rate index in three wheat populations. The efficiency of evaluating crown placement in the field was examined and additional information was obtained on its genetic control. The F₂-derived F₄ and F₅ lines from the crosses of female parents Daws, Nugaines, and Stephens with male parent Selection 7952 were planted at Central Ferry and Pullman, Washington, respectively. Correlations from each population indicated that crown depth and subcrown internode length were not closely associated with plant height and emergence rate index. Crown depth was a more reliable indicator of crown placement than subcrown internode length. Adjustment of the data for seed depth differences was essential for evaluating subcrown internode length but less important for evaluating crown depth. After adjustment for seed depth, narrow-sense h ² values for subcrown internode length and crown depth were 0.25–0.41. Crown depth and subcrown internode length were inherited as quantitative traits in phenotypes that expressed variable dominance. Modest gains due to selection for crown depth were achieved.Contribution from USDA-ARS and College of Agriculture and Home Economics Research Center, Washington State University, Scientific Paper No. 7795     

Nitrous oxide production by nitrogen-fixing,fast-growing Rhizobia

Rhizobium trifolii, R. leguminosarum, andR. hedysarum, grownex planta under anoxic conditions in a chemically defined medium, evolve N₂O from NO₃ ^–, NO₂ ^–, and (NH₄)₂NO₃. The amount of nitrous oxide formed after 96 hours is about 0.2M×mg^–1 cells d.w. Large availability of organic matter enhances the production of N₂O from nitrate by free-livingR. trifolii in peat/sand mixtures. Denitrification of the above species andR. meliloti was detected also in planta. Nitrous oxide production increases almost linearly from 10–45M×mg^–1 nodules d.w. when nitrogen-fixing plants are exposed to increasing concentrations of nitrate (1–12M).     

Ganglioside lactones:1H-NMR determination of the inner ester position of GD1b-ganglioside lactone naturally occurring in human brain or produced by chemical synthesis

The complete definition of the chemical structure of G_D1b-ganglioside (G_D1b) lactone isolated from human brain has been given by means of spectrometric and spectroscopic analyses. G_D1h lactone contains a single ester linkage involving the external sialic acid carboxyl group and the C-9 hydroxyl group of the internal sialic acid unit. A synthetic lactone of G_D1b prepared treating G_D1b with glacial acetic acid characterized in the same way showed an identical chemical structure.Abbreviations: Ganglioside nomenclature is according to Svennerholm [16] and the IUPAC-IUB Recommendations [17] G_M1 G_M1-ganglioside, II³NeuAc-GgOse₄Cer, Gal1-3GalNac1-4[NeuAc2-3]Gal1-4Glc1-1Cer - G_D1b G_D1b-ganglioside, II³(NeuAc)₂GgOse₄Cer, Gal1-3GalNAc1-4[NeuAc2-8NeuAc2-3]Gal1-4Glc1-1Cer - G_D1b lactone G_D1b-L, Gal1-3GalNAc1-4[NeuAc(1-9)2-8NeuAc2-3]Gal1-4Glc1-1Cer - Cer ceramide - FAB-MS fast atom bombardment-mass spectrometry - ¹H-NMR proteon nuclear magnetic resonance - 1D-NMR one dimensional NMR - 2D-COSY two dimensional correlated spectroscopy - DMSO-d₆ deuterated dimethylsulfoxide     

Sister chromatid exchange analysis of the 15q11 region in Prader-Willi syndrome patients

Summary Prader-Willi syndrome (PWS) is a sporadic disorder in which about half of cases have a 15q12 deletion. Although a small number of cases have other rearrangements involving 15q12, the rest of the cases appear to have normal chromosomes. Clinical similarities among all these patients regardless of the karyotype strongly suggests a common etiology. To investigate the nature of this common etiology, we analyzed sister chromatid exchange (SCE) at the 15q11-13 region in 10 PWS patients with the chromosome deletion, 12 PWS patients with normal chromosomes, and 11 normal control individuals. While SCE at the q11-13 region was absent on the 15q12 deleted chromosome, the percentage of SCE on chromosome 15 at q11 was statistically higher for PWS with normal chromosomes (10.1%) compared to that for normal controls (1.9%) and the normal homologue (2.2%) in deleted patients (²=7.7982, df=2, P<0.025). The data suggest relative instability of DNA at the 15q11 region in PWS patients.     

Asymmetric diffusion into the postsynaptic neuron: An extremely efficient mechanism for removing excess GABA from synaptic clefts on the Deiters' neurone plasma membrane

Microdissected Deiters' neuron plasma membranes have been used for studying the passage of GABA through the membrane both in the inward and outward direction. Working with 0.2 mM GABA in the compartment simulating the outside of the neurone and with 2.0 mM GABA in the one simulating the inside we found a net transport of GABA towards the inside. This mechanism does not require a Na⁺ ion gradient across the membrane. The nature of the transport process involved was studied by determining the rate of [³H]-GABA inward passage as a function of GABA concentration (1 nM–800 M) on the outward side of the membrane. The results have shown that until 50 M a diffusion process (v=D₁×C, where D₁=3.1×10^–11 1/m²×sec) is the sole mechanism involved. Above 50 M a second diffusion process is activated v=D₂×(C–50×10^–6), where D₂=2.8×10^–11 1/m²×sec. Taking in account both inward and outward directed diffusion, one can calculate 16 M as the equilibrium concentration of GABA on the outward side of the membrane. From a kinetic point of view, these diffusion processes are able to reduce GABA concentration in a synaptic cleft from 3 mM to 20 M within 3 sec. These diffusion systems are discussed as extremely efficient in removing the excess of released GABA in the synaptic cleft.     

Phytoavailability of Cd and Zn in soil estimated by stable isotope exchange and chemical extraction

The distribution of labile Cd and Zn in two contrasting soils was investigated using isotopic exchange techniques and chemical extraction procedures. A sewage sludge amended soil from Great Billings (Northampton, UK) and an unamended soil of the Countesswells Association obtained locally (Aberdeen, UK) were used. ¹¹⁴Cd and ⁶⁷Zn isotopes were added to a water suspension of each soil and the labile metal pool (E-value) determined from the isotope dilution. Samples were obtained at 13 time points from 1h to 50 days. For the sewage sludge amended soil, 29 g Cd g^–1 (86% of total) and 806 g Zn g^–1 (65% of total) were labile and for the Countesswells soil the value was 8.6 g Zn g^–1 (13% of total); limits of detection prevented a Cd E-value from being measured in this soil. The size of the labile metal pool was also measured by growing plants for 90 days and determining the isotopic content of the plant tissue (L-value). Thlaspi caerulescensJ. & C. Presl (alpine penny cress), a hyperaccumulator of Zn and Cd, Taraxacum officinale Weber (dandelion) and Hordeum vulgare L. (spring barley) were used. L-values were similar across species and lower than the E-values. On average the L-values were 23±0.8 g Cd g^–1 and 725±14 g Zn g^–1 for the Great Billings soil and 0.29±0.16 g Cd g^–1 and 7.3±0.3 g Zn g^–1 for the Countesswells soil. The extractable metal content of the soils was also quantified by extraction using 0.1 M NaNO₃, 0.01 M CaCl₂, 0.5 M NaOH, 0.43 M CH₃COOH and 0.05 M EDTA at pH 7.0. Between 1.3 and 68% of the total Cd and between 1 and 50% of the total Zn in the Great Billings soil was extracted by these chemicals. For the Countesswells soil, between 6 and 83% of the total Cd and between 0.1 and 7% of the total Zn was extracted. 0.05 M EDTA and 0.43 M CH₃COOH yielded the greatest concentrations for both soils but these were less than the isotopic estimates. On the whole, E-values were numerically closer to the L-values than the chemical extraction values. The use of isotopic exchange provides an alternative estimate of the labile metal pool within soils compared to existing chemical extraction procedures. No evidence was obtained that T. caerulescens is able to access metal within the soil not freely available to the other plants species. This has implications for long term remediation strategies using hyperaccumulating plant species, which are unlikely to have any impact on non-labile Cd and Zn in contaminated soil.     

The role of light in formation of modified S2-state upon low pH-treatment of oxygen-evolving Photosystem II

An abnormal, structurally modified, kinetically stable S₂-state has been reported to be induced when Photosystem II was treated with NaCl-EGTA (or EDTA) in the light or with pH in darkness, both are assumed to release functional Ca²⁺. In order to compare the mechanism of induction of modified S₂-state between the two treatments, effects of illumination during or before low pH-treatment on formation of the abnormal S₂-state were investigated by means of thermoluminescence measurements and low temperature EPR spectroscopy. Following results have been obtained: Flash illumination during low pH-treatment did not practically induce the abnormal S₂-state, whereas preflash illumination given immediately before low pH-treatment efficiently induced the abnormal S₂-state, and its amplitude showed a period-four oscillation on varying the preflash number with maxima at the second and sixth flashes. The abnormal S₂-state thus induced by preflashes was identical with the modified S₂-state that could be induced in dark-low pH-treated Photosystem II by excitation at 0°C after neutralization to pH 6.5. It was inferred that in low pH-treatment, modified S₂-state can be formed from both S₂- and S₃-states, but its yield from the latter is much higher than from the former, consistent with the early results by Boussac et al. obtained for NaCl-EGTA-light or NaCl-citrate-light treatment.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - EDTA ethylenediaminetetraactate - EGTA ethylene glycol bis(-aminoethylether)-N,N,N,N-tetraacetic acid - Mes 2-(N-morpholino)ethanesulfonic acid - PS II Photosystem II     

Molecular cloning of the T4 genome: organization and expression of the tail fiber gene cluster 34--38

Summary T4 derivatives that carry T4 tail fiber genes 34–38 have been isolated and characterized by genetic, structural and functional analysis. 32 T4 recombinants were identified by a marker rescue screen of 310 T4 clones generated by restriction of partial cytosine-containing T4 DNA with either HindIII or EcoRI and ligation into appropriately cleaved vectors. These tests defined 15 recombinant classes with respect to the contiguous stretches of genome recovered. Restriction enzyme structural analysis identified 7 HindIII fragments and 7 EcoRI fragments, established a restriction map covering about 11 kb, and indicated the orientation of the DNA inserts within the vectors. The cloned tail fiber genes are expressed efficiently from promoters and complement in vivo T4 phage carrying amber mutations in the tail fiber genes. Polypeptides corresponding to gp34-gp38 have been detected by SDS polyacrylamide gel electrophoresis of ³⁵S-labeled extracts of appropriate T4 recombinant infected UV-treated host cells. The genetic, structural and functional maps of the T4 tail fiber gene cluster have been correlated, and provide a rational approach to genetically directed DNA sequence analysis of genes 34–38 and their mutant variants that affect the assembly, structure and function of the tail fibers.     

Associations between isozyme phenotypes and environment in the slender wild oat (Avena barbata) in Israel

Summary Collections from 31 populations of A. barbata from diverse habitats in Israel were assayed electrophoretically for seven enzyme systems. Phenotype frequencies were scored in nine enzyme zones, probably representing 27 loci, to determine isozyme variability within and among populations. Many different isozyme phenotypes were found in all of the populations; also the array of isozyme phenotypes found in each population differed distinctly from that found in each other population. Overlays of phenotypic frequencies on map locations showed that isozyme variability is distributed in mosaic patterns not related to geographical distance. Principal-component and multiple-regression analyses revealed that temperature and moisture-related variables are significantly correlated with particular isozyme phenotypes. Further, the mosaic patterns of isozyme variation were found to correspond closely to mosaic patterns of the habitat. This structuring of the genetic variability into multilocus combinations was attributed to the combined effects of directional and diversifying selection. Comparisons of patterns and extent of genetic variation in Israel and California led to the conclusion that the evolution of ecotypes, each adapted to a specific habitat and marked by a particular set of enzyme alleles, has proceeded further in Israel, where A. barbata is endemic, than in California, where it is a recent introduction.This study was supported in part by NSF Grant BMS-01113-A01. Seed collections were supported by a United States-Israel Binational Science Foundation Grant     

An inducible change in state on the chromosomes of Sciara: Its effects on the genetic components of the X

Normally in Sciara males the sex chromosome constitution of the soma (X ^m O) differs from that of the germ line (X ^m X ^p ), the single X being of maternal origin. Males which are patroclinous for their sex-linked genes (X ^p O) are found regularly among the progeny of females heterozygous for any one of a number of X-translocations (X X ^t ). The patroclinous males are almost invariably completely sterile. In the present study a comparison is made of the patroclinous males derived from 5 different X-translocations in S. coprophila. The study includes data on the morphology and sexual behavior of the males as well as the cytology of the testis from late 4th instar through pupal life. The study is oriented towards the basic question of whether the paternally-derived X — normally destined to be eliminated — can function properly when it is retained. The comparative study supports our original suggestion that the patroclinous males arise from no-X eggs following 31 disjunction during oogenesis.Dedicated to Professor J. Seiler on the occasion of his 80th birthday.The studies reported here were supported by the National Science Foundation, grants GB-42 and GB 2857, and in part by Contract No. AT-(40-1)-2690 under the Division of Biology and Medicine, U. S. Atomic Energy Commission.     

Germinal reversion of an unstable mutation for anthocyanin pigmentation in soybean

Summary Plants of the w4-mutable line of soybean [Glycine max (L.) Merr.] are chimeral for anthocyanin pigmentation. Mutable plants produce both near-white and purple flowers, as well as flowers of mutable phenotype with purple sectors on near-white petals. It is established here that the mutable trait is conditioned by an unstable recessive allele of the w4 locus that conditions anthocyanin biosynthesis. The gene symbol w4-m is assigned to the mutable allele. Allele w4-m was derived from a stable, wild-type W4 progenitor allele and reverts at high frequency to a stable, wild-type W4 allele. Reversion occurs both early and late during the development of the germ line. Several experiments give estimates of germinal reversion frequency, indicating that approximately 6% of mutable alleles revert to wild-type from one generation to the next. Allele w4-m exhibits many features typical of an allele controlled by a transposable element.     

Modulation of formation of tumor metastases by peritoneal macrophages elicited by various agents

Summary We have studied the formation of experimental B16 melanoma metastases in the lungs of mice inoculated IV with tumoricidal or nontumoricidal peritoneal macrophages elicited by various agents. IV inoculation of peritoneal M elicited by Brewer's thioglycollate medium (TG-M) 1 day before the injection of B16 melanoma cells dramatically increased the number of metastatic foci in the lungs. NIH thioglycollate broth and proteose peptone each elicited a relatively low number of M, which were morphologically distinguishable from TG-M and did not influence the yield of B16 melanoma colonies in the lungs. Resident or C. pravum-elicited M also did not augment metastatis formation. TG-M became highly tumoricidal after IP stimulation with poly I: C. However, tumoricidal TG-M inoculated IV 1 day before IV inoculation of B16 melanoma cells did not have an antimetastatic effect. On the contrary, both tumoricidal and nontumoricidal TG-M augmented metastasis formation. Poly I: C treatment had a substantial antimetastatic effect in the normal mice, but not in mice with adoptively transferred TG-M. Histological analysis revealed that IV-inoculated TG-M (tumoricidal or nontumoricidal, either viable or disrupted) induced severe intravascular reaction in the lungs, but not in the liver or kidney. This reaction manifested in the aggregation of the various blood cells, preferentially neutrophils. These reactions were not observed after IV inoculation of PM or NIH TG-M.Intravascular inflammatory reactions induced by TG-M may be responsible for the augmentation of metastasis formation, partly by suppression of NK reactivity and mostly by the acceleration of the processes of tumor cell extravasation. These data may provide some insight into the failure to achieve systemic adoptive immunotherapy using activated peritoneal TG-M. Abbreviations used in this paper are: TG-M, thioglycollate-elicited macrophages; PM, proteose-peptone-elicited macrophages; NIH TG-M, macrophages elicited with NIH thioglycollate broth; CP-M, macrophages; elicited with C. parvum; poly I: C, polyinosinic: polycytidylic acid; TGM, thioglycollate medium; NIHTGB, NIH thioglycollate broth     

Cytoskeletal-associated protein kinase and phosphatase activities from cerebral cortex of young rats

We describe the phosphorylation system associated with the Triton-insoluble cytoskeletal fraction that phosphorylates in vitro the 150 kDa neurofilament subunit (NF-M) and alpha and beta tubulin from cerebral cortex of rats. The protein kinase activities were determined in the presence of 20 M cyclic AMP (cAMP), 1 mM calcium and 1 M calmodulin (Ca²⁺/calmodulin) or 1 mM calcium, 0.2 mM phosphatidylserine and 0.5 M phorbol 12,13-dibutyrate (Ca²⁺/PS/PDBu). Phosphorylation of these cytoskeletal proteins increased approximately 35% and 65% in the presence of cAMP and Ca²⁺/calmodulin, respectively, but was unaffected in the presence of Ca²⁺/PS/PDBu. Basal phosphorylation of these proteins studied increased approximately 35% and 72% in the presence of 0.5 M okadaic acid and 0.01 M microcystin-LR, respectively, suggesting the presence of phosphatase type 1. Results suggest that at least two protein kinases and one protein phosphatase are associated with the Triton-insoluble cytoskeletal fraction from cerebral cortex of rats.     

Purification and characterization of a thermostable β-galactosidase with high transgalactosylation activity from Saccharopolyspora rectivirgula

We purified an extracellular thermostable -galactosidase of Saccharopolyspora rectivirgula strain V2-2, a thermophilic actinomycete, to homogeneity and characterized it to be a monomeric enzyme with a relative molecular mass of 145 000 and s°_20,w of 7.1 s. In addition to the hydrolytic activity of 1-O-substituted -d-galactopyranosides such as lactose [a Michaelis constant K _m=0.75 mm and molecular activity (k _cat)= 63.1 s^–1 at pH 7.2 and 55° C] and p-nitrophenyl -d-galactopyranoside (K _m=0.04 mm k _cat= 55.8 s^–1), the enzyme had a high transgalactosylation activity. The enzyme reacted with 1.75 m lactose at 70°C and pH 7.0 for 22 h to yield oligosaccharides in a maximum yield (other than lactose) of 41% (w/w). A general structure for the major transgalactosylic products could be expressed as (Gal)_c-Glc, where n is 1, 2, 3, and 4 with a glucose at a reducing terminal. These oligosaccharides could selectively promote the growth of the genus Bifidobacterium found in human intestines. S. rectivirgula -galactosidase was stable at pH 7.2 up to 60°C (for 4 h in the presence of 10 m MnCl₂) or 70°C (for 22 h in the presence of 1.75 m lactose and 10 m MnCl₂). Thus the enzyme is applicable to an immobilized enzyme system at high temperatures (60°C <) for efficient production of the oligosaccharides from lactose. Correspondence to: T. Nakayama     

Regression and model-building in conservation biology, biogeography and ecology: The distinction between – and reconciliation of – ‘predictive’ and ‘explanatory’ models

In many large-scale conservation or ecological problems where experiments are intractable or unethical, regression methods are used to attempt to gauge the impact of a set of nominally independent variables (X) upon a dependent variable (Y). Workers often want to assert that a given X has a major influence on Y, and so, by using this indirection to infer a probable causal relationship. There are two difficulties apart from the demonstrability issue itself: (1) multiple regression is plagued by collinear relationships in X; and (2) any regression is designed to produce a function that in some way minimizes the overall difference between the observed and predicted Ys, which does not necessarily equate to determining probable influence in a multivariate setting. Problem (1) may be explored by comparing two avenues, one in which a single best regression model is sought and the other where all possible regression models are considered contemporaneously. It is suggested that if the two approaches do not agree upon which of the independent variables are likely to be significant, then the deductions must be subject to doubt.