Two types of calcium-dependent channels of potassium outward current in the somatic membrane of Helix pomatia neurons

Characteristics of delayed potassium outward current were investigated during voltage clamp experiments on nonidentified intracellularly perfused neurons isolated from the snailHelix pomatia. A calcium-dependent potassium curent displaying special properties was shown to exist, apart from the voltage-operated potassium currents dependent on intracellular calcium ions . This type of current increases with a rise in the extracellular concentration of calcium ions , is not blocked by intracellular application of 10 mM EGTA and 77 mM fluoride, and may be suppressed by adding 1.5 mM cobalt ions to the extracellular fluid. This current, unlike , only takes a few milliseconds to peak, after which it fades to a steady level, comparable with that of .A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 2, pp. 185–191, March–April, 1987.     

Reciprocal inhibition of human motoneurons with different firing frequencies

A study was made of the effect of reciprocal inhibition on individual firing motoneurons in the extensor carpi ulnaris and soleus muscle in human subjects. Peristimulus histograms (PSH) were plotted at different average frequency of motoneuron firing ( ) and the change in duration of interspike intervals (ISI) was analyzed. For reciprocal inhibition, as for other types of inhibition, is a factor in the effectiveness of motoneuron inhibition. The duration of inhibition apparent in the PSH, the sizes of zones of inhibition effectiveness in the ISIs and lengthening of the intervals are dependent on . For all motoneurons, the low range is most favorable for effective inhibition. The dependence of effectiveness of a volley on the time of its arrival within the ISI is also analyzed.Institute for Problems of Information Transmission, Russian Academy of Sciences, Moscow. Translated from Neirofiziologiya, Vol. 24, No. 6, pp. 643–653, November–December, 1992.     

Decrease in maximal sodium permeability and slow sodium inactivation produced by trimecaine in the Ranvier node

The action of trimecaine on sodium permeability of the membrane was studied by the voltage clamp method in single nodes of Ranvier. Like procaine, trimecaine was shown to reduce maximal sodium permeability ( _Na) and to induce slow sodium inactivation. The slow inactivation arising in the presence of trimecaine was qualitatively very similar to that observed during the action of procaine or a high external potassium concentration. Dose-effect curves were obtained for _Na and slow inactivation and they showed that one molecule of trimecaine reacts with one sodium channel in the mechanism of both these effects. The local anesthetic has greater affinity for the receptor responsible for slow inactivation (equilibrium constants about 0.3·10^–3 M for _Na and 0.2·10^–14 M for slow inactivation.A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 8, No. 4, pp. 418–425, July–August, 1976.     

Breeding success, nestling diet and parental care in the White-backed WoodpeckerDendrocopos leucotos

In western Norway, pairs of White-backed Woodpecker breeding in coastal areas (<2 km from the sea) started egg laying earlier than pairs in inland areas (2–15 km from the sea). Laying was earlier in years when the ambient temperature was higher during the pre-laying period. About half of 69 pairs studied started laying within the period 25–30 April over the 10 study years. Clutch size ( = 4.0 eggs) and breeding success values (fledglings per egg; = 0.63) did not differ between years. The mean number of fledglings per nest was 2.4. The mean body mass of fledglings differed between years and were negatively correlated with the laying date. Fledgling mass differed between sexes (males = 87.8g, females = 84.2g), and both sexes were heavier in coastal than in inland areas. The mean hourly feeding rate of nestlings increased with nestling age, but feeding rate per nestling did not vary with nestling number. The nestling food was mainly comprised by wood-living beetle larvae ( = 72% by dry mass). It is suggested that breeding success is related to territorial quality, which, in turn, strongly influences female quality.

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Zusammenfassung In Westnorwegen beginnen Weißrückenspechte, die an der Küste brüten, eher mit der Eiablage als Paare im Inland (>2 km von der Küsten entfernt). Höhere Lufttemperaturen in der Vorlegezeit begünstigten frühere Eiablage. Mehr als die Hälfte der 69 untersuchten Paare begannen innerhalb von 10 Jahren zwischen 25. und 30. April mit der Eiablage. Gelegegröße ( = 4,0 Eier) und Bruterfolg (flügge Junge pro Ei; = 0,63) unterschieden sich nicht in einzelnen Jahren. Pro Nest flogen 2,4 Junge aus. Die mittlere Körpermasse der flüggen Jungvögel war mit dem Datum der Eiablage negativ korreliert. Flügge Männchen waren etwas schwerer als gleichalte Weibchen ( 87,9, 84,2 g); beide Geschlechter waren in Küstengebieten schwerer als im Inland. Die mittlere Fütterungsrate pro Stunde stieg mit dem Alter der Nestlinge, veränderte sich aber nicht mit der Zahl der Nestlinge. Die Nestlingsnahrung bestand vor allem aus holzbewohnenden Käferlarven ( = 72% der Trockenmasse). Vermutlich hängt der Bruterfolg mit der Qualität des Brutreviers zusammen, die wiederum vor allem die Kondition des Weibchens bestimmt.

     

Two new species of Isospora (Apicomplexa: Eimeriidae) from passeriform birds of South America

Summary Two new species of Isospora (Apicomplexa: Eimeriidae) are described from the faeces of passeriform birds of South America. I. cyanocoracis n. sp. is described from Cyanocorax chrysops (Passeriformes: Corvidae) and I. paroariae n. sp. from Paroaria coronata (Passeriformes: Emberizidae). I. cyanocoracis oocysts are spherical or subspherical, 28.7×26.8 m (25.0–30.5×24.5–29.0), with bi-layered wall about 2.0 m thick. Micropyle and oocyst residuum are absent; large polar granule present. Sporocysts are ovoid, 19.3×11.4 m (17.0–21.0×10.5–12.2), with smooth, single-layered wall about 0.8 m thick. Stieda and substiedal bodies and sporocyst residuum are present. Sporozoites 12.2×4.2 m (10.5–15.0×3.5–4.5), possess spherical anterior and posterior refractile bodies. I. paroariae oocysts are spherical or subspherical, 22.3×21.4 m (19.5–25.5×18.5–24.0), and have bi-layered wall about 1.8 m thick. Micropyle, polar granule, and oocyst residuum are absent. Sporocysts ovoid, 15.2×10.0 m (14.0–16.5×8.0–11.5), possess smooth, single-layered wall about 0.7 m thick. Stieda and substiedal bodies and sporocyst residuum are present. Sporozoites elongate, 11.3×3.4 m (10.0–13.5×3.2–4.0), have single, large, posterior refractile body. ac]19840712     

Activity and oxygen consumption during hypoxic exposure in high altitude and lowland sceloporine lizards

Summary Resting rates of O₂ consumption against , exercise endurance times and during recovery from vigorous exercise were measured inSceloporus occidentalis captured near sea level and inS. graciosus captured above 2850 m. Oxygen consumption against was also measured inS. occidentalis captured above 2850 m. When was recorded continuously, as ambient was slowly reduced from 155 Torr, it became directly dependent upon ambient between 110 and 120 Torr. The critical for the high altitude lizards was lower than that for the lowland lizards, which enabled the former to maintain relatively higher 's when ambient was reduced below 120 Torr. The high altitude lizards also had significantly greater endurance when stimulated to exercise at 1600 m ( 130 Torr). Both the higher under hypoxia and the greater endurance roughly parallel a significantly greater maximum in the high altitude lizards. At a simulated altitude of 3600 m ( 100 Torr), maximum and rate of recovery of the O₂ debt calculated from post active were significantly reduced in the lowland but not the high altitude lizards. The effects of simulated altitude conditions on the lowland but not the mountaine animals indicate adaptations to altitude in these sceloporine lizards. We did not find any consistent relationship between organ/body weight ratios or hematocrit and our measures of endurance or the altitude at which the lizards were captured.     

Changes in Swallowing-Related Tachycardia and Respiratory Arrhythmia Induced by Modulation of Tonic Parasympathetic Influences

In 19 tested persons in the resting lying position, we examined changes in the mean duration of R-R intervals and in parasympathetic chronotropic cardiac reactions (respiratory arrhythmia,RA, and swallowing-related tachycardia, ST) induced by intensified tonic parasympathetic influences after peroral administration of antagonists of muscarinic (M) receptors in small doses. Administration of 0.02 g of an extract of Belladonna, which contains alkaloids of the atropine group, led to a significant increase (P < 0.001). In this case, the RA at the natural frequency of breathing (P < 0.05) and ST (P < 0.001) simultaneously increased. Close correlation was observed both between initial values of the ST and in various tested persons (r = 0.87) and between changes in these values, which were induced by the action of small amounts of M antagonists (r = 84). In various persons, the RA during deep slowed breathing (6 min^-1, RA₆) demonstrated ambiguous modifications. In the structure of RA₆, we identified two components: an inspiratory tachycardic (TC) and an expiratory bradycardic (BC). With intensification of the parasympathetic influences, the TC began to prevail; its increase was strongly related to a rise in the (r = 0.84). In contrast, correlation between changes in the BC and an increase in the was completely absent (r = 0.001). Therefore, small amounts of M antagonists intensify both the tonic component of parasympathetic control (increasing the ) and its dynamic indices, the magnitudes of the ST and RA. Tachycardia during swallowing and the inspiratory TC under conditions of deep slowed breathing are closely related to changes in the parasympathetic influences. The magnitude of the RA is the index, which reflects the tonic component of chtonotropic control under conditions of both slowed and natural breathing less adequately than the ST.     

Changes of cytoplasmic free Ca2+ in the green alga Mougeotia scalaris as monitored with indo-1, and their effect on the velocity of chloroplast movements

The fluorescent calcium-sensitive dye 1-[2-amino-5-(6-carboxyindol-2-yl)-phenoxy]-2-(2-amino-5-methylphenoxy)-ethane-N,N,N,N-tetraacetic acid (indo-1) was loaded by a transplasmalemma pH gradient into filamentous cells and protoplasts of Mougeotia scalaris, such that most of the indo-1 fluorescence originated from the cytoplasm. Incubation of M. scalaris filaments in ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid (EGTA)-buffered media (-log [Ca²⁺] (=pCa) 8 versus pCa 3) caused a consistent and significant decrease in the cytoplasmic free [Ca²⁺]. Pulses of the fluorescence excitation light (UV-A 365 nm, 0.7 s) caused an increase in cytoplasmic free [Ca²⁺] in M. scalaris that was nearly independent of the external [Ca²⁺] and of chloroplast dislocation by centrifugation. This calcium flux, highest in UV-A light, compared with blue or red light, probably resulted from a release of Ca²⁺ from intracellular stores. Increased cytoplasmic [Ca²⁺] may affect the velocity of chloroplast rotation since UV-A-light-mediated chloroplast movement was faster than in blue or red light. Consistently, the calcium ionophore A23187 and the calcium-channel agonist Bay-K8644 both increased the velocity of the red-light-mediated chloroplast rotation. Based on these and other observations, a Ca²⁺-induced decrease in cytoplasmic viscosity in Mougeotia is presumed to occur.Abbreviations EGTA ethylene glycol-bis-(-aminoethyl ether)N,N,N,N-tetraacetic acid - indo-1 1-[2-amino-5-(6-carboxyindol-2-yl)-phenoxy]-2-(2-amino-5-methylphenoxy)-ethane-N,N,N,Ntetraacetic acid - pCa log [Ca²⁺] - P_fr far-red-absorbing form of phytochrome - P_r red-absorbing form of phytochrome - x_G geometric mean Dedicated to Professor Wolfgang Haupt on the occasion of his 70th birthdayThis paper is part of the Ph.D. thesis of U. Russ at the Justus-Liebig-Universitat Giessen (FRG). Part of this work has been presented at a meeting on Calcium and intracellular signalling in plants in Plymouth, UK, Dec. 1990We are indebted to Dr. G. Seibold and Dipl. Phys. H. Weintraut for their advice on the technique of microspectrofluorometry and for allowing access to the microspectrophotometric facilities in the Strahlenzentrum der Justus-Liebig-Universität, Giessen, FRG. We thank Mrs. A. Quanz for reliable culture of the algae and evaluation of the videotapes. Bay-K8644 was a generous gift of Bayer AG, Wuppertal, FRG. U. russ was supported by a scholarship according to the Hessisches Graduierten Förderungsgesetz. This work was supported by the Deutsche Forschungsgemeinschaft.     

Functional diversity and community structure of microorganisms in rhizosphere and non-rhizosphere Canadian arctic soils

Functional diversities of microorganisms in arctic soil samples at three incubation temperatures were assessed using sole-carbon-source-utilization (SCSU). Soil samples from four sites were collected from the rhizosphere and non-rhizosphere soils. Microorganisms were extracted from samples and inoculated into ECO-Biolog plates and incubated at 4, 10 and 28 °C. Calculations of Shannon–Weaver diversity and Shannon–Weaver evenness were based on the substrate utilization in the Biolog plates. Shannon–Weaver diversities (H) in rhizosphere samples were significantly greater ( _H = 3.023 ± 0.197; P < 0.005) than in non-rhizosphere samples ( _H = 2.770 ± 0.154). Similarly, the evenness (E) of the inoculated microbial cells exhibited significant differences (P < 0.005) between the rhizosphere and non-rhizosphere soil samples ( _E = 0.880 ± 0.057 for soils with rhizosphere; _E = 0.807 ± 0.044 for non-rhizosphere samples). Higher microbial diversity and evenness were observed in samples incubated at 4 °C than at 28 °C [least significant difference (lsd) = 0.29], and evenness indices were higher in rhizosphere samples than in non-rhizosphere soils incubated at all three temperatures (lsd = 0.02). Principal component analysis (PCA) of the multivariate data set differentiated the soil samples on the relatively gross scale of microbial communities isolated from rhizosphere and non-rhizosphere soils at all three temperatures.     

Gross nitrogen transformations in soils from uncut and cut boreal upland and peatland coniferous forest stands

Gross and net nitrogen (N) ammonification and nitrification were measured in soils from an uncut and recently cut upland and peatland conifer stand in northwestern Ontario, Canada. Rates of gross total inorganic N immobilization were similar to gross mineralization, resulting in low net mineralization rates in soils from all four upland and peatland conifer stands. Gross ammonification rates were variable but similar in soils from uncut and cut peatland hollows (18–19mgNkg^–1day^–1) and upland forest floor soils (14–19mgNkg^–1day^–1). Gross ammonium ( ) immobilization rates were also variable but similar to ammonification rates. Median gross nitrification rates were within 0–2mgNkg^–1day^–1 in soils from all four upland and peatland cut and uncut stands, although rates were consistently higher for the soils from the cut stands. Large variability in gross nitrification rates were observed in peatland soils, however the highest gross nitrification rates were measured in saturated peatland soils. Net rates remained low in the soils from all four stands due to high nitrate ( ) immobilization and very fast turnover (<0.2 day). Our results suggest that potential losses may be negated by high immobilization in uncut and cut boreal forest stands. This study reveals the potential for the interaction of N production and consumption processes in regulating N retention in upland and peatland conifer forests, and the resilience of the boreal forest to disturbance.     

EEG Activity in the Process of Measuring-off of Time Intervals by Humans

We recorded EEG from sites C3 and C4 in an experimental situation with internal counting-off of a 20-sec-long time interval, whose beginning and end were limited by the tested subject by pushing a button; 65 adult men and women took part in the tests. In the first experimental series, the subject obtained no real information on the accuracy in production of the interval. In the second series, such information was displayed by feedback visual signals. We calculated means of the measured intervals ( ), coefficient of variation of the realizations (CV), and, in the series with the real feedback, successfulness of measuring-off (normalized number of fits within an acceptable range of the standard interval, 19 to 21 sec). Analysis of the data obtained in the first experimental series for the entire tested group demonstrated the existence of a reverse dependence between the modal frequency of EEG beta rhythm recorded from the left hemisphere in the course of measuring-off of the interval and the value. In the second series, we found significant negative correlation between the beta rhythm power in both hemispheres and CV, that between the alpha rhythm power in the left hemisphere and , and positive correlation between the alpha rhythm frequency in the left hemisphere and successfulness of the interval counting-off. Analysis of the dynamics of EEG of each tested subject demonstrated the existence of mostly reverse dependences between the powers of a few EEG rhythms and duration of the produced interval. We hypothesize that the frequencies of the alpha and beta EEG oscillations play the role of significant indices reflecting the speed of the internal clock of the individual. We also emphasize the complex nature and the high individual variability of the EEG pattern in the course of measuring-off of time intervals.     

Reversed bohr and root shifts in hemocyanin of the marine prosobranch,Buccinum undatum: Adaptations to a periodically hypoxic habitat

Summary Oxygen binding properties of the hemocyanin-containing blood ofBuccinum undatum were examined in vitro and in vivo under normoxic ( 150 mmHg) and hypoxic ( 50 mmHg) conditions at 10°C. Blood pH and showed a decrease in vivo under hypoxic conditions. Oxygen uptake at high water , was about 18 ml O₂/kg·h (wet weight) and the critical oxygen tension between 25 and 50 mm Hg. In vitro the O₂ binding to hemocyanin showedn-values independent of pH, while both O₂ affinity and oxygen carrying capacity were strongly pH dependent. Oxygen affinity increased below pH=8.1 and thus showed a pronounced reversed Bohr shift in the physiological pH range (7.5<pH<8.1). The oxygen carrying capacity similarly increased markedly with falling pH in the physiological pH range (reversed Root shift). Astrup titration curves showed a metabolic and respiratory acidosis under hypoxic conditions ( 50 mm Hg). The role of hemocyanin in the transport of oxygen in relation to ambient O₂ availability is discussed.     

Characterization of microbial NO production, N2O production and CH4 oxidation initiated by aeration of anoxic rice field soil

Intermittent drainage of rice fields isdiscussed as an option to mitigate emission ofCH₄, an important greenhouse gas. HoweverN₂O, a potentially more effective greenhouse gas,may be emitted during the aeration phase. Therefore,the metabolism of NO, N₂O, NH ,NO and NO and the kinetics ofCH₄ oxidation were measured after aeration ofmethanogenic rice field soil. Before aeration, thesoil contained NH in relatively highconcentrations (about 4 mM), while NO andNO were almost undetectable. Immediatelyafter aeration both NO and N₂O were produced withrates of about 15 pmol h^-1 gdw^-1 and 5 pmolh^-1 gdw^-1, respectively. Simultaneously,NH decreased while NO accumulated. Later on, NO was depletedwhile NO concentrations increased.Characteristic phases of nitrogen turnover wereassociated with the activities of ammonium oxidizers,nitrite oxidizers and denitrifiers. Oxidation ofNH and production of NO and N₂O wereinhibited by 10 Pa acetylene demonstrating thatnitrification was obligatory for the initiation ofnitrogen turnover and production of NO and N₂O.Ammonium oxidation was not limited by the availableNH and thus, concomittant production of NOand N₂O was not stimulated by addition ofNH . However, addition of NO stimulated production of NO and N₂O in bothanoxic and aerated rice soil slurries. In this case,10 Pa acetylene did not inhibit the production of NOand N₂O demonstrating that it was due todenitrification which was obviously limited by theavailability of NO . In the aerated soilslurries CH₄ was only oxidized if present atelevated concentrations >50 ppmv CH₄). Atatmospheric CH₄ concentrations (1.7 ppmv)CH₄ was not consumed, but was even slightly produced.CH₄ oxidation activity increased afterpreincubation at 20% CH₄, and then CH₄was also oxidized at atmospheric concentrations. CH₄oxidation kinetics exhibited sigmoid characteristicsat low CH₄ concentrations presumably because ofinhibition of CH₄ oxidation by NH .     

On the innervation of mammalian endocrine glands (anterior pituitary and parathyroids)

Summary Electron microscopic studies have been carried out on the innervation of the mammalian anterior pituitary and parathyroids. The total area of grid squares (2.25·10^–2mm²) examined was 2000 per gland and species. In the pituitary pars distalis and in the parenchyma of the parathyroid gland we did not observe a single axon profile. According to the equation proposed by Hennig (1963) we have calculated that there might be—if any—0.133 mm of nerves per 1 mm³ tissue in those two endocrine glands (level of significance 0.95). Comparing these results to the degree of innervation in brown adipose tissue containing more than 160 mm nerve per 1 mm³ tissue we can not imagine that such a small degree of innervation is of any biological importance.In the pituitary pars tuberalis two types of axon terminals have been found both inside and outside the basement membrane surrounding the epithelial complexes. One type contains synaptic and two populations of smaller dense-cored vesicles, the other one contains a population of larger granules which have some properties of the classical elementary granules. Further investigations have to clarify the functional significance of those nerve endings.This investigation was supported by the Deutsche Forschungsgemeinschaft.     

Influence of plant growth regulators,basal media and carbohydrate levels on the in vitro development of Pinus ponderosa (Dougl. ex Law.) cotyledon explants

Applications of in vitro screening techniques for Pinus ponderosa resistance to Peridermium harknessii could be beneficial in a tree breeding program. Plant growth regulators, basal media formula and carbohydrate levels were examined to determine the various effects each would have on excised cotyledon growth and development. Proliferating green callus was initiated from cotyledon explants on SH basal medium containing 4.4 M BA:5.4 M NAA and 1% sucrose. Subsequent subculturing onto LS medium supplemented with 44.0 M BA: 5.4 M NAA and 2% sucrose improved callus maintenance. The highest frequency of caulogenesis from cotyledon explants occurred on a modified GD medium containing 44.0 M BA: 0.054 M NAA and 4% glucose. The influence of nitrogen source, osmoticum and medium salt concentrations are discussed relative to callus initiation and caulogenesis.Abbreviations BA 6-benzyladenine - NAA -naphthaleneacetic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - 2,4-D 2,4-dichlorophenoxyacetic acid - CD Campbell & Durzan - GD Gresshoff & Doy - LP Le Poivre - LS Linsmaier & Skoog - MC McCown - SH Schenk & Hildebrandt     

Spondyloepiphyseal dysplasia tarda: linkage with genetic markers from the distal short arm of the X chromosome

Summary A linkage study of six families with spondyloepiphyseal dysplasia tarda (SEDL) has been performed. A linkage to site DXS41 ( =0.08; =3.07) and DXS92 ( =0.05; =2.95) has been established. We propose, that the SEDL locus lies on the distal part of the short arm of the X chromosome.     

Evidence for linkage of the gene causing familial Mediterranean fever to chromosome 17q in non-Ashkenazi Jewish families: second locus or type I error?

Familial Mediterranean fever (FMF) is an autosomal recessive disorder of unknown pathogenesis, characterized by recurrent, selflimited attacks of fever with synovitis, peritonitis, or pleurisy. Using DNAs from affected Israeli families, we have recently mapped the gene causing FMF (designated MEF) to the short arm of chromosome 16, with two-point lod scores in excess of 20. In this report we consider the possibility of a second FMF susceptibility locus. Before discovering linkage to markers on chromosome 16, we had found suggestive evidence for linkage to chromosome 17q, with the following maximal two-point lod scores: D17S74 (pCMM86), = 2.47, ( = 0.20); D17S40 (pLEW101), = 2.15( = 0.15); D17S35 (CRI-pP3-1), = 1.78 ( = 0.15); D17S46 (pLEW108), = 1.69 ( = 0.18), D17S254, = 2.30 ( = 0.20). Moreover, multipoint linkage analysis using D17S74 and D17S40 as fixed loci gave = 3.27 approximately 10 centimorgans (cM) telomeric to D17S40. Data with the chromosome 17 markers alone in our families suggested locus heterogeneity. Nevertheless, our families were not separable into complementary subsets showing linkage either to chromosome 16 or to chromosome 17. We also examined the possibility that the positive lod scores for chromosome 17 might reflect a secondary, modifying locus. By several measures of disease severity, families with positive lod scores for chromosome 17 loci had no worse disease than those with negative lod scores for these loci. We conclude that chromosome 17 does not encode a major FMF susceptibility gene for some of the families, nor does it encode a disease-modifying gene. Rather, it would appear that linkage to chromosome 17 is a false positive (type I) error. These results reemphasize the fact that a lod score of 3.0 corresponds to a posterior probability of linkage of 95%, with an attendant 1 in 20 chance of observing a false positive.     

The nucleotide sequence ofBeneckea harveyi 5S rRNA

Summary The complete sequence of the 5S rRNA from the bioluminescent bacterium,Beneckea harveyi has been determined to be p U G C U U G G C G C C A U A G C G A U U-G G A C C C A C U G A (U) C U U C A U U C C-G A A C C A G A A G U G A A C G A A U U A-G G C C G A U G G U G U G U G G G G C U-C C C C A U G U A G A G U A G G A A U C G-C C A G G U (U)_OH.Two sites of sensitivity to ribonuclease T₂ cleavage were identified; at A₄₁ and either A₅₄ or A₅₅. Comparison with existing sequence information fromEscherichia coli andPhotobacterium phosphoreum clarifies the amount of diversity among the bioluminescent bacteria and provides further insight into their phylogenetic position. Sequence heterogeneities were encountered and the importance of these in interpreting 5S rRNA data is discussed.     

Estimating the Recombination frequency for the PTC-Kell linkage

Summary Two data sets are analyzed for linkage between the PTC and Kell blood group loci. The original report of close linkage for these loci was that of Conneally et al. (1976), where the maximum likelihood estimate of was 0.05. These two new data sets give a combined maximum likelihood estimate of _m=f =0.28. Estimating the recombination frequency for the sexes separately gave _m =0.29, _f =0.23. The combined maximum likelihood estimate over all published data sets including this report is _m=f =0.14, _max=8.94. There is statistically significant evidence of heterogeneity among the published studies.     

Dissecting subdomains involved in multiple functions of the CK2β subunit

We have characterized several subdomains of the subunit of protein kinase CK2. The N-terminal half of the protein exhibits a pseudo-substrate segment in tandem with a polyamine binding domain responsible for the activation of the kinase by these polybasic compounds. Study of the chemical features of this polyamine binding site showed that polyamine analogs exhibiting the highest affinity for CK2 are the best CK2 activators. Mutational analysis disclosed that glutamic residues lying in the polyacidic region of the CK2 subunit are involved in the interaction with polyamine molecules and allowed the delineation of an autonomous binding domain. Furthermore, this regulatory domain was shown to mediate the association of CK2 with plasma membrane.The C-terminal domain of the CK2 subunit plays a role in the oligomerization of the kinase since it was observed that a truncated form of this subunit lacking its 33-last amino acids was incompetent for the assembly of polymeric forms of CK2. Altogether, our results support the notion that the subunit of CK2 is a modular protein made by the association of interdependent domains that are involved in its multiple functions.