The underwater light field in the Bellingshausen and Amundsen Seas (Antarctica)

The underwater light field in the Bellingshausen andAdmundsen Seas was characterised using data collectedduring the R/V Polarstern cruise ANT XI/3, from12.1.94 to 27.3.94. The euphotic zone varied from 24to 100 m depth. Spectral diffuse vertical attenuationcoefficients (K _d ())were determined for 12narrow wavebands as well as for photosyntheticallyavailable radiation (PAR, 400–700 nm): K _d (490)ranged from 0.03 to 0.26 m¹; K _d (550) from0.04 to 0.17 m¹; K _d (683) from 0.04 to0.17 m¹; and K _d (PAR) varied from 0.02 to0.25 m¹. K _d () for wavelengths centred at412 nm, 443 nm, 465 nm, 490 nm, 510 nm, 520 nm and550 nm were significantly correlated with chlorophyllconcentration (ranging from 0.1 to 6 mg m³). Thevertical attenuation coefficients for 340 nm and380 nm ranged from 0.10 to 0.69 m¹ and from 0.05to 0.34 m¹, respectively, and were also highlycorrelated with chlorophyll concentrations. These K _d values indicate that the 1% penetration depthmay reach maxima of 46 m and 92 m for 340 nm and380 nm, respectively. The spectral radiancereflectances (Rr()) for 443 nm, 510 nm and 550 nmwere less than 0.01 sr¹. Rr() for 665 nm and683 nm increased with depth up to 0.2 sr¹ because ofchlorophyll fluorescence. Using a model that predicts downwardirradiances by taking into account the attenuation bywater and absorption by chlorophyll, we show thatchlorophyll fluorescence has a significant influenceon the red downward irradiance (E _d (633, 665, 683))in deeper layers. The ability of the phytoplanktonpopulation to influence the light environment byautofluorescence and absorption processes depends onthe light conditions and on the photoacclimation ofthe cells, represented by the in vivo crosssection absorption coefficient of chlorophyll (a*). Theobtained mean chlorophyll-specific light attenuationcoefficients of phytoplankton in situ (k _d ) are higherthan the in vivo absorption coefficient of chlorophyll,more than to be excepted from the scattering. a*(), m² mg chl¹, decreased due topackaging effect with increasing chlorophyllconcentrations.     

Effects of agar and agarose on VentTM DNA polymerase and Taq DNA polymerase

Summary We have studied the effects of agar and agarose on Vent DNA polymerase and Taq DNA polymerase. Agar strongly inhibited Vent DNA polymerase but only moderately inhibited Taq DNA polymerase. Such a difference may be due to the fact that the two polymerases belong to different structural families. When Vent DNA polymerase is used to amplify DNA from lambda plaques, agarose rather than agar is the solid medium of choice.     

AgNO3 increases type II callus production from immature embryos of maize inbred B73 and its derivatives

Incorporating 10 to 100 M AgNO₃ into Phytagel (0.2%) solidified N6 medium containing 1 mg/L 2,4-D, 100 mg/L casamino acids and 25 mM praline (N6 1-100-25) promoted type II callus production from cultured Zea mays L. immature embryos of FRB73, B73 X A188 and a proprietary B73 BC6 genotype. Under these conditions, approximately 15, 80 and 80% of the respective FRB73, B73 X A188 and B73 BC6 explants produced type II calli after 2 to 3 weeks incubation in the dark at 28 C. In the absence of AgNO₃, the type II culture response from B73BC6 immature embryos was 25% on N6 1 100-25 solidified with Phytagel (0.2%) as compared to 0% for that solidified with 0.8% agar. Duncan's medium was tested using 10 to 100 m AgNO₃ and generally promoted type I callus initiation, although up to 6% of the explants produced type II cultures in the presence of 0.2% Phytagel. Ethylene emanation rates of up to 370 and 115 nL g-1 h-1 were detected from B73 X A188 immature embryos and calli, respectively, cultured on N6 1-100-25.     

Purification of macrolide 2′-phosphotransferase fromStreptomyces coelicolor Müller

Summary An enzyme that catalyzes 2-O-phosphorylation of oleandomycin and several other macrolide antibiotics has been purified approximately 47-fold from cell-free extracts ofStreptomyces coelicolor Müller, NRRL 3532 (UC 5240). The reaction product was verified as being oleandomycin-2-O-phosphate by mass spectrometry. As a result of purification, the enzyme was separated from two lincosaminide inactivating enzyme activities also present in the cell-free extract.     

Absorption of circularly polarizedγ-radiation in L- and D-amino acids

No difference within the experimental error ( 10³) was observed in the absorption of right- and left-circularly polarized-radiation in L- and D-tryptophan and tyrosine. For the measurements the 14.4 keV transition of⁵⁷Fe was used and the analysis of the circularly polarized-radiation was performed by Mössbauer method.     

Autotetraploid tangor plant regeneration from in vitro Citrus somatic embryogenic callus treated with colchicine

In vitro chromosome doubling of embryogenic callus lines of the Citrus cultivars Umatilla and Dweet tangors (Citrus reticulata Blanco×C. sinensis [L.] Osb.), Caffin clementine (C. clementina Hort. ex Tan.) and Wheeny grapefruit (C. paradisi Macf) was carried out in the presence of either 0.05 or 0.1% colchicine, or 0.01, 0.05 or 0.1% oryzalin. Embryogenic callus development was partly suppressed in the presence of colchicine, and completely suppressed by oryzalin at all concentrations tested. No plants were regenerated from any of the oryzalin treatments. Ploidy level of plants regenerated from the colchicine treatments was determined using flow cytometry and chromosome squashes. Three desirable non-chimeric, autotetraploid plants of the mono-embryonic cultivar Umatilla were produced using 0.05% colchicine and one from 0.1% colchicine. One mixoploid Dweet plant was produced using 0.1% colchicine.     

Aberrations in sexual behavior in some brewing and other industrial yeasts

Summary The mating behavior of a number of brewer's and distiller's yeasts was determined with a and haploid and aa and diploid tester strains. Mating frequencies were not high, ranging from one to (rarely) 2,000/10⁸ cells in the mating mixture. Sporulating hybrids were obtained in most matings, though the percentage spore viability initially obtained was often low. Notable the spore viability obtained in hybrids with the haploid tester strains and the brewing strains DIB and DICH was much higher than from the a haploid tester strain, and higher in hybrids between these strains and the aa diploid tester than in those from the tester strain. With the brewing strain NBA, the spore viability in hybrids with the a haploid tester strain was higher than in the case of strains DIB and DICH, but the spore viability in the hybrid of NBA x the haploid strain was higher still. The data are consistent with the hypothesis that with the a and aa tester strains, most of the industrial yeasts tested mate as diploids, and with the and testers, they mate as haploids, an hypothesis which is supported by the segregation of adenine markers in the progeny of these hybrids.Presented in part at the 6th International Specialized Symposium on Yeasts, Montpellier, France, 2–8 July, 1978     

LacSwitchTM Inducible Mammalian Expression System in mouse Swiss 3T3 fibroblasts

Swiss 3T3 fibroblasts were transfected with the provided plasmids of LacSwitch Inducible Mammalian Expression System (Stratagene). Stable transfectants were selected, expanded and characterised. At first, the production of CAT in these cell lines could be induced by IPTG treatment, but the inducibility was lost after a few months in culture in a reproducible manner. Further analysis revealed that the transfectants did not lose the cat gene nor the lac repressor protein. As a result, we conclude that LacSwitch Inducible Mammalian Expression System needs further modification for use in Swiss 3T3 fibroblasts.     

Plant regeneration capacity of callus derived from leaf,stem, and root segments of Populus alba L. x P. grandidentata Michx.

Summary Expiants for establishing callus cultures originated from in vitro cultured hybrid poplar (Populus alba L. X P. grandidentata Michx.). Plant regeneration was achieved from established callus cultures derived from stem internodes (SI), leaf discs (LD), and root segments (RS). Shoot regeneration from callus occurred within 4 weeks of culture on most of the media tested. Frequency of shoot formation was greatly increased by subculturing the selected organogenic calli on regeneration media. The highest rate of multiple shoot formation (an average number of 7/SI, 11/LD, and 8/RS) was obtained by using 0.05 M IBA in combination with 22.5 M 2iP, 22.5 M zeatin, and 12.5 M 2iP, respectively. Regenerated shoots were easily rooted in polyterra peat plugs in transparent plastic boxes. The rooted plantlets were subsequently transferred to pots containing an artificial potting mix.Abbreviations BA 6-benzylaminopurine - 2iP N⁶-isopentenyladenine - Z zeatin - 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indole-3-butyric acid - WPM Woody Plant Medium - PGR Plant Growth Regulator Journal Paper No. J-14119 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA, Project No. 2210     

Glycogen phosphorylase ‘b’ in Dictyostelium: stability and endogenous phosphorylation

Summary The slime mold Dictyostelium discoideum has two forms of the enzyme glycogen phosphorylase. The inactive phosphorylase b form requires 5 AMP for activity and is present in early development. The active phosphorylase a form is 5 AMP independent and occurs during later development. We here show that the 92 kd b enzyme subunit exists either as a singlet or a doublet upon SDS-PAGE, depending on the method of sample extraction. In the presence of exogenously added Mn²⁺ and ATP, the phosphorylase b shows apparent conversion into a 5 AMP independent form as measured by enzyme activity. In addition, Mn²⁺ and ATP also support an in vitro phosphorylation of the 92 kd phosphorylase b subunit. We also demonstrate phosphorylation of the b enzyme subunit in vivo by ³²-P incorporation into the enzyme protein. A protein kinase responsible for the observed in vitro phosphorylation of the phosphorylase b subunit is characterized.     

Partial mispairing and crossing-over between β0 and δ genes as the origin of the δ β0 thalassemia gene

Summary Two double heterozygous ⁰/⁰ thalassemic sibs of Mexican descent were studied. The father had a ⁰/⁰ genotype, while the mother, one sib and several maternal relatives were ⁰/⁰ heterozygotes. Parental consanguinity and an apparently low frequency of thalassemia among Mexicans suggested a possible common origin of both ⁰ and ⁰ genes. A hypothesis to explain such a possibility is proposed on the basis of a partial mispairing between ⁰ and genes followed by a crossing-over which would results in a ⁰ recombinant gene. This hypothesis could also be extended to explain the 22 gluala, 22 alaglu and 116 arghis Hb variants as recombinants from double crossing-over between and mispaired genes for which the name interstitial-Lepore is proposed.     

The catalysis of nucleotide polymerization by compounds of divalent lead

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

Plant regeneration from Citrus protoplasts: Variability in methodological requirements among cultivars and species

Summary Nucellar callus lines were established from two orange cultivars (Nucellar Shamouti, Shamouti Landau), three mandarin cultivars (Murcott, Dancy, Ponkan) one grapefruit cultivar (Duncan) and sour orange (Citrus aurantium). These callus lines were initiated from in vitro cultured ovules of young fruits and maintained an embryogenic capacity. The plating efficiencies of protoplasts derived from these calli, as well as those of protoplasts from lemon (cv. Villafranca) nucellar callus were differentially affected by the maceration enzymes and by the sugars used as osmotic stabilizers. Plants with normal morphological features were regenerated from cultured protoplasts derived from each of the nucellar callus lines. The establishment of eight new protoplast systems in Citrus paves the way for cell genetics studies and for novel breeding approaches in these economically important orchard trees.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. E-290, 1981 series     

Protocol-dependence of equivalent circuit parameters of toad urinary bladder

Summary Determinations of current-voltage relationships are widely employed in the characterization of epithelial sodium transport. In order to determine the protocol dependence of transport parameters in the toad urinary bladder, studies were carried out in the presence and absence of amiloride, an inhibitor of active sodium transport. With symmetric positive and negative perturbations of the transepithelial electrical potential difference (0±100 mV) for 30 sec, the amiloride-sensitive current-voltage (i ^a -) relationship was near linear over the range –75+100 mV, indicating constancy of the conductance ^a and the apparent electromotive force E _Na, lumped parameters of the standard electrical equivalent circuit model of the active transport system. With a reverse protocol (±1000 mV) or 15 min perturbations thei ^a - relationships were highly nonlinear. Nonlinearity reflected voltage dependence of parameters: perturbations that increased active transport decreased E _Na and increased ^a, as evaluated from 10 sec perturbations of ; slowing of active transport produced the converse changes. These effects are usefully analyzed in both quasi-steady states and true steady states by means of a detailed equivalent circuit incorporating the significant ionic currents across each plasma membrane. Precise understanding of the significance of ^a and E _Na will require characterization of the partial ionic conductances on perturbation of .     

Inheritance of callus formation ability in anther cultures of rice,Oryza sativa L.

Summary Inheritance of ability to form callus in rice anther culture was studied using the diallel technique. Anthers containing uninucleate microspores from two japonica cultivais (Minehikari and Taipei 309), two indica cultivars (Mingolo and Suweon 290), and 12 F₁'s of the diallel crosses involving these four parents were cultured on Chaleffs R₂ medium and evaluated for callus induction. The parents showed significant differences in anther callus formation, from 41.9% (Taipei 309) to 0% (Suweon 290). Callus induction ability was inherited as a recessive character conditioned by a single block of genes. Additive gene effects were predominant. The japonica types seemed to be good combiners for callus induction. The order of dominance among the four parents was Suweon 290, Mingolo, Minehikari and Taipei 309.     

In Vitro Modification of Sex Expression in Mulberry (Morus Alba) by Ethrel and Silver Nitrate

This paper compared the behavior of a diverse set of wheat genotypes in their tissue culture response. Significant differences were detected in plant regeneration, culture efficiency, and regeneration capacity when mature embryos of 47 wheat cultivars, breeding lines, and the common wheat progenitors, Triticum monococcum, T.tauschii, and Aegilops speltoides were compared. Although not currently used in wheat tissue culture, mature embryo-derived callus of cv. Zak (SWS), Scarlet (HRS), Tara (SWS), Jagger (HRW), UC 1036 (HRS), and Kyle durum showed better or comparable plant regeneration than commonly cultured cultivars Fielder and Bobwhite. Of the three diploid wheat progenitors tested, Ae. speltoides regenerated the most plants. In one replicated experiment, callus induction was correlated with culture efficiency (r = 0.42; p = 0.002) and regeneration capacity (r = 0.39; p = 0.002), and in a second larger screen, callus induction correlated with the total number of plants regenerated (r = 0.6; p = 0.001. Immature and mature embryos of Bobwhite and Crocus were compared for callus induction and plant regeneration. Immature embryos were superior explants in terms of plant regeneration. However, sufficient numbers of plants can be regenerated from mature embryos saving on growth facility resources and time required for the collection of immature embryos.     

Transformation of Atriplex gmelini plants from callus lines using Agrobacterium tumefaciens

Atriplex gmelini plants were regenerated via organogensis from hypocotyl explants. Callus lines were induced from the hypocotyl explants on Linsmaier and Skoog (LS) medium supplemented with 1 M benzyladenine and 5 M -naphthaleneacetic acid in the dark. Shoots were regenerated from the callus lines on LS medium supplemented with 20 M thidiazuron and 0.1 M -naphthaleneacetic acid under a high-intensity light condition (450 mol m^–2 s^–1). The regenerated shoots were rooted on LS medium without growth regulators to obtain fully developed plants. We succeeded in transforming Atriplex gmelini from callus lines using Agrobacterium tumefaciens.     

Transformation of peas (Pisum sativum L.) using immature cotyledons

A reliable Agrobacterium tumefaciens-mediated transformation method has been developed for peas (Pisum sativum) using immature cotyledons as the explant source. Transgenic plants were recovered from the four cultivars tested: Bolero, Trounce, Bohatyr and Huka. The method takes approximately 7 months from explant to seed-bearing primary regenerant. The binary vector used carried genes for kanamycin and phosphinothricin resistance. Transformed pea plants were selected on 10 mg/l phosphinothricin. The nptII and bar genes were shown to be stably inherited through the first sexual generation of transformed plants. Expression of the phosphinothricin-resistance gene in the transformed plants was demonstrated using the Buster (=Basta) leaf-paint test and the phosphinothricin acetyl transferase enzyme assay.Abbreviations BA 6-benzylaminopurine     

Somatic embryogenesis,plant regeneration and somaclonal variation in barley

In vitro culture of immature embryo and young leaf tissues was carried out with five cultivars of barley, Hordeum vulgare. Two cultivars (Albacete and Porthos) responded poorly from both types of explants, while the three others (Dissa, Golden Promise and Ingrid) produced a high frequency of embryogenic callus from these explants (25–60%). For Dissa and Ingrid, young leaf explants were slightly better than immature embryo explants for embryogenic callus induction, while immature embryo cultures of Golden Promise responded better than young leaf explants. Thus, there appears to be a significant genotype × explant interaction in the initiation of embryogenic callus in barley.Some phenotypic variants were detected among the regenerated plants of Golden Promise and Ingrid, most originating by epigenetic changes. Only in one case was the variant phenotype heritable, probably due to a mutation in the chloroplast DNA. Mitotic alteractions were not detected. Consequently, somaclonal variation did not appear to be a very frequent event in plants regenerated from 1- to 6- month-old cultures of barley.