Phyto- and protozooplankton biomass during austral summer in surface waters of the Weddell Sea and vicinity

Summary Phyto- and protozooplankton were sampled in the upper 10 m of the water column in austral summer during a cruise of RV Polarstern from January 6 to February 20 1985 in the eastern Bransfield Strait vicinity and in the northern, southeastern (off Vestkapp, twice: I and II) and southern Weddell Sea (Vahsel Bay across the Filchner Depression to Gould Bay). The plankton assemblages are discussed in relation to physical, chemical and biological factors in the different geographical areas in summer. Phytoplankton biomass (Phytoplankton carbon, PPC) ranged from 4–194 g carbon/l and consisted on average of 65% diatoms and 35% autotrophic flagellates. Whereas in the northwest phytoplankton assemblages were dominated by small nanoflagellates (78% of PPC), higher biomass of diatoms (54–94% of PPC) occurred at the other sampling sites. In general autotrophic flagellates and small pennate diatoms dominated at oceanic stations; in neritic areas large centric diatoms prevailed. Chlorophyll a concentrations ranged from 0.25–3.14/g chl a/l with a mean of 1.13/gmg chlorophyll a/l and an average phytoplankton carbon/chlorophyll a ratio of 39. Protozooplankton biomass (Protozooplankton carbon, PZC) ranged from 0–67 g carbon/l and consisted of 49% ciliates, 49% heterotrophic dinoflagellates and 2% tintinnids. Heterotrophic dinoflagellates were more important in the northern investigation areas (58%–84% of PZC). Ciliates dominated the protozooplankton in the southeast and south (56%–65% of PZC); higher abundances of tintinnids were observed only in the south (11% of PZC). The most remarkable feature of the surface waters was the high protozooplankton biomass: protozooplankton amounted to 25% on an average of the combined biomass of PPC plus PZC for the entire investigation period. Protozoan biomass in the southeastern and southern Weddell Sea occasionally exceeded phytoplankton biomass. Temperature, salinity, and inorganic nutrients were generally lower in the southern regions; at most of these stations a meltwater layer occurred in the upper meters of the water column. We suggest that this physical regime allows a well developed summer system with a high proportion of heterotrophic microplankton. In the eastern Bransfield Strait, in the northern Weddell Sea and close to the coast off Vestkapp (I), however, early summer conditions occurred with less protozooplankton contribution.Contribution no. 427 from the Alfred-Wegener-Institute for Polar and Marine Research     

A segment of rye chromosome 1 enhances growth and embryogenesis of calli derived from immature embryos of wheat

Summary The influence of the short arm of rye chromosome 1 (1RS) from Secale cereale var. Imperial on the growth and differentiation of callus cultures from wheat Triticum aestivum var. Chinese Spring immature embryos was analysed. This chromosome arm was found to stimulate both embryogenesis and the rate of growth of calli. Recombinant lines carrying segments of 1RS were used to delineate the regions of 1RS responsible for the tissue culture effects. The enhancement of embryogenesis and the stimulation of growth were shown to be associated with two distinct genetic regions of the chromosome arm; the former is located between the centromere and the Sec 1 locus, while the latter is situated in the immediate vicinity of the Sec 1 locus.     

Optomotor reaction and fixation of walking colorado beetles (Coleoptera: Chrysomelidae): Course control aspects

The paths of Colorado beetles (Leptinotarsa decemlineata Say)in a featureless environment are circular. This behavior is explained by an internal asymmetry. To stabilize the path, the fixation reaction or the optomotor response must work against this asymmetry. The turning behavior was examined in stationary patterns of vertical stripes different at spatial wavelengths (). The internal asymmetry was tested in a horizontally striped pattern. A stable fixation reaction was found only for 120 °. The results suggest that larger intrinsic turning tendencies shifts the stable point of the fixation reaction. The same vertically striped patterns were rotated to examine the following reaction of the beetle. It is concluded that the fixation component of the response of these insects, in particular, does not differ in the two situations.     

Biological activity of alpha-alkyl-amino acids

Summary A series of alpha-alkyl-amino acids were tested for some biological functions in the mouse (OF-1 Himberg) by adding them to the animal chow (30 mg/kg/day) for a period of six weeks. No differences in fluid or food uptake could be observed during the feeding period, as compared to a control group. Histology of liver and kidney did not show any changes. Testing routine clinical chemical parameters (serum substrates and enzymes) revealed the following changes: Hex-Ala and But-Abu increased the serum glucose levels. But-Abu dramatically lowered the triglycerides. Serum albumin was increased by Pent-Ala, Me-Val, and But-Abu. LDH was inhibited by But-Abu.     

Nitrate levels affect the development of the black locust-Rhizobium symbiosis

Summary Experiments with black locust (Robinia pseudoacacia L.) seedlings grown under strictly controlled laboratory conditions indicated that the availability of nitrate has a marked impact on nitrogen fixation. When nitrate concentrations were very low, both nodulation and seedling growth were impaired, whereas nitrate concentrations high enough to promote plant growth strongly inhibited symbiotic nitrogen fixation. When nitrate was added to the growth medium after infection, nodulation and nitrogen fixation of the seedlings decreased. This effect was even more marked when nitrate was applied before infection with rhizobia. Higher nitrogen concentrations also reduced nodule number and nodule mass when applied simultaneously with the infecting bacteria. The contribution of symbiotic nitrogen fixation to black locust shoot mass by far exceeded its effects on shoot length and root mass. When nitrate availability was very low, specific nitrogen fixation (i. e. nitrogenase activity per nodule wet weight) was improved with increasing nitrogen supply, but rapidly decreased with higher nitrogen concentrations.     

Immunohistochemical demonstration of villin in the normal human pancreas and in chronic pancreatitis

Summary Human pancreatic tissue was investigated by immunohistochemistry using a polyclonal antibody against the actin binding protein villin, which participates in the formation of actin filament bundles in the microvilli. In cells of the different parts of the pancreatic duct system as well as in the acinar cells villin immunoreactivity was located mainly at the apical cell surface. This was confirmed by the ultrastructural demonstration of microvilli on the surface of duct and acinar cells, which exhibited the typical actin bundles. In chronic pancreatitis the staining for villin in duct-like structures of degenerative pancreatic tissue was irregular or even absent. This correlated with the electron microscopic observation of duct-like structures known as tubular complexes composed of cells devoid of microvilli at the apical cell surface. At the light microscopical level degenerative structures without lumen and of unknown origin showed a strong staining for villin at their basal cell surface.     

The clinical significance of HAMA in patients treated with mouse monoclonal antibodies

Twenty-four patients were analyzed for the development of HAMA (human antimouse antibodies) after being treated with repeated doses (200–500 mg) of the mouse monoclonal antibody (MAb) 17-1A. All patients developed anti-17-1A IgG antibodies, and most of them also developed IgM antibodies. In only two patients could immune complexes be demonstrated. Allergic reactions were rare (1.9%). In an extended study, a further 19 patient were analyzed for an idiotypic response. Forty-one out of 43 patients developed antiidiotypic antibodies (ab₂), and 20 of these also antianti-idiotypic antibodies (ab₃). Ab₃ ⁺ patients responded significantly better (p=0.01) and survived longer (p<0.001) compared to ab₃ ⁻ patients. In this study, we showed that MAb 17-1A could be repeatedly given on a safe basis. The development of high titers of HAMA did not cause significant clinical problems when further repeated infusions of MAb 17-1A were given. The development of an idiotypic response also indicate that the induction of HAMA might be beneficial and not harmful to the patient.     

Biosurfactant yields and nutrient consumption of Pseudomonas fluorescens 378 studied in a microcomputer controlled multifermentation system

Production of biosurfactant AP-6 and consumption of carbon (succinic acid) and nitrogen (ammonium ions) by Pseudomonas fluorescens 378 were studied under different growth conditions. The study was performed in a microcomputer controlled multibatch fermentation system which enabled simultaneous running of 10 fermentors. The fermentors were mantled glass vessels, temperature controlled by circulated water, and mixing was arranged by magnetic stirrers. They were connected to the computer system (pH measurement and control) via signal conditioning cards. The microcomputer had a 128 kbytes RAM, two 800-kbyte floppy disc drives, a graphic terminal, and expansion cards. Biosurfactant production was independent of the carbon-to-nitrogen ratio and the phosphorus content in the medium. Omitting the Fe(III) supplement to the medium increased the product yield by 120%. Changes in oxygen transfer rate and pH in the iron deficient cultures did not have any effect on the product yield. Iron deficiency increased the cell consumption of carbon source. Consumption of carbon source in relation to nitrogen uptake (carbon/nitrogen quotient) increased with increasing quotient in the growth medium. The uptake of carbon and nitrogen changed in the intervals of 1.2-1.5 g/g biomass and 0.09-0.16 g/g biomass, respectively. The consumption of carbon increased from 1.5 g/g biomass to 2.0 g/g biomass when the medium concentration of phosphorus was decreased from 0.18 to 0.027 g/L.     

Genomic clones of a wild-type allele and a transposable element-induced mutant allele of the sucrose synthase gene of Zea mays L

In an attempt to isolate the transposable genetic element Ds from Zea mays L., we cloned DNA fragments hybridizing to a cDNA clone derived from the sucrose synthase gene in a λ vector (λ::Zm Sh). The fragments cloned from wild-type and from the Ds-induced mutant sh-m5933 (λ::Zm sh-m5933) share a segment 6 kb long while a contiguous segment of 15 kb of λ::Zm sh-m5933 (mutant-derived DNA) does not hybridize to the DNA segment cloned from the wild-type. Restriction maps are given, and the junction point between the two DNA segments in the mutant clone was determined. Hybridization of DNA fragments, present in the wild-type DNA of λ::Zm Sh, but not in the mutant clone, λ::Zm sh-m5933, to genomic DNA of sh-m5933 showed that no part of this DNA is deleted. It cannot be said whether the DNA found in the mutant, but not in the wild-type clone, has been brought there by Ds insertion or by another Ds-dependent DNA rearrangement. The mutant-derived DNA was hybridized to genomic DNA of various maize lines digested by several restriction endonucleases. Approximately 40 bands were detected. The mutant-derived DNA contains two pairs of inverted repeats several hundred nucleotide pairs long, one of which is located at the junction to wild-type-derived DNA.