Plant diversity in late medieval cornfields of northern Switzerland

Weed assemblages from late medieval cornfields have been studied for the first time in northern Switzerland. Eleven samples from at least two different grain stores were investigated. The samples were collected from the carbonised remains of six wooden houses built in the late 13th century A.D. and which burnt down in the middle of the 15th century. The weed floras found in the spelt (Triticum spelta) and oats (Avena sativa) indicate a high botanical diversity in the cornfields at harvest time. Although oats are normally a summer crop and spelt a winter crop, both summer and winter crop weeds (as well as many different present-day grassland taxa) were found in each type of grain. Most of the weeds found were perennial plants, which was interpreted as an indication of both extensive tillage of the arable land and application of the three-field rotation system (Dreifelderwirtschaft). The spectra of the two palaeophytocoenoses (assemblages of ancient plant remains) studied suggest that the phytosociological method may not be reliable for classification of the late medieval remains into summer and winter crop weed communities. These findings should provide a better understanding of the development of anthropogenic plant communities, and in particular, the development of crop weed communities.     

Changes in LHβ-gene and FSHβ-gene expression in the ram pars tuberalis according to season and castration

Luteinizing hormone beta (LH) and follicle stimulating hormone beta (FSH) subunits and their mRNAs were studied in the ram pars tuberalis following different seasonal (winter vs summer) and experimental (intact vs castrated animals) conditions. Hormone-containing cells were identified by immunohistochemistry, and mRNAs for LH and FSH by in situ hybridization using homologous double-stranded ³⁵S-cDNAs. The labelling was quantified by image analysis. Immunohistochemical staining showed that cells containing LH and FSH were localized mainly in the ventral part of the pars tuberalis but that, in the summer, additional LH-containing cells were present in the dorsal part in intact rams. On the other hand, LH-mRNA labelling was found in the whole pars tuberalis in wethers but only in the ventral part in intact rams. The magnitude of LH-mRNA labelling was significantly greater in summer than in winter rams, and in castrated than in intact animals (P<0.001). However, the number of labelled cells was found to be the greatest in the winter (P<0.001) and was not affected by castration. FSH-mRNA expression was similar to that of LH-mRNA except that the level and extent were considerably lower. Thus, our results show an increase in the magnitude of gonadotropin subunit-mRNA in the summer and following castration; this increase appears to involve the entire pars tuberalis.     

Distribution and abundance of littoral benthic fauna in Canadian prairie saline lakes

The littoral benthos of 18 lakes in Alberta and Saskatchewan ranging in salinity from 3 to 126 (g1^–1 TDS) were investigated twice, in the spring and in the summer of 1986. Multiple Ekman dredge samples were taken at water depths of about 0.5, 1.0 and 2 metres in each transect. Two to three transects were used in each lake according to its estimated limnological diversity for a total of 114 stations. A total of 76 species was present varying from 29–31 species in the three lakes of lowest salinity (means of 3.1–5.55) to only 2 species in lakes exceeding 100. Species richness decreased rapidly in salinities greater than 15.Biomass maximum mean of 10.91 g m^–2 dry weight (maximum 63.0 g m^–2) occurred in culturally eutrophic Humboldt Lake (3.1) but one third as great in other low salinity lakes. However, biomass again increased to about 4.5 gm^–2 in two lakes of 15 As the salinity increased still further biomass declined steadily until a minimum of 0.0212 g m^–2 was recorded in most saline Aroma Lake (mean 119). Summer biomass (11 lakes) was greater than spring biomass (4 lakes) because some groups such as amphipods, corixids and ostracods became more abundant in summer. Wet weight biomass averaged 15.8 of dry weight biomass.Seasonality (spring or summer), sediment texture and organic matter content, water depth, pH, salinity (TDS) and the presence of aquatic plants ( plant cover) were considered in the matrix involving species dry weight biomass at each of 117 stations. TWINSPAN classification of the samples yielded a dendrogram with 18 indicator species. Successive dichotomies divided these indicator species into four main lake groups based on salinity, i.e., Group I: 3–10 (Gammarus, Glyptotendipes I, Chironomus cf. plumosus), Group II: 10–38%. (Hyalella, Enallagma,Bezzia), Group III: 38–63 (Hygrotus salinarius, Cricotopus ornatus), Group IV: >63 (Dolichopodidae, Ephydra hians). Each of these main groups was subdivided into smaller groups of lakes based on factors such as pH, seasonality (spring or summer species dominance), organic matter and plant cover. Depth of samples played no apparent role.     

Estimation of Standing Stock and Decomposition Rates of Labile Organic Matter in Waters of Novorossiisk Bay,Black Sea

The annual dynamics of the decomposition rate, standing stock, and residence time of labile organic matter as an index of full self-purification were investigated in Novorossiisk Bay, Black Sea. The results are suggestive of fairly effective processes of biological self-purification in polluted waters of the bay. The decomposition rate was highest (0.3–0.7 mgO₂/l per day) during the summer, and it decreased by 4–8 times in winter. The residence time of labile organic matter was 97–104 days in winter and 8–11 days in summer. Oxygen consumption rates measured in different areas of the bay conformed to their trophic status and were not above the normal level for summer.     

Fatty Acid Patterns in <Emphasis Type="Italic">Chlamydomonas</Emphasis> sp. as a Marker for Nutritional Regimes and Temperature under Extremely Acidic Conditions

Fatty acid profiles were used to characterize nutritional pathways in Chlamydomonas sp. isolated from an acidic mining lake (pH 2.7). Surprisingly, profiles of Chlamydomonas sp. grown in the lab under photoautotrophic, mixotrophic, and heterotrophic conditions at in situ deep strata lake water temperatures (8°C) were very similar, polyunsaturated fatty acids including -linolenic acid (18:33) and 16:43 along with palmitic acid (16:0) being most abundant. Therefore, heterotrophic growth of Chlamydomonas sp. at low temperatures can result in high concentrations of polyunsaturated fatty acids, as previously only described for some psychrophilic bacteria. By contrast, the cultivation of isolated Chlamydomonas sp. at 20°C, reflecting surface water temperatures, provided fatty acid patterns characteristic of the nutrition strategy applied: the concentration of polyunsaturated fatty acids decreased when the growth pathway changed from photoautotrophic via mixotrophic to heterotrophic. Total fatty acid concentration also diminished in this order. Principal component analysis confirmed the significance of FA profiling to mirror nutritional pathways. Lake-water analysis revealed low concentrations of dissolved organic carbon, mainly consisting of polymeric fulvic acids that are unable to support heterotrophic growth of Chlamydomonas sp. Polymeric fulvic acids present in the deeper strata of the lake turned out to be formed in situ on the basis of organic monomers including reduced sulfur-containing ones, as revealed by thermochemolysis and pyrolysis. Growth of Chlamydomonas sp. in the deep chlorophyll maximum is therefore assumed to mainly result from photosynthesis, despite very low photon densities. Phytol-including metabolites proved to be significant biomarkers to indicate the nutritional pathway of Chlamydomonas sp. , -Dicarboxylic acids—light-induced degradation products of unsaturated fatty acids—appeared to be good indicators of photooxidative alterations to the algal species under study.     

Seasonal succession,standing crop and determinants of primary productivity of the phytoplankton of Ministik Lake,Alberta, Canada

Ministik Lake (longitude 113°01; latitude 53°21), a well-mixed, shallow (mean depth 1.83 m), eutrophic lake is characterized by eutrophic chlorococcalean and cyanophycean phytoplankton associations, and little change in standing crop size with increasing depth. Standing crops and primary productivity are low during the winter but pronounced spring and late summer/early autumn maxima occur. Mean yearly areal standing crop (B) and primary productivity (A) were 199.2 mg m^–2 chlorophyll a and 319.5 mg C hr^–1 m^–2 respectively. Annual productivity was estimated at 1399,6 g C m^–2yr^–1. The mean increase in the extinction coefficient () per unit increase in standing crop (B) was 0.03 In units m^–1. High non-algal light attenuation (q) occurred averaging 46% which prevented the ratio B from attaining more than 74.2% of the theoretical maximum except once when selfshading occurred. Insignificant relationships existed between B (mg m^–3 chlorophyll a) and A_max (mg C hr^–1 m^–3), A and B and A and B. Close correlations existed between A and A_max/ and A and I₀ (W m^–2). The depth of the euphotic zone (Z_eu) varied between 0.6 and 2.0 m; the average relationship between z_eu and was z_eu = 3.78/_te, and the mean standing crop in the euphotic zone represented 58.3% of the theoritical maximum. The high _q values made the model of Talling (1957) inapplicable to this lake. The Q₁₀ value for the lake was 1.20. _max (mg C chlorophyll a ^–1 hr^–1) was closely related to both temperature and irradiance, and depressed by high pH values.Growth of the cyanophycean algae was correlated with temperature, chlorophycean algae with phosphate-phosphorus and temperature and the diatoms with dissolved silica and phosphate-phosphorus, but only in the case of Chaetoceros elmorii did any nutrient appear limiting. Indirect evidence that free CO₂ limited photosynthetic rates is provided by the _max:pH relationship.     

Purification and properties of recombinant β-glucosidase of the hyperthermophilic bacterium Thermotoga maritima

A -glucosidase of the hyperthermophilic bacterium Thermotoga maritima has been purified from a recombinant Escherichia coli clone expressing the corresponding gene. The enzyme was found to be a dimer with an apparent molecular mass of approximately 95 kDa as determined by size exclusion chromatography. It was composed of two apparently identical subunits of about 47 kDa (determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis). The enzyme had a bbroadsubstrate specificity and attacked -glucoside, -galactoside, -fucoside, and, to a very small extent, also -xyloside substrates. -Glycosidic bonds were not hydrolysed. Kinetic measurement of the hydrolysis of o-nitrophenyl--d-glucopyranoside (oNPGlc) and o-nitrophenyl--d-galactopyranoside (oNPGal) in the concentration ranges 0.05–20 mm and 0.1–10 mm, respectively, at 75°C resulted in non-linear Lineweaver-Burk and Eadie-Hofstee 3lots whereas cellobiose and lactose did not induce this type of effect. Lactose caused substrate inhibition above 350 mm. The enzyme was optimally active at about pH 6.1. The T. maritima -glucosidase represents the most thermostable -glucosidase described to date. In 50 mm sodium phosphate buffer, pH 6.2, at an enzyme concentration of 50 g/ml, the pure enzyme without additives retained more than 60% of its initial activity after a 6-h incubation at 95°C. Correspondence to: W. Liebl     

DNA homology and adsorption specificity of Pseudomonas aeruginosa virulent bacteriophages

Summary The DNA homology and adsorption specificity of newly isolated virulent bacteriophages of P. aeruginosa have been studied. On the basis of this analysis all phages were divided into four groups: k, m, mnP78-like and mnF82-like bacteriophages. DNA's of k as well as m phages were shown to possess different restriction patterns although they have an extensive homology. Unlike other groups, k phages were characterized by the presence of T4 DNA ligase-repaired, single-chain breaks.Abbreviations kbp kilobase pairs - EM electron microscopy     

Genetic studies with two prophages naturally resident in Serratia marcescens HY

Summary Serratia marcescens HY was cured of two native prophages, and y. Curing occurred after infection with temperate phage , but the cured strains did not become -lysogenic. One of them has been simultaneously cured of both and y. Recognition of cured colonies was based on their loss of immunity towards the respective phage. Whereas plates on the singly cured strains, it does not plate on the doubly cured strain. However, infection of it with leads to a limited phage multiplication, the average burst size being low and only part of the infected cells producing phage at all. The ability of the strain to serve as indicator for can be restored by relysogenization with either or y. In addition, some further relations between , , and y are reported in this paper.Abbreviations moi multiplicity of infection - A absorbance (optical density) - NB nutrient broth - BS buffered saline - EMB eosine methylene blue - thy thymine - leu leucine This work was supported by the Deutsche Forschungsgemeinschaft. The technical help of Miss A. Varela and Mrs. I. Steiger in some experiments is appreciated.     

Physiological relationship between the temperate phages lambda and phi80

Summary This work deals with the ability of phage 80 to provide defective mutants of with their missing functions. Functions Involved in Recombination. As shown by others, the Int mechanism of 80 cannot excise prophage . However, 80 efficiently excises recombinants from tandem dilysogens, using its Ter mechanism. Likewise, the nonspecific mechanism Red is interchangeable between 80 and . Maturation of DNA by 80. The Ter recombinants excised by 80 from tandem dilysogens are packaged into a 80 protein coat. This contrasts with the fact, already mentionned by Dove, that 80 is extremely inefficient for packaging phage superinfecting a -lysogen. The latter result is also found when the helper phage is a hybrid with the left arm of (80hy4 or 80hy41 — see Fig. 1). However, the maturation of the superinfecting is much more efficient if the 80hy used as a helper has the att-N region of (like 80hy1). Conversely a with the att-N region of 80 (hy6 — see Fig. 1) is packaged more efficiently by 80 or 80hy4 than by 80hy1. It is suggested that the maturation of chromosome superinfecting an immune cell requires a recombination with the helper phage. Vegetative Functions. Among the replicative functoons O and P, the latter only can be supplied by 80. That N mutants are efficiently helped by 80 does not tell that 80 provides the defective with an active N product; the chromosomes are simply packaged into a 80 coat. This shows that 80 is unable to switch on the late genes of . That neither 80 nor any of the 80hy tested can provide an active N product is shown in a more direct way by their complete failure to help N ^-r₁₄; this phage carries a polar mutation which makes the expression of genes O and P entirely N-dependant. The maturation of a N ^- by 80 contrasts with the fact that mutants affected in late genes (A, F or H) are not efficiently helped by 80. This suggests that the products coded by these genes are not interchangeable between 80 and , and that packaging of DNA into 80 coats is possible but inhibited when late proteins are present in the cell. Activation of the Late Genes. Among the im ₈₀ h ⁺ hybrids tested, only 80hy41 is able to switch on the late genes of a N defective mutant. This hybrid differs from the other hybrids studied here, by the fact that it has the Q-S-R region of (see Fig. 1). The results are consistant with the view that the product of Q gene is sufficient for activating the late genes of a DNA. N would thus control the expression of late genes only indirectly by controlling the expression of gene Q (Couturier & Dambly have independantly reached the same conclusion, 1970). Furthermore the failure of 80 and of the 80hy1 and 80hy4 to activate the late genes of would imply that these phages are unable to provide an Q product active on the chromosome Reciprocally, switches on the late genes of prophage 80hy41, but not of prophages 80hy1 and 80hy4. This suggests that the initiation of late genes expression takes place at a main specific site located in the Q-S-R region of the chromosome. The expression of the late genes would thus be sequential, and proceed through the left arm only when steaky ends cohere. Similar conclusions were reached independantly by Toussaint (1969) and by Herskowitz and Signer (1970).

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Ce travail a été réalisé dans le cadre du contrat d'association Euratom-U. L. B. 007-61-10 ABIB et avec l'aide du Fonds de la Recherche Fondamentale Collective.     

The phytoplankton of Lake Liddell,New South Wales: chlorophyll a concentrations,species seasonal succession,and covariation with nutrients

Samples of the phytoplankton in a freshwater lake, Lake Liddell, New South Wales (Lat: 32° 22 S, Long. 150° 1 E) were collected every 4 weeks between October 1987 and November 1988. Chlorophyll a concentrations ranged from 1.8 g 1^–1 to 9.1 g 1^–1 and were positively correlated with the following nutrient parameters: total and nett mass additions of nitrate/nitrite-N and total-N, total additions of Kjeldahl-N, and nett mass addition N-P ratios. There was no correlation between lake nutrient concentrations and chlorophyll a. Factors other than nutrient concentrations appeared to be effecting chlorophyll a concentrations as summer levels were low despite nutrient concentrations being at a maximum. In spring and summer the phytoplankton was dominated by chlorophytes, with dinoflagellates and diatoms most abundant in autumn. During winter cyanobacteria were the most abundant. The relative abundance of chlorophytes was positively correlated with in lake nitrate/nitrite-N concentrations whereas the relative abundance of cyanobacteria was negatively correlated with this parameter. Based on chlorophyll a concentrations and the phytoplankton flora Lake Liddell can be classified as mesotrophic.     

Population Dynamics of Daphnia Hyalina Leydig (Crustacea: Cladocera) in a Productive and an Unproductive Lake in the English Lake District

The population dynamics of Daphnia hyalina Leydig in a productive lake, Esthwaite Water, and an unproductive lake, Buttermere, in the English Lake District have been compared. The winter is passed as resting eggs in the bottom sediments in Buttermere and as free-swimming individuals in the planktonic zone in Esthwaite Water. In Esthwaite Water seasonal periodicity was characterised by maxima in spring and autumn and a minimum in summer; in Buttermere, there was no spring maximum and the first increase in population density was in summer. Population densities were higher and adult females were larger and laid more eggs per clutch in Esthwaite Water than in Buttermere. In each lake males became numerous in autumn. Observed rates of population increase, r and calculated birth rates, b and death rates d were nearly always higher in Esthwaite Water than in Buttermere.     

Life history,population dynamics and production of Pontoporeia hoyi (Crustacea,Amphipoda) in relation to the trophic gradient of Lake George,New York

The life history characteristics, population dynamics and production of Pontoporeia hoyi in Lake George, New York, were studied from May 1981 through October 1982. P. hoyi, in terms of both density and standing crop, is the most prevalent member of the deep water macrobenthos of Lake George. It reproduces in the winter, with young being released in the late winter-early spring. At the southernmost study site, young released in the spring grew to 6–7 mm in length and bred during their first winter. At the remaining sites, P. hoyi required two years to complete its life cycle. This difference in life history characteristics can be related to food availability and temperature differences. The open waters of the south end of Lake George are not only more productive but are also more closely associated with the littoral zone, providing a wealth of bacteria-rich detritus for benthic deposit feeders. The greater food availability in the south basin of Lake George is reflected in significantly larger brood sizes and smaller size at maturity for P. hoyi populations from the south end of the lake.The southernmost study site has significantly greater P. hoyi density and standing crop than all other sites. The cohort of the year dominated density and standing crop at the southern site while the cohort of the previous year dominated standing crop at the other sites. Peak abundance ranged from 600 · m^–2 at the north site to 2 900 · m^–2 at the south site. Cohort production ranged from 2g · m^–2 at the north site to 15g · m^–2 at the south site.     

Fine structure of early previtellogenic oocytes in Mugil (Liza) auratus Risso, 1810 (Teleostei,Mugilidae)

Summary Sequential cytological events at the onset of previtellogenesis were studied in oocytes from 12 m to 70 m in diameter of golden grey mullet. The main cytological changes observed (increase in size of cell, nucleus, nucleolus and increase in number of nucleoli, RNP particles, nuage and mitochondria) provide evidence for important synthetic processes in an early preparatory phase of oocyte development.Somatic cells (pre-follicle, follicle and thecal) are also described.     

Diversity of the mouse T cell receptor Cγ1 gene: structural analysis in C57BL/Ka

We have isolated an unusual T cell receptor chain cDNA clone (7.1) from a library made from RNA derived from adult thymus of C57BL/Ka mice. This cDNA clone corresponds to the appropriately processed C1 constant region exons preceded by 1.5 kb of J-C1 intron. The 7.1 coding region is extremely homologous to the C1 gene of BALB/c mice, differing at the protein level by a single deletion (alanine 139) and a single substitution. This latter change eliminates the sole N-linked sugar attachment site, providing a basis for strain-specific glycosylation patterns. The J-C1 intronic region contains two DNA segments (termed J1 and J2) that are highly reminiscent of joining (J) segments; both have potentially functional recombination and donor splice sequences flanking an open reading frame. Northern analysis suggests that 7.1 may be derived from a large, variable region-containing precursor.     

The carotenoids of Flavobacterium strain R1560

The main carotenoid of Flavobacterium strain R1560 has been identified as (3R,3R)-zeaxanthin. Also present were small amounts of 15-cis-phytoene, phytofluene, -carotene (7,8,7,8-tetrahydro-, -carotene plus 7,8,11,12-tetrahydro-, -carotene), neurosporene, lycopene, -zeacarotene, -carotene, -carotene, -cryptoxanthin, rubixanthin, 3-hydroxy--zeacarotene and several apo-carotenals. Zeaxanthin production was inhibited by nicotine (10 mM), and lycopene and rubixanthin accumulated. The biosynthesis of zeaxanthin is discussed in terms of pathways and also of half-molecule reaction sequences. The presence of zeaxanthin may be a characteristic of a group of Flavobacterium species, and may thus be useful in the taxonomic classification of these organisms.     

Rumen microbes and fermentation of wild sika deer on the Shiretoko peninsula of Hokkaido Island,Japan

A total of 32 wild Hokkaido sika deer (Cervus nippon yesoensis) were shot (13 in summer, nine in autumn and 10 in winter) in the Syari district, Shiretoko Peninsula of Hokkaido Island, Japan. The ingested foods, rumen fermentation parameters and microbes were determined to evaluate digestive strategy and food availability in each season. Ingested foods and ruminal characteristics greatly varied by season. Rumen digesta mainly comprised of graminoids in summer, graminoids and agricultural products in autumn, and bark and twigs in winter. Rumen pH showed seasonal differences (P<0.05) and was lowest in summer, highest in winter, and intermediate in autumn, reflecting the seasonal differences in ruminal concentration of total volatile fatty acids which were significantly lower (P<0.05) in winter than in summer and autumn. Acetate proportions were significantly higher in winter than in other seasons (P<0.05), while the opposite trend was seen in proportions of propionate and butyrate. Rumen ammonia levels showed significant seasonal differences (P<0.05), decreasing from summer to autumn to winter. Rumen protozoa levels in autumn and winter decreased to 28 and 10% of the levels observed in summer, respectively (P<0.05 for both). The rumen bacteria level in winter was lower (P<0.05) than that in autumn, but no difference was seen for the other seasonal comparisons. Gram negative cocci were present in significantly higher proportions in winter than in other seasons (P<0.05), while Gram negative curved rods were less frequently observed in winter (P<0.05). Based on these results, wild sika deer in this area are shown to survive with rumen microbial populations altered with the dietary conditions that vary greatly by season.     

Biological basis for the management of ‘lugs negra’ (Sarcothalia crispata Gigartinales,Rhodophyta) in southern Chile

The present paper describes growth dynamics in a natural bed of the resource luga negra (Sarcothalia crispata) in Guapilinao, southern Chile (41°57 S, 73°31 W). This resource is currently harvested and exported as raw material for the production of carrageenan. Seasonal variation in biomass, frond size, density and phenology was determined by periodic sampling. Natural recruitment was evaluated on different substrata added to the field; at the same time, substrata were inoculated under greenhouse conditions. Results showed that luga negra has seasonal growth: biomass increased from a minimum in spring to a maximum in mid to late summer. On the other hand, density was minimal in winter (200 ind. m^–2) and increased to 2000 ind. m^–2 in late spring. Peak abundance of mature tetrasporic fronds occurred in late summer, whereas that of cystocarpic fronds occurred in winter. Recruitment began in summer and extended into winter. Survival on different substrata were compared. Gametophytes had better survival rates on clam shells and 5 mm rope while tetrasporophytes had the best survival rate on clam shells and secondarily on boulders.     

Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata

Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb₁, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[-d-glucopyranosyl-(1,2)--d-glucopyranosyl]- 20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ene (1), 3-O-[-d-glucopyranosyl-(1,2)--d- glucopyranosyl]-20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ol (2), 3-O-[-d-gluco- pyranosyl-(1,2)--d-glucopyranosyl]-3, 12, 20(S)-trihydroxydammar-24-ene (3), and 3-O--d-glucopyranosyl-3, 12, 20(S)-trihydroxydammar-24-ene (4), identified by TOF-MS, ¹H- and ¹³C-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound.