Biogeographic comparisons of marine algal polyphenolics: evidence against a latitudinal trend

Summary Marine allelochemicals generally are present in greater quantity and diversity in tropical than in temperate regions. Marine algal polyphenolics have been reported as an apparent exception to this biogeographic trend, with literature values for phenolic concentrations significantly higher in temperate than in tropical brown algae. In contrast, our results, the first reported for Caribbean brown algae (orders Dictyotales and Fucales), show that many species have high phenolic levels. In addition, both our study and previous studies with north temperate and tropical species demonstrate that there is marked variation in algal phenolic levels within species from different locations. We conclude that high phenolic concentrations occur in species from both temperate and tropical regions, indicating that latitude alone is not a reasonable predictor of plant phenolic concentrations.     

Contrasts between subsurface microbial communities and their metabolic adaptation to polycyclic aromatic hydrocarbons at a forested and an urban coal-tar disposal site

The abundance and distribution of microorganisms and their potential for mineralizing polycyclic aromatic hydrocarbons (PAHs) were measured in subsurface sediment samples at two geographically separate buried coal-tar sites. At a relatively undisturbed forested site in the northeastern United States, metabolic adaptation to the PAHs was evident: Radiolabeled naphthalene and phenanthrene were converted to ¹⁴CO₂ in core material from inside but not outside a plume of groundwater contamination. However, at the urban site in the midwestern United States these PAHs were mineralized in sediments from both contaminated and uncontaminated boreholes. Thus, clear qualitative evidence showing an adaptational response by the subsurface microbial community was not obtained at the urban site. Instead, subtler clues suggesting metabolic adaptation by subsurface microorganisms from the urban site were discerned by comparing lag periods and extents of ¹⁴CO₂ production from radiolabeled PAHs added to samples from contaminated and uncontaminated boreholes. Despite slightly higher PAH mineralization activity in contaminated borehole samples, p-hydroxybenzoate was mineralized equally in all samples from the urban site regardless of location. No striking trends in the abundances of actinomycetes, fungi, and either viable or total bacteria were encountered. However, colonies of the soil bacterium, Bacillus mycoides, were detected on enumeration plates of several samples from unsaturated and saturated zones in both urban boreholes. Furthermore, other common soil bacteria, Myxococcus xanthus and Chromobacterium violaceum, were identified in samples from the uncontaminated urban borehole. The occurrence of bacteria usually restricted to surface soil, combined with the observation of fragments of building materials in many of the core samples, suggested that past excavation and backfilling operations may have caused mixing of surface soil with subsurface materials at the urban site. We speculate that this mixing, as well as non-coal-tar-derived sources of PAHs, contributed to the PAH-mineralizing activity present in the sediment samples from the uncontaminated urban borehole.     

Microbial biomass and activity in subsurface sediments from Vejen,Denmark

Subsurface sediment samples were collected from 4 to 31 m below landsurface in glacio-fluvial sediments from the Quaternary period. The samples were described in terms of pH, electrical conductivity, chloride concentration, organic matter content, and grain size distribution. Viable counts of bacteria varied from 0.5 to 1,203 x 103 colony forming units/g dry weight (gdw); total numbers of bacteria acridine orange direct counts (AODC) varied from 1.7 to 147 × 10⁷ cells/gdw; growth rates (incorporation of [³H]-thymidine) varied from 1.4 to 60.7 × 10⁴ cells/(gdw · day); and rate constants for mineralization of ¹⁴C-labelled compounds varied from 0.2 to 2.3 × 10^–3 ml/(dpm · day) for acetate, and from 0 to 2.0 × 10^–3 ml/(dpm · day) for phenol. Sediment texture influenced the total number of bacteria and potential for mineralization; with increasing content of clay and silt and decreasing content of sand, AODC increased and the mineralization rate declined. Intrinsic permeability calculated from grain size correlated positively with mineralization rate for acetate. Statistical correlation analysis showed high correlations between some of the abiotic parameters, but it was not possible to point out a single abiotic parameter that could explain the variation of size and activity of the microbial population. The microbial data obtained in these geologically young sediments were compared to literature data from older sediments, and this comparison showed that age and type of geological formation might be important for the size and activity of the microbial populations.Offprint requests to: H.-J. Albrechtsen.     

INCREASE IN SIZE AND CELL NUMBER OF LATERAL ROOT PRIMORDIA IN THE PRIMARY OF INTACT PLANTS AND IN EXCISED ROOTS OF PISUM SATIVUM AND VICIA FABA

Increase in cell number, and in anlage volume and length have been investigated during the development of lateral root primordia in roots of intact plants of Pisum sativum and Vicia faba and in excised roots of both species cultured in White's medium supplemented with 2% sucrose. With the exception of primordia in excised roots of Vicia, the general equation which best described increase in each aspect of primoridium growth measured against time was that for exponential growth. When the times necessary for cell number and primordium volume and length to double were determined at intervals over the period of development studied, however, they were found to vary. Similarly, estimates of the size of the proliferative fraction of cells at different times during anlage development indicated that this index of meristematic activity also fluctuated over the developmental period investigated, i.e., increase in cell number and in primordium volume and length do not occur in a truly exponential fashion as the primordia increase in size and cell number. One difference between anlage development in the roots of intact plants and in those grown in culture was that whereas the former primordia completed their development and emerged as lateral roots over the period of the investigation, the latter did not. Moreover, cell doubling time and anlage volume and length doubling times were longer, and the proliferation fraction of cells lower, over the whole period of, and at intervals during, primordium development in the excised roots compared with the results obtained for the roots of the corresponding intact plants.     

Increased Noradrenergic Metabolism in the Cerebellum of the Mouse Mutant Dystonia Musculorum

Abstract: The neurological mouse mutant dystonia musculorum exhibits bizarre appendicular and truncal dystonia without known cerebellar histopathology. We evaluated striatal dopamine and cerebellar norepinephrine metabolism in this mutant and compared the results with those obtained in wild-type BALB/c and B6C3 controls. Tyrosine hydroxylase activity and dopamine metabolite levels (homovanillic acid and 3,4-dihydroxyphenylacetic acid) in the striatum of the mutant were similar to controls. Tyrosine hydroxylase activity and the steady-state level of 3-methoxy-4-hydroxyphenethyleneglycol, a metabolite of norepinephrine, in the cerebellum were 38% and 42-66%, respectively, greater in the mutant. However, the level of norepinephrine was similar (∼350 ng/g). Further, a Purkinje cell-specific marker, cGMP-dependent protein kinase, was unchanged in the mutant and no Purkinje cell pathology was observed with light microscopy. The lack of Purkinje cell derangement and similar levels of cerebellar norepinephrine and cGMP-dependent protein kinase activity suggest that increased norepinephrine metabolism in the cerebellum of this mutant is not a morphological response to gross target cell loss during morphogenesis. The observed changes may be a reaction to abnormal impulse traffic or altered input/output pathways to the mutant cerebellum during its development.     

Analysis of development and growth in a mutant of Physarum polycephalum with defective cytokinesis

Cultures of amoebae of the mutant strain ATS23 isolated from strain CLd of Physarum polycephalum contain multinucleate cells and cells with increased nuclear DNA content. Plasmodia derived from ATS23 clones show abnormal morphology and defective sporulation. All abnormalities are enhanced by high incubation temperature (31 °C). Genetic analysis suggested that all the abnormalities were caused by a single mutation, denoted hts-23. The kinetics of plasmodium formation were followed in cultures of apogamic amoebae carrying hts-23 and hts⁺ (wild type) respectively. Results indicated that, relative to wild type, hts-23 did not increase the rate of plasmodium formation. There was evidence that, in both mutant and wild-type strains, commitment to plasmodium development occurred in uninucleate cells. Analysis of cell pedigrees by time-lapse cinematography indicated that the primary abnormal event in cultures of hts-23 amoebae was failure of cytokinesis; an apparently complete cleavage furrow was formed but cell separation failed, resulting in a binucleate cell. This event occurred randomly in pedigrees in which the majority of divisions were completed normally; its frequency increased during incubation at 31 °C. All other abnormalities in hts-23 amoebal cultures could be attributed to this primary event, assuming that DNA synthesis continued in the absence of cytokinesis and that the binucleate cells underwent the amoebal type of “open” mitosis, allowing the possibility of spindle fusion. This implies that the acquisition of “closed” mitosis is an essential early step in plasmodium development.