STUDIES OF PALEOZOIC FUNGI. III. FUNGAL PARASITISM IN A PENNSYLVANIAN GYMNOSPERM

Evidence of fungal parasitism is found in the Pennsylvanian gymnospermous cone, Lasiostrobus polysacci Taylor. Indication of fungal activity is found in the outer cortical region of the axis of the cone and in the fleshy microsporophylls. Specimens exhibit severe tissue disruption, thick-walled, branched, septate hyphae, and possible reproductive structures. Parenchymatous cortical cells may also contain rounded bodies which are continuous with the cell wall. Similar structures are formed in many extant taxa in response to fungal invasion, and are termed wall appositions or callosities. Although their role in extant plants is disputed, they are clearly the product of a living host cell. Such spherical bodies, however, are not restricted to the cell periphery but in some cases occlude the cell lumen. In appearance they resemble resinous remains similar to those found in other coal ball plants. The blockage of entire cells or groups of cells may have served to retard hyphal growth or isolate infected cells. The occurrence of such structures in a Carboniferous plant provides the best evidence to date of parasitism during the Paleozoic.     

Aquatic Snails, Passive Hosts of Mycobacterium ulcerans

Accumulative indirect evidence of the epidemiology of Mycobacterium ulcerans infections causing chronic skin ulcers (i.e., Buruli ulcer disease) suggests that the development of this pathogen and its transmission to humans are related predominantly to aquatic environments. We report that snails could transitorily harbor M. ulcerans without offering favorable conditions for its growth and replication. A novel intermediate link in the transmission chain of M. ulcerans becomes likely with predator aquatic insects in addition to phytophage insects. Water bugs, such as Naucoris cimicoides, a potential vector of M. ulcerans, were shown to be infected specifically by this bacterium after feeding on snails experimentally exposed to M. ulcerans.     

Cartilage is a metazoan tissue; integrating data from nonvertebrate sources

Connective tissues are responsible for much of the variation in morphology that we see today. Cartilage is a type of connective tissue that is often considered to be restricted to vertebrates, however, cartilaginous tissues are also found within invertebrates. Unfortunately, most definitions and classification schemes for cartilages suffer from a strong vertebrate bias, severely hampering the efforts of those who have attempted to include invertebrate tissues as cartilage. To encompass all types of cartilage, current classification systems need to be expanded. Here we present vesicular cell‐rich as a new cartilage classification. Invertebrate cartilages, comparable to vertebrate cartilages at both cell and tissue levels, are composed of similar molecules, yet the extent to which they may be homologous is unknown. One option for studying the evolution of tissues is to adopt molecular phylogenetic approaches. However, the paucity of published molecular data makes addressing the evolution of cartilage using molecular phylogenetic approaches unrealistic at this time. Cartilage likely evolved from a chondroid connective tissue precursor, and may have been independently derived many times. The appearance of cartilaginous tissues of unknown phylogenetic affinities in such a wide diversity of animal groups warrants further investigation.     

MONOMORPHISM,REDUCED GENE FLOW,AND CLEISTOGAMY IN RARE AND COMMON SPECIES OF LESPEDEZA (FABACEAE)

Population genetic structure was analyzed in the rare, native prairie legume Lespedeza leptostachya Engelm. and in the widespread L. capitata Michx. Both species produce a mixture of chasmogamous and cleistogamous flowers. Allozymes were analyzed for 32 loci from 224 individuals from 12 populations of L. leptostachya and for 34 loci in 291 individuals from 12 populations of L. capitata. L. leptostachya is entirely monomorphic at all loci studied, while L. capitata shows strong among-population differentiation for the limited variation that occurs in that species. Allozyme data suggest that the level of gene flow among populations of L. capitata is very low, and that very low levels of outcrossing are effected by the chasmogamous flowers in L. capitata.     

Structure, function, and motility of vacuoles in filamentous fungi

Current information on the structure and function of motile tubular vacuoles in Pisolithus tinctorius and other fungi is reviewed. The use of fluorochromes to label the vacuole lumen is evaluated and observations on the structure and motility of vacuoles in P. tinctorius are differentiated from possible artifacts. The styryl dyes FM4-64 and MDY-64, used in yeast to demonstrate endocytosis, show little or no labeling of internal membranes in undamaged P. tinctorius cells. This agrees with our data showing that other probes for endocytosis such as Lucifer yellow CH are not taken up by hyphal tip cells. Overall, the observations do not support endocytosis in hyphal tips. It has been suggested that tubular vacuole systems carry out longitudinal transport, and evidence in favor of this hypothesis is evaluated. New data are presented to show that many of the large vacuoles in subapical cells are attached to the plasma membrane and are relatively immobile, while video sequences show movement of fluorochrome in pulses along a series of several large vacuoles, all interconnected via tubules. Tubular vacuoles from thick sections of hyphae processed under anhydrous conditions are shown by X-ray microanalysis to contain relatively high levels of P and K, as seen previously in the larger vacuoles. These results provide further evidence for a role of the tubular vacuoles in longitudinal transport of P. Copyright 1998 Academic Press.     

Neonatal vitamin K administration and childhood cancer in the north of England: retrospective case-control study.

OBJECTIVE: To explore the possible association between intramuscular vitamin K given to neonates and the subsequent development of childhood cancer. DESIGN: Retrospective case-control study on the basis of hospital records. SETTING: The former Northern Health region of England. SUBJECTS: 685 children who were born and lived in the region and who developed cancer before their 15th birthday, and 3442 controls also born between 1960 and 1991 and matched only for date and hospital of birth. The notes of a further 701 index cases were untraceable. MAIN EXPOSURE MEASURE: Administration of intramuscular vitamin K versus no exposure to vitamin K. RESULTS: There was no association between the administration of vitamin K and the development of all childhood cancers (unadjusted odds ratio 0.89; 95% confidence interval 0.69 to 1.15) or for all acute lymphoblastic leukaemia (1.20; 0.75 to 1.92), but there was a raised odds ratio for acute lymphoblastic leukaemia developing 1-6 years after birth (1.79; 1.02 to 3.15). No such association was seen in a separate cohort-based study not dependent on case note retrieval in which the rates of acute lymphoblastic leukaemia in children born in hospital units where all babies received vitamin K were compared with those born in units where less than a third received prophylaxis. CONCLUSIONS: It is not possible, on the basis of currently published evidence, to refute the suggestion that neonatal intramuscular vitamin K administration increases the risk of early childhood leukaemia. Any association may have been masked in earlier studies that did not use controls matched for time and locality by other unidentified factors affecting the spatiotemporal variations in incidence of leukaemia.     

Clupeoid Population Variability, the Environment and Satellite Imagery in Coastal Upwelling Systems

Sardine, pilchard and anchovy stocks form the basis of commercially important purse seine fisheries in eastern boundary upwelling regions. High levels of environmentally driven recruitment variability have, however, made them especially difficult to manage. Reliable forecasts of recruitment success would greatly help with the setting of catch quotas prior to each fishing season. Theories of how environmental conditions influence recruitment success, according to survival/mortality of the early life-history stages, can be divided into mechanistic and sythesis theories. Mechanistic theories are concerned with specific physical processes, whereas synthesis theories attempt to unite the various mechanistic processes within a single conceptual framework. Despite the successful testing of some theories, there has been little success in reliably predicting recruitment success from a knowledge of environmental conditions. Possible reasons include the following: non-linearity in the relationship between environmental parameters and recruitment; the poor spatial and temporal resolution of much oceanographic data; the wide range of different factors involved in determining recruitment success; and the choice of environmental index. The recent compilation of time series of satellite images for these regions offers a solution to some of these problems, and in doing so reopens the possibility of finding sufficiently good relationships between environmental conditions and recruitment success for management purposes. In particular, the high resolution of these time series allows for the construction of environmental indices across many different spatial and temporal scales. These time series also open up the possibility of quantifying the behaviour of upwelling systems according to the evolution of their spatial structure through time, using pattern analysis techniques.     

Molecular genetic analysis of the nagH gene encoding a hyaluronidase of Clostridium perfringens

A recombinant lambda phage was identified in a Clostridium perfringens genomic library by means of its ability to hydrolyse the fluorescent substrate 4-methyl-umbelliferyl--d-glucosaminide, isolated and shown to encode an endo--N-acetylglucosaminidase. This enzyme, NagH, is also known as hyaluronidase, or Mu toxin, a putative virulence factor which is likely to act on connective tissue during gas gangrene. Nucleotide sequence analysis allowed the primary structure to be deduced and showed hyaluronidase to be a large exported protein of 114392 Daltons and an enzyme of this size, endowed with the corresponding activities, was partially purified from C. perfringens. Hyaluronidase seems to be organised into two domains, an N-terminal region comprising 700 amino acids bearing the active site and a 300-residue C-terminal segment, containing three copies of an extended motif. Two other reading frames, linked to nagH, also appear to encode proteins with sugar-binding motifs.     

Sulfate control of phosphorus availability in lakes

During summer stratification large amounts of phosphorus (P) accumulate in anoxic bottom waters of many lakes due to release of P from underlying sediments. The availability to phytoplankton of this P is inversely related to the Fe:P ratio in bottom waters. Using data from 51 lakes, we tested the hypothesis that sulfate concentration in lake water may be critical in controlling the Fe:P ratio in anoxic bottom waters. Results showed that Fe:P ratios in bottom waters of lakes were significantly (p<0.001) related to surface water sulfate concentrations. The higher Fe:P ratios in low sulfate systems is due not only to higher iron concentrations in anoxic bottom waters but also to lower P concentrations in anoxic waters. Thus, our results suggest that anthropogenically induced increases in sulfate concentrations of waters (e.g. from fossil fuel burning) may have a double effect on P cycling in lakes. Higher sulfate concentrations can both increase the magnitude of P release from sediments as well as increase the availability of P released from sediments into anoxic bottom waters.     

The “interleukin 1 receptor antagonist” is a partial agonist of prostaglandin synthesis by human decidual cells

In many systems the interleukin-1 receptor antagonist opposes the effects of interleukin-1β. We considered that it might block interleukin-1β-stimulated prostaglandin production from human decidual cells. Very high levels of interleukin-1 receptor antagonist (>1000 pg/ml) had limited inhibitory effects on IL-1β-stimulated PGE2 synthesis, and lower levels of antagonist (<1000 pg/ml) increased the effects of IL-1β. Low concentrations of the antagonist alone (1–100 pg/ml) increased basal PGE2 production, whereas higher levels (10–100 ng/ml) had less effect. It seems, therefore, that in human decidua the “antagonist” is more accurately described as a partial agonist. It has been suggested that the IL-1 receptor antagonist could be used to inhibit decidual prostaglandin synthesis and thereby prevent preterm labor, but this report shows that caution should be exercised before using the receptor antagonist.