Altered sexual maturation and gamete production in wild roach (Rutilus rutilus) living in rivers that receive treated sewage effluents.

Disruption in gonadal development of wild roach living in U.K. rivers receiving large volumes of treated sewage effluent is manifest in a variety of ways, ranging from malformation of the germ cells and/or reproductive ducts to altered gamete production. Intersex fish were also found to have an altered endocrine status and an elevated concentration of plasma vitellogenin. Gonadal growth was inhibited only in severely intersex fish, whereas progression of spermatogenesis was delayed in a large proportion of all intersex and exposed male fish. In contrast to the effects observed in the intersex and exposed male fish, the maturation of ovaries in female fish inhabiting effluent-contaminated rivers appeared to be less obviously affected, although a higher incidence of oocyte atresia was found in the effluent-exposed fish compared with the reference fish. A positive correlation was found between the proportion of female tissue in the gonads of intersex fish and their plasma vitellogenin concentration, suggesting that vitellogenin can be an indicator for the level of gonadal disruption in intersex roach. The estradiol-17beta concentration in intersex fish was intermediate between the concentration found in males and females, and the plasma testosterone was between 2- and 3-fold higher in intersex fish compared with male fish. These data suggest a link between altered endocrine status in intersex and female fish and gonadal disruption. Spermiation was also affected in roach living in effluent-impacted rivers: a lower proportion of fish were found releasing sperm, and in those intersex fish that were spermiating, a reduced milt volume and a reduced sperm density were found. All intersex fish had malformations of the reproductive duct(s), and in severely affected fish, the ducts were occluded, thus preventing release of gametes. In view of the widespread occurrence of intersexuality in wild fish populations in rivers throughout the United Kingdom, assessment of the reproductive capabilities of these intersex roach is clearly needed to understand the impact of this phenomenon on roach fertility.     

Biodiversity of the Bacterial Flora on the Surface of a Smear Cheese

The bacteria on the surface of a farmhouse smear-ripened cheese at four stages of ripening (4, 16, 23, and 37 days) from inoculated (i.e., deliberately inoculated with Brevibacterium linens BL2) and noninoculated (not deliberately inoculated with B. linens BL2) cheese were investigated. The results show that, contrary to accepted belief, B. linens is not a significant member of the surface flora of smear cheese and no microbial succession of species occurred during the ripening of the cheeses. Of 400 isolates made, 390 were lactate-utilizing coryneforms and 10 were coagulase-negative Staphylococcus spp. A detailed analysis of the coryneforms was undertaken using phenotypic analysis, molecular fingerprinting, chemotaxonomic techniques, and 16S rRNA gene sequencing. DNA banding profiles (ramdom amplified polymorphic DNA [RAPD]-PCR) of all the coryneform isolates showed large numbers of clusters. However, pulsed-field gel electrophoresis (PFGE) of the isolates from the cheeses showed that all isolates within a cluster and in many contiguous clusters were the same. The inoculated and noninoculated cheeses were dominated by single clones of novel species of Corynebacterium casei (50.2% of isolates), Corynebacterium mooreparkense (26% of isolates), and Microbacterium gubbeenense (12.8% of isolates). In addition, five of the isolates from the inoculated cheese were Corynebacterium flavescens. Thirty-seven strains were not identified but many had similar PFGE patterns, indicating that they were the same species. C. mooreparkense and C. casei grew at pH values below 4.9 in the presence of 8% NaCl, while M. gubbeenense did not grow below pH 5.8 in the presence of 5 to 10% NaCl. B. linens BL2 was not recovered from the inoculated cheese because it was inhibited by all the Staphylococcus isolates and many of the coryneforms. It was concluded that within a particular batch of cheese there was significant bacterial diversity in the microflora on the surface.     

The latitudinal position of peak marine diversity in living and fossil biotas

Aim Peak marine taxonomic diversity has only rarely occurred at or near the equator during the Phanerozoic Eon, in contrast to the present‐day pattern. This fundamental difference is difficult to reconcile because the latitude at which peak diversity occurs for living marine taxa has not yet been explicitly determined at a broad taxonomic and spatial scale. Here, we attempt to determine this value in order to compare the contemporary and fossil patterns directly. Location Our data are global in coverage. Methods We used a literature compilation of 149 present‐day marine latitudinal diversity gradients. We summed the number of marine taxa that exhibited peak diversity within 10° latitudinal bins. In addition, we recorded locality data, general habitat (benthic/pelagic), and the taxonomic level of the study organisms. Results We found that peak diversity for most sampled marine taxa currently occurs between 10° and 20° N, even after correcting for a Northern Hemisphere sampling bias. Moreover, this peak position is a global phenomenon: it is found across habitats and higher taxa, within all sampled ocean basins, and on both sides of the Atlantic and Pacific oceans. Benthic taxa, which dominate our data, exhibit one peak at 10°–20° N, while pelagic taxa exhibit a peak at 10°–20° N and an additional peak at 10°–20° S, producing a distinct trough at the equator. Main conclusions Our data indicate that peak marine diversity for many taxa is currently within 10°–20° N rather than at the equator, and that this is not likely to result from either undersampling at lower latitudes or the pattern being dominated by a particular taxon. Possible explanations may include a coincidence with the intertropical convergence zone, a mid‐domain effect, abundant shallow marine habitat, or high ocean temperatures at latitudes nearest the equator. Regardless of its exact cause, the position of peak diversity should be considered a fundamental feature of the latitudinal diversity gradient that must be accounted for within attempts to explain the latter’s existence.     

Generic relationship between calcium intake and radiostrontium transfer to the milk of dairy ruminants

The hypothesis is tested that there is a generic relationship between the calcium intake and the transfer of radiostrontium to milk which can be used for all dairy ruminants. In addition to the daily calcium intake, the relationship also requires values for the strontium to calcium observed ratio, which describes the discrimination in transfer of the two elements to milk (a value of 0.11 is used), and the calcium concentration in milk. The relationship had previously only been validated for dairy cattle as there were insufficient data for other ruminant species. Here, we present recently available data for dairy goats, and also a limited amount of data for sheep derived from the literature. From the comparison between these data and predicted values, we conclude that it is possible to derive a generic model of the transfer of radiostrontium to the milk of dairy ruminants. Received: 12 December 1997 / Accepted in revised form: 23 March 1998     

Widespread hybridization within mound‐building wood ants in Southern Finland results in cytonuclear mismatches and potential for sex‐specific hybrid breakdown

Hybridization and gene flow between diverging lineages are increasingly recognized as common evolutionary processes, and their consequences can vary from hybrid breakdown to adaptive introgression. We have previously found a population of wood ant hybrids between Formica aquilonia and F. polyctena that shows antagonistic effects of hybridization: females with introgressed alleles show hybrid vigour, whereas males with the same alleles show hybrid breakdown. Here, we investigate whether hybridization is a general phenomenon in this species pair and analyse 647 worker samples from 16 localities in Finland using microsatellite markers and a 1200‐bp mitochondrial sequence. Our results show that 27 sampled nests contained parental‐like gene pools (six putative F. polyctena and 21 putative F. aquilonia) and all remaining nests (69), from nine localities, contained hybrids of varying degrees. Patterns of genetic variation suggest these hybrids arise from several hybridization events or, instead, have backcrossed to the parental gene pools to varying extents. In contrast to expectations, the mitochondrial haplotypes of the parental species were not randomly distributed among the hybrids. Instead, nests that were closer to parental‐like F. aquilonia for nuclear markers preferentially had F. polyctena's mitochondria and vice versa. This systematic pattern suggests there may be underlying selection favouring cytonuclear mismatch and hybridization. We also found a new hybrid locality with strong genetic differences between the sexes similar to those predicted under antagonistic selection on male and female hybrids. Further studies are needed to determine the selective forces that act on male and female genomes in these newly discovered hybrids.     

Starch as a sugar reservoir for nematode-induced syncytia

The plant parasitic nematode Heterodera schachtii invades the roots of Arabidopsis thaliana to induce nematode feeding structures in the central cylinder. During nematode development, the parasites feed exclusively from these structures. Thus, high sugar import and specific sugar processing of the affected plant cells is crucial for nematode development. In the present work, we found starch accumulation in nematode feeding structures and therefore studied the expression genes involved in the starch metabolic pathway. The importance of starch synthesis was further shown using the Atss1 mutant line. As it is rather surprising to find starch accumulation in cells characterised by a high nutrient loss, we speculate that starch serves as long- and short-term carbohydrate storage to compensate the staggering feeding behaviour of the parasites.Key words: Heterodera schachtii, Arabidopsis, nematode, starch metabolism, syncytiaThe obligate plant parasitic nematode Heterodera schachtii is entirely dependent on a system of nutrient supply provided by the plant. Host plants—among those the model plant Arabidopsis thaliana—have to endure invasion of second stage juveniles and the establishment of nematode feeding structures in the plant''s vascular cylinder. For induction of the specific feeding structures, the juveniles pierce one single plant cell with their stylet and inject secretions, thus triggering the formation of a syncytium by local cell walls dissolutions.¹ Further, the central vacuole of the syncytial cells disintegrates, nuclei enlarge and many organelles proliferate.¹ About 24 hours after feeding site induction, the nematode juveniles start feeding in repetitive cycles.² Syncytia have previously been described as strong sinks in the plant''s transport system.³ Thus, in the recent years several studies were carried out to discover solute supply to syncytial cells.^4–7 To our present knowledge, syncytia are symplasmically isolated in the first days of nematode development. During that period, the nematodes depend on transport protein activity in the syncytia plasmamembranes. At later stages plasmodesmata appear to open to the phloem elements, facilitating symplasmic transport.Incoming solutes may either be taken up by the feeding nematode or are synthesised and catalysed by the syncytium''s metabolism. Due to the microscopically observable high density of the cytosol¹ and the increased osmotic pressure,⁸ syncytia appear to accumulate high solute concentrations. In fact, significantly increased sucrose levels have been found in syncytia in comparison to non-infected control roots.⁷ In case of high sugar levels, plant cells generally synthesize starch in order to reduce emerging osmotic stress.⁹ The aim of the work of Hofmann et al.,¹⁰ was to elucidate if starch is utilised as carbohydrate storage in nematode-induced syncytia and to study expression of genes involved in starch metabolism with an emphasis on nematode development.Starch levels of nematode induced syncytia and roots of non-infected plants grown on sand/soil culture were measured by high performance liquid chromatography (HPLC). The results showed a high accumulation of starch in syncytia that was steadily decreasing during nematode development. The accumulation of starch could further be localised within syncytial cells by electron microscopy. Based on these results, we studied the gene expression of the starch metabolic pathway by Affymetrix gene chip analysis. About half of the 56 involved genes were significantly upregulated in syncytia compared to the control and only two genes were significantly downregulated. Thus, the high induction of the gene expression is consistent with the high starch accumulation. Finally, we applied an Arabidopsis mutant line lacking starch synthase I expression that has been described previously.¹¹ Starch synthase I was the second highest upregulated gene in syncytia. It catalyses the linkage of ADP-glucose to the non-reducing end of an a-glucan, forming the linear glucose chains of amylopectin. In a nematode infection assay we were able to prove the significant importance of the gene for nematode development.With the presented results, we can unambiguously prove the accumulation of starch and the induction of the gene expression of the starch metabolic pathway in nematode-induced syncytia. The primary question however is: why do syncytia accumulate soluble sugars and starch although their metabolism is highly induced and nematodes withdraw solutes during continuously repeating feeding cycles?One explanation may be found where least expected—in nematode feeding. It is the feeding activity that induced solute import mechanisms into syncytia resulting in a newly formed sink tissue. However, during moulting events to the third, the fourth juvenile stage and to the adult stage nematodes interrupt feeding for about 20 hours.² During this period sugar supply mechanisms will most probably not be altered thus leading to increasing levels of sugars in the syncytium. Starch may serve as short-term carbohydrate buffering sugar excess. Further, starch may serve as long-term carbohydrate storage during nematode development. In the early stages of juvenile development nematodes withdraw considerably small quantities (about 0,8-times the syncytium volume a day).¹² At later stages, nutrient demand increases so that adult fertilised females require 4-times the syncytium volume per day in order to accomplish egg production.¹² Thus, excessive sugar supply in the first days may be accumulated as starch that gets degraded at later stages when more energy is required from the parasites. Consequently, starch reserve serves as both short-term and long-term carbohydrate storage in nematode-induced syncytia in order to buffer changing feeding pattern of the parasites.? Open in a separate windowFigure 1Arabidopsis wild-type Columbia-0 plants were grown in sand/soil culture. Nematode-induced syncytia and non-infected control roots were harvested at 10, 15 and 20 days after inoculation (dai) and starch content was measured as glucose (Glc) equivalents. Values are means ± SE, n = 3. Different letters indicate significant variations (p < 0.05). © ASPBOpen in a separate windowFigure 2Transmission electron microscope picture of a cross-section of a syncytium associated with female fourth stage juvenile (H. schachtii) induced in roots of Arabidopsis. Bar = 2 µm. S, syncytium; Se, sieve tube; arrow, plastid; asterisk, starch granule. © ASPB     

Immunoglobulin G galactosylation and sialylation are associated with pregnancy-induced improvement of rheumatoid arthritis and the postpartum flare: results from a large prospective cohort study

Introduction  

Improvement of rheumatoid arthritis (RA) during pregnancy has been causatively associated with increased galactosylation of immunoglobulin G (IgG) N-glycans. Since previous studies were small, did not include the postpartum flare and did not study sialylation, these issues were addressed in the present study.     

Phytoestrogens as natural prodrugs in cancer prevention: dietary flavonoids

There are many reasons why vegetables and fruits may protect against cancer. As well as containing vitamins and minerals, which help keep the body healthy and strengthen the immune system, they are also good sources of biologically active compounds, which can help to protect cells in the body from damage that can lead to cancer. Notably, dietary flavonoids and other polyphenols are thought to have an important role as chemopreventive agents. Most studies on the possible mechanism of the chemopreventive action of dietary compounds have assumed that free hydroxyl groups of flavonoids and other polyphenols are necessary for their biological effects. However, in the human body dietary polyphenols are rapidly conjugated by glucuronosyltransferases and sulfotransferases, two enzymes that are abundantly present in the small intestine and liver, through which all of the oral dose must pass. Thus, most polyphenols that have been studied, e.g. quercetin, kaempferol, diosmetin, and resveratrol, would not be expected to reach internal organs beyond sites directly along the gastrointestinal tract. When the hydroxyl groups in polyphenols are methylated, the resulting compounds are much less prone to glucuronidation and sulfation. Thus methoxylated compounds are more metabolically stable, increasing their bioavailablity. The peel of various Citrus species can contain high concentrations of polymethoxyflavones, whereas the juice mainly contains hydroxylated flavones. At present, very little is known about the mechanisms by which methoxylated flavones may affect growth and development of tumour cells. Recently, it was shown that tumour specific enzymes can catalyze the O-demethylation of methoxylated flavones, resulting in the formation of flavones with free hydroxyl groups. We propose that demethylation of methoxylated flavones is another example of bioactivation of naturally occurring prodrugs.