Sex-biased dispersal promotes adaptive parental effects

Background  

In heterogeneous environments, sex-biased dispersal could lead to environmental adaptive parental effects, with offspring selected to perform in the same way as the parent dispersing least, because this parent is more likely to be locally adapted. We investigate this hypothesis by simulating varying levels of sex-biased dispersal in a patchy environment. The relative advantage of a strategy involving pure maternal (or paternal) inheritance is then compared with a strategy involving classical biparental inheritance in plants and in animals.     

Antitumour activities of levans produced by Zymomonas mobilis strains

Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.     

Substrate particle size affects pit building decision and pit size in the antlion larvae Euroleon nostras (Neuroptera: Myrmeleontidae)

Abstract. The larvae of the antlion Euroleon nostras are pit-builders, constructing pitfall traps in loose sand. The number of pits and the pit diameter are recorded when larvae are kept in substrates with different particle sizes. The most convenient pit-building sand fractions are two fractions with fine sand (≤ 0.23 mm; 0.23–0.54 mm). The largest pits are constructed in sand with a particle size of 0.23–0.54 mm. In this sand fraction, larvae of all three instars most readily build pits. No pits are constructed in sand with a particle size greater than 1.54 mm. First- and second-instar larvae avoid building pits in substrates of particle size 1–1.54 mm, but third-instar larvae construct pits in this sand fraction. It is assumed that the antlion is capable of distinguishing between substrate types and this hypothesis is tested by giving larvae the choice of building a pit in one of four particle-size fractions. Larvae of all three instars prefer to build pits in the fraction with a particle size of 0.23–0.54 mm. Only third-instar larvae build pits in all four fractions, but only occasionally in the coarser fraction.     

Inhibition of N-linked oligosaccharide processing does not prevent the secretion of thyroglobulin. A study with swainsonine and deoxynojirimycin

The effects of two drugs, swainsonine (SW) and deoxynojirimycin (dNM), on synthesis and export of thyroglobulin were studied in folliculized porcine thyroid cells cultured in a serum-free medium. These drugs were expected to alter N-linked glycans in thyroglobulin. Newly synthesized thyroglobulin labeled with [2-3H]mannose or [4,5-3H]leucine was obtained by immunoprecipitation from the follicular contents, culture media and cell extracts; the first two compartments, containing secreted thyroglobulin, were sometimes analyzed together. Leucine incorporation was not inhibited by SW and only slightly by dNM. In contrast dNM strongly decreased mannose incorporation (by up to 50-75% at 1-3 mM). However after 16-h mannose labelings, SW and/or dNM at 2.5 microM and 3 mM respectively did not significantly modify the relative proportions of radioactive thyroglobulin in the above-mentioned compartments. Pronase glycopeptides prepared from these thyroglobulins were examined with respect to behaviour on concanavalin-A-Sepharose and position on Bio-Gel P-4. Oligosaccharides released by endoglucosaminidase H and with high affinity for the lectin, i.e. high-mannose and certain hybrids, were further characterized by various exoglycosidase treatments. Thyroglobulin from control cells displayed complex and high-mannose glycans comparable in size and proportion to those attributed to tissue-extracted porcine thyroglobulin. After treatment with SW (an inhibitor of alpha-mannosidase II), complex glycans were almost totally replaced by sialylated hybrid glycans. In contrast to this nearly total suppression, dNM (an inhibitor of the trimming glucosidases) caused only a 30% decrease in labeling of complex units and an about 50% increase in high-mannose glycans, covered to some degree by glucose. Finally a [3H]leucine pulse-chase study was performed on thyroglobulin secretion in the absence or presence of both SW and dNM. Though a slowdown was detectable in the first few hours, this study revealed no change in the long-term export of thyroglobulin.     

Study of elastase-type activity in blister fluids of recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is characterized clinically by blister formation due to minor trauma and ultrastructurally by a progressive disappearance of anchoring fibrils at the dermoepidermal junction and of the oxytalan-type fibers which belong to the elastic fiber system. In this study, we determined the elastase-type activity in blister fluid obtained from 8 patients suffering from RDEB as compared to the suction fluid of experimental blisters in a healthy person and to the blister fluid of a patient suffering from epidermolysis bullosa simplex. One patient with dominant dystrophic epidermolysis of the albopapuloid type was also studied. Seven of the eight children with RDEB showed highly elevated values. The eighth child, treated with etretinate, as well as the patient suffering from dominant epidermolysis bullosa had moderately increased values. The determination of elastase-type activity in the blister fluid could therefore be useful to establish the differential diagnosis of recessive dystrophic epidermolysis bullosa.     

Soft rot Erwinia bacteria in surface and underground waters in southern Scotland and in Colorado, United States

An anaerobic liquid enrichment method followed by plating on a selective medium revealed that the soft rot coliform bacterium Erwinia carotovora subsp. carotovora was generally present in water from drains, ditches, streams, rivers and lakes (including reservoirs) in southern Scotland and in Colorado, United States, in mountainous, upland and arable areas through the year. Many sites were remote from susceptible or diseased crops. Erwinia carotovora subsp. atroseptica was isolated much less frequently and no Erwinia bacteria were isolated from underground waters. Erwinia bacteria were also found in rain-water in Scotland, in winter snow from mountain passes in Colorado, and in sea water from the west and east coasts of Scotland and from the coasts of Oregon, California, Texas, Louisiana and Florida. The significance of the occurrence of these bacteria in water is discussed in relation to the control of blackleg and soft rot diseases of potato by production of Erwinia -free stocks.     

Isolation and sequence analysis of the genomic DNA fragment encoding an aspartic proteinase inhibitor homologue from potato (Solanum tuberosum L.)

A genomic DNA clone encoding an aspartic proteinase inhibitor of potato was isolated from a lambda EMBL3 phage library using the aspartic proteinase inhibitor cDNA as a hybridization probe. The gene has all characteristic sequences normally found in eucaryotic genes. Typical CAAT and TATA box sequences were found in the 5-upstream region. In this part are also two putative regulatory AGGA box sequences located. In the genomic sequence there are no intron sequences interrupting the coding region. An open reading frame of the gene encodes a precursor protein of 217 amino acids which shows high percent identity with the aspartic proteinase inhibitor cDNA.     

Benthic-pelagic flux rates on mussel beds: tunnel and tidal flume methodology compared

Material flux rates in an intertidal mussel bed were measured synchronously over two tidal cycles in June 1989 with Benthic Ecosystem Tunnels and a double lane flume. The tunnels enclosed the near bottom water, whereas the flume canalized the total water column. One tunnel was set up in a mussel bed and another one in an adjacent sand bottom as a control. The flume enclosed a mussel lane and a sand lane. In the tunnel and in the flume the mussel bed revealed ammonium and phosphate discharge. At the same time, phytoplankton, dominated byPhyaeocystis globosa, was taken up intensively. These flux rates showed the same tendency but they were higher in the flume than in the tunnel. Different tendencies and flux rates for oxygen and particulate organic matter (POC, PN) were found in flume and tunnel. These differences demonstrate the importance of water column processes regarding the material exchange of a mussel bed. Tunnels enclose smaller bodies of water and are therefore expected to detect even small effects of the benthos on the passing water. In flumes, benthic influence may be diluted over the entire water column but conditions are more natural. The use of flumes is restricted to shallow waters while tunnels have the potential to be used at any depth.     

Structural variability of collagen fibers in the calcareous axial rod of a sea pen

Previous studies revealed that the organic matrix of the skeletal rod of the sea pen, Veretillum cynomorium, contained about 50% collagenous protein. The present ultrastructural study, based upon conventional staining methods, shows the existence of an abundant, longitudinally arranged nonbanded and fibrillar material separated by a reticular matrix. After incubation with ³H-proline, labeling is specifically localized on the fibrillar material. Some fibers occasionally display a transverse striation with a period of 11 to 14 nm which can be associated with a chevron striation. Infrequently, some other fibers display a more distinct banding of 55 to 70 nm or even yield a checkerboard pattern. However, a majority of fibers remain without a regular structure comparable to the periodic striations observed in the collagen of other animals. After treatment with 1% PTA in 70% ethanol, all the fibers show a clear banding of 14 nm and some of them possess two types of striations. The same result is obtained on fibers mechanically dissociated and negatively stained. As these methods show a periodic banding pattern on all the fibers, it is likely that all the fibers (striated or not) observed after routine electron microscopy correspond to collagen material. This collagen appears to be both polymorphic and completely new in comparison to that which is characteristic of the mesoglea. The polymorphic aspect is compared to that obtained from vertebrate collagens.     

Die vertikale Verbreitung der Lituolaceen und Miliolaceen (Foraminifera) an einem Unterwasserkliff in der Adria (Jugoslawien)

The distributional patterns of recent benthic foraminifera have been studied in the Adriatic Sea near the Kornati Islands Middle Dalmatia at a submarine cliff of 70 m height. One of the submarine cliffs is exposed to the open sea, the other one to the channel. Diagrams show the composition of the foraminiferal fauna with respect to the highest systematic categories to the species level, as well as the distribution and abundance of the most common foraminifera of the superfamilies Lituolacea and Miliolacea. These diagrams can be used for bathymetric interpretations and for the definition of ecological niches. Nearly half of the species are known also from Ancient environments.