Population genetic structure,parasite infection and somatic condition of pumpkinseed Lepomis gibbosus (Actinopterygii: Centrarchidae) in the Oder river basin

In Poland, distribution of non-native pumpkinseed Lepomis gibbosus (Centrarchidae) is strictly limited to the Oder river basin, where it was introduced in the early 20th century. Recently, several populations have been found in waterbodies adjacent to the Oder, particularly in its lower reaches. In this study, we compare the genetic relatedness of populations in the Oder basin with other European populations using nuclear (microsatellite) and mitochondrial (partial cytochrome c oxidase subunit I; cox1) markers. Microsatellite analysis indicated that four populations in the lower Oder form a separate cluster, while one in the middle Oder clustered with Danubian populations, from where probably having been introduced. Microsatellite data suggested that the lower Oder populations differ from other non-native European populations, making it impossible to estimate the source of introduction. Nevertheless, analysis of cox1 indicated that Oder pumpkinseeds belong to the same haplotype as the vast majority of European populations. Parasitological examination confirmed the presence of two North American species, the monogenean Onchocleidus dispar and trematode Posthodiplostomum centrarchi, in the lower Oder, both previously unknown in the region. Fifteen other parasite species were acquired, including glochidia of invasive Sinanodonta woodiana. In the middle Oder, parasite infection was more limited. Fish from the Gryfino Canal, considered one of the most invasive populations in Europe, showed the highest parasite abundance and diversity, and the highest somatic condition and growth rate due to warm water released from the Dolna Odra power plant. Our results highlight significant differences in somatic condition and parasite infection in long-established non-native pumpkinseed populations in the same river system, reflecting mainly environmental conditions.     

The effect of a liquid elemental diet on cell proliferation in the colon of rats

Summary A liquid elemental diet (Vivonex) was given to rats for 6 days while control animals received a normal diet. At the end of the experiment each animal received one intraperitoneal injection of tritiated thvmidine at 8a.m. Animals from each group were killed hourly during the first 24h after the injection and the proliferative activity was studied by autoradiography of the mucosa of the colon using the labeled mitoses-wave method.The epithelial cell proliferation was significantly decreased in the colon of the Vivonex-fed animals.     

Isolation and identification of some guanidino compounds in the urine of patients with hyperargininaemia by liquid chromatography,thin-layer chromatography and gas chromatography-mass spectrometry

Liquid column chromatographic studies of monosubstituted guanidino compounds, which are excreted in the urine of patients with hyperargininaemia are reported. The guanidino-positive peaks, with the highest excretion values, were isolated from urine and the isolated compounds were identified by thin-layer chromatography and gas chromatography—mass spectrometry. Guanidinoacetic acid, N-α-acetylarginine, argininic acid, γ-guanidinobutyric acid, arginine and α-keto-δ-guanidinovaleric acid were found to be excreted at high levels in the urine of patients with hyperargininaemia compared with controls.     

Urinary prostaglandin and kallikrein excretion are not flow dependent in the rat

To study the relationship between urine flow, urinary prostaglandin (PG) and kallikrein excretion in the rat high urine flow was induced in hydropenic Long-Evans rats by either hypotonic volume expansion or with manniitol or with furosemide. PGE, excretion remained unchanged during hypotonic volume expansion (134.5 ± 29.7 before and 153.0 ± 48.9 pg/min after) while it decreased significantly with mannitol (from 166.3 ± 32.4 to 45.2 ± 8.2 pg/min, p<0.01) and with furosemide (from 170.0 ± 20.4 to 29.5 ± 5.3 pg/min, p<0.001). PGF_2α excretion rates were slightly reduced following all three interventions. Urinary kallikrein excretion remained unchanged in all three groups of animals. It is concluded that, in contrast to human and dogs in the rat urine flow and urinary PG excretion are not interlinked.     

Membrane-mediated assembly of the prothrombinase complex

Prothrombinase assembly was studied on macroscopic planar bilayers consisting of 20% dioleoyl-phosphatidylserine (DOPS) and 80% dioleoyl-phosphatidylcholine (DOPC). The dissociation constant for the binding of factor Xa to the bilayer, measured by ellipsometry, was Kd = 47 +/- 8 nM (mean +/- S.D.) and this value was lowered to Kd = 2.2 +/- 0.3 pM by preadsorption of factor Va. This latter value was determined from direct measurement of steady-state thrombin production. A comparable value of Kd = 1.0 +/- 0.1 pM was found by repeating these experiments in suspensions of phospholipid vesicles, and it was verified that prothrombinase assembly was not influenced by the addition of prothrombin. Using a minute amount (0.094 fmol cm-2) of preadsorbed factor Va, it was found that the rate of prothrombinase assembly exceeds the rate of collisions between Xa molecules from the buffer and the sparse Va molecules on the bilayer. Apparently, factor Xa adsorbs first to the membrane and then associates rapidly with factor Va by lateral diffusion. The data indicate almost instantaneous equilibrium of this complex formation on the surface with a lower limit for the bimolecular rate constant of kon = 2.8 x 10(13) (mol/cm2)-1 s-1. In suspensions of small phospholipid vesicles, prothrombinase assembly is collisionally limited and the value of kon should be proportional to vesicle diameter. This was verified with a method for estimation of kon values from thrombin generation curves. Values of 0.36 x 10(9) and 1.6 x 10(9) M-1 s-1 were found for vesicles of 20-30- and 60-80-nm diameter, respectively.     

Nucleotide sequence of the bovine cyclic-AMP responsive DNA binding protein (CREB2) cDNA

The bovine cyclic AMP responsive binding protein cDNA (CREB2) was isolated from a lambda-gt11 cDNA expression library using a 32P labelled oligonucleotide corresponding to the 21 bp enhancer sequence present in the BLV LTR. The deduced amino acid sequence revealed that CREB2 contains a leucine zipper structure (residue 295 to 316), a basic amino acid domain (residue 268 to 291) and several potential phosphorylation sites.     

Clustering of lipid-bound annexin V may explain its anticoagulant effect.

In 1985 we isolated a new vascular anticoagulant protein VAC alpha, now called annexin V, with a high binding affinity (Kd less than 10(-10) M) for phospholipids. Its anticoagulant effect was attributed to displacement of coagulation factors from the phospholipid membrane. The present study demonstrates that the inhibition of prothrombinase activity by annexin V strongly depends on the curvature of the membrane surface and on the calcium concentration. Half-maximal inhibition of prothrombinase on and binding of annexin V to small vesicles, composed of 20% phosphatidylserine and 80% phosphatidylcholine, requires 2-3 mM calcium. With large vesicles and planar bilayers considerably less calcium is required for inhibition of prothrombinase and for lipid binding. Half-maximal binding of annexin V to large vesicles and to planar bilayers occurs at 0.7 and 0.2 mM calcium, respectively. This seemingly confirms the displacement model. The displacement of coagulation factors, however, proved to be incomplete, with residual surface concentrations of factors Xa, Va, and prothrombin sufficient for effective production of thrombin. Cryoelectron microscopy revealed that annexin V binding to large vesicles caused planar facets, indicating the formation of large sheets of clustered annexin V. Apparently, the formation of these two-dimensional arrays is promoted by calcium and hampered by high surface curvature. It is speculated that the complete inhibition (greater than 99%) of prothrombinase activity by annexin V is caused by the reduced lateral mobility of prothrombin and factor Xa in rigid sheets of annexin V covering the membrane.     

Fast-Growing, Aerobic, Heterotrophic Bacteria from the Rhizosphere of Young Sugar Beet Plants

Fast-growing, aerobic, heterotrophic bacteria from the root surface of young sugar beet plants were inventoried. Isolation of the most abundant bacteria from the root surface of each of 1,100 plants between the second and tenth leaf stage yielded 5,600 isolates. These plants originated from different fields in Belgium and Spain. All isolates were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total cellular proteins. Comparison of protein fingerprints allowed us to inventory the bacteria of individual plants of different fields or leaf stages and to analyze the composition and variability of the rhizobacterial population of young sugar beet plants. Each field harbored a specific population of bacteria which showed a highly hierarchic structure. A small number of bacteria occurring frequently at high densities dominated in each field. The major bacteria were identified as Pseudomonas fluorescens, Xanthomonas maltophilia, Pseudomonas paucimobilis, and Phyllobacterium sp. The former three species showed a high genetic variability as they were represented by different protein fingerprint types on the same or different fields or leaf stages. Twinspan analysis and relative abundance plots showed that the structure and composition of the bacterial populations varied strongly over time. Pseudomonads were typically early colonizers which were later replaced by X. maltophilia or Phyllobacterium sp.