Ultrastructural study of cholecystokinin-like immunoreactivity in endocrine cells of the insect midgut

Summary Electron-microscopic immunocytochemistry for the demonstration of CCK-like material in basal endocrine cells of the midgut of Aeschna cyanea, Locusta migratoria, Carausius morosus and Periplaneta americana was performed by use of the peroxidase-antiperoxidase procedure and the colloidal gold method. Immunoreactive cells appeared scattered among digestive and regenerative cells of the epithelium. Immunoreactivity was specifically detected over round to oval electron-dense granules whose size appeared rather different from species to species. Thus, the average size of 30% (d30) of the largest granules ranged from 312 nm in Periplaneta americana to 159 nm in Carausius morosus with intermediate values in Aeschna cyanea (d30=195 nm) and Locusta migratoria (d30=225 nm).     

Hereditary cystatin C amyloid angiopathy: identification of the disease-causing mutation and specific diagnosis by polymerase chain reaction based analysis

Summary Hereditary cystatin C amyloid angiopathy (HCCAA) is a dominantly inherited disease characterized by amyloidosis, dementia and fatal cerebral hemorrhage of young adults. A method for rapid and simple diagnosis of HCCAA is described. It is based upon oligonucleotide-directed enzymatic amplification of a 275-bp genomic DNA segment containing exon 2 of the cystatin C gene from a blood sample, followed by digestion of the amplification product with AluI. Loss of an AluI recognition site in the amplified DNA segment from HCCAA patients results in a deviating band-pattern at agarose gel electrophoresis, compared with that obtained from normal subjects or unaffected HCCAA family members. In a population of 9 patients with manifest HCCAA, 14 patients with other causes of brain hemorrhage and 16 healthy individuals, the diagnostic procedure displayed a sensitivity and specificity for HCCAA of 100%. Amplified DNA segments from 4 HCCAA patients of four different families were analyzed by nucleotide sequencing; the HCCAA-causing mutation in all families was found to be a single TA substitution in the codon for amino acid residue 68 of cystatin C.     

Seasonal abundance and distribution of Caridea larvae in Isafjord-deep, north-west Iceland

The abundance and distribution of Candea larvae was studiedin Ísafjord-deep, north-west Iceland, at approximatelymonthly intervals from February 1987 to February 1988 Zooplanktonsampling was made at nine stations along the length of the fjord,while temperature and chlorophyll a measurements from one ofthe stations are also presented Larvae of six species occurredin the samples, Eualus pusiolus and Pandalus borealis were mostnumerous, constituting 62 8 and 25 9% of the larvae respectively.The other species were, in declining order of abundance, Pandalusmontagui, Spirontocaris spp. (S spinus and s lilljeborgii) andSabinea septemcarinata. Eualus pusiolus was of highest abundancein the outer and middle parts of the fjord, while P.borealiswas most common in the middle and inner parts The onset of hatchingof all species in April–May appeared closely linked tothe phytoplankton spring bloom, while the temperature in thefjord was by then near the annual low (2–3°C). Exceptfor E pusiolus, of which a small part of the population produceda second brood during the summer, most of the larvae had disappearedfrom the plankton by the middle of August The monthly carapacegrowth of P.borealis larvae during the summer months was estimatedto be 1.0 mm.     

Binding of hexabrachions to heparin and DNA

Hexabrachions are extracellular proteins expressed in certain tissues and at specific points in development. cDNA sequencing has revealed that they contain a region of repeats that are similar to the type III homology units of fibronectin. The corresponding region of fibronectin contains heparin- and DNA-binding domains. We have compared the heparin and DNA binding of hexabrachion secreted by the human glioblastoma cell line U87MG to that of fibronectin. Both proteins bound to heparin-agarose in low salt (0.05 M NaCl) buffers. Using linear salt gradients, hexabrachion was eluted from heparin prior to fibronectin. The addition of 5 mM CaCl2 decreased the affinity of both proteins for heparin, but it had a greater effect upon the binding of fibronectin. Free heparin but not chondroitin sulfate inhibited the binding of both proteins to heparin-agarose. In addition, hexabrachion bound to DNA as fibronectin does, and this binding could be inhibited by heparin but not by chondroitin sulfate. Unlike fibronectin, hexabrachion did not bind to gelatin when samples containing both proteins were passed over gelatin-agarose, also indicating that there was no interaction between hexabrachion and fibronectin. In contrast to hexabrachion isolated from brain, the protein secreted by the human glioblastoma cell line U87MG does not bear the HNK-1 epitope which is on a carbohydrate that can mediate interactions between cells.     

Ca2+-phospholipid-dependent protein kinase from the rat liver: physico-chemical properties and kinetic parameters

Ca2+, a phospholipid-dependent protein kinase, was isolated from the rat liver and the dependence of this enzyme on different conditions of the phosphotransferase reaction and substrate specificity was studied. The amino acid analysis was performed using "Aminochrom-2" (Hungary).     

Kinetic characteristics of Ca2+-phospholipid-dependent protein kinase from the rat liver in the early stages after x-ray irradiation]

The changes of kinetic characteristics (apparent Km and Vmax) of the Ca2+ phospholipid-dependent protein kinase (protein kinase C) from the rat liver for substrates ATP and histone Hl 2 and 24 hours after total X-ray irradiation have been established. The obtained results evidence for the important role of these changes in early radiosensitivity of protein kinase C.     

Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS)

Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1^st January 2000 to 31^st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September–May) and mixing (June–August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore—offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria.     

Optimization of heterologous production of the polyketide 6-MSA in Saccharomyces cerevisiae

Polyketides are a group of natural products that have gained much interest due to their use as antibiotics, cholesterol lowering agents, immunosuppressors, and as other drugs. Many organisms that naturally produce polyketides are difficult to cultivate and only produce these metabolites in small amounts. It is therefore of general interest to transfer polyketide synthase (PKS) genes from their natural sources into heterologous hosts that can over-produce the corresponding polyketides. In this study we demonstrate the heterologous expression of 6-methylsalicylic acid synthase (6-MSAS), naturally produced by Penicillium patulum, in the yeast Saccharomyces cerevisiae. In order to activate the PKS a 4'-phosphopantetheinyl transferase (PPTase) is required. We therefore co-expressed PPTases encoded by either sfp from Bacillus subtilis or by npgA from Aspergillus nidulans. The different strains were grown in batch cultures. Growth and product concentration were measured and kinetic parameters were calculated. It was shown that both PPTases could be efficiently used for activation of PKS's in yeast as good yields of 6-MSA were obtained with both enzymes.