Chromosome 18 analysis by fluorescence in situ hybridization (fish) in human blastomeres of abnormal embryos after in vitro fertilization (ivf) attempt

We performed fluorescence in situ hybridization (FISH) with a chromosome 18-specific probe on human abnormal cleaved embryos, fertilized either by two spermatozoa and exhibiting three pronuclei (3 PN) or normally fertilized and exhibiting two pronuclei (2 PN) with subsequent severe fragmentation and/or blocking. The aim of the study was to evaluate the incidence of chromosome 18 anomalies among these embryos, in order to evaluate the FISH efficiency on such material and to obtain more precise and complete data than those obtained with classical cytogenetic analysis. For the 3 PN cleaved embryos, FISH confirmed the frequent regulation towards diploidy (25 per cent) and the high frequency of mosaics (53 per cent). For the 2 PN blocked or damaged embryos, FISH permitted chromosome evaluation, which was otherwise impossible with classical cytogenetic techniques: we also found a high mosaic frequency (45 per cent) with these embryos. If this frequency were the same for normally developing embryos, it would be a major obstacle to the reliability of either chromosomal or genetic preimplantation diagnosis.     

Symmetry is in the eye of the ‘beeholder’: innate preference for bilateral symmetry in flower-naïve bumblebees

Bilateral symmetry has been considered as an indicator of phenotypic and genotypic quality supporting innate preferences for highly symmetric partners. Insect pollinators preferentially visit flowers of a particular symmetry type, thus leading to the suggestion that they have innate preferences for symmetrical flowers or flower models. Here we show that flower-naïve bumblebees (Bombus terrestris), with no experience of symmetric or asymmetric patterns and whose visual experience was accurately controlled, have innate preferences for bilateral symmetry. The presence of color cues did not influence the bees original preference. Our results thus show that bilateral symmetry is innately preferred in the context of food search, a fact that supports the selection of symmetry in flower displays. Furthermore, such innate preferences indicate that the nervous system of naïve animals may be primed to respond to relevant sensory cues in the environment.     

Hydrolytic and enzymatic degradation of poly(γ-glutamic acid) hydrogels and their application in slow-release systems for proteins

The hydrolytic and enzymatic degradation of newly developed hydrogels, produced by cross-linking purified poly(-glutamic acid) (PGA) with dihaloalkane compounds, was studied and is reported in this paper. Analysis of hydrolysis of the hydrogel as a function of pH indicated that the hydrolysis occurred slowly at neutral pH, but fast in both acidic and alkaline solutions, while the polymer could be hydrolyzed rapidly only in acidic solutions. The ester bonds were more sensitive to hydrolysis than peptide bonds. The biodegradability of the hydrogel and polymer was further confirmed when enzymatic degradation was studied by three enzymes (cathepsin B, pronase E, and trypsin), which were able to cleave both ester and peptide bonds gradually. A slow-release system for porcine somatotropin (pST) formed by using the hydrogel as matrix to entrap the hormone was evaluatedin vitro andin vivo. Results demonstrated that the hydrogel was able to release the hormone for a period of 20–30 days and indicated its potential application in slow-release systems for bioactive materials, especially macromolecules, such as peptides and proteins.     

Reduced Chitinase Activities in Ant Plants of the Genus Macaranga

Many plant species have evolved mutualistic associations with ants, protecting their host against detrimental influences such as herbivorous insects. Letourneau (1998) reported in the case of Piper that ants defend their plants principally against stem-boring insects and also reduce fungal infections on inflorescences. Macaranga plants that were experimentally deprived of their symbiotic Crematogaster ants suffered heavily from shoot borers and pathogenic fungi (Heil 1998). Here we report that ants seem to reduce fungal infections actively in the obligate myrmecophyte Macaranga triloba (Euphorbiaceae), while ant-free plants can be easily infected. We also found extremely low chitinase activity in Macaranga plants. The plants' own biochemical defense seems to be reduced, and low chitinase activity perhaps may represent a predisposition for the evolution of myrmecophytism. These plants are therefore highly dependent on their ants, which obviously function not only as an antiherbivore defense but also as an effective agent against fungal pathogens. Received: 5 August 1998 / Accepted in revised form: 18 November 1998     

Prenatal diagnosis of an intra-abdominal sacrococcygeal teratoma

The prenatal diagnosis of a presacral (type IV) sacrococcygeal teratoma (SCT) is described. The initial ultrasound appearance was suggestive of a lower urinary tract obstruction, but further ultrasonic examination and radiological imaging using contrast medium led to the diagnosis of SCT. This is the first prenatal diagnosis of a totally intra-abdominal SCT.     

Formation factor logging by electrical methods. Comparison of formation factor logs obtained in situ and in the laboratory

In this paper, a new in situ method for obtaining the formation factor, which is essential for the matrix diffusion, is described and tested in intrusive igneous rock. The method is based on electrical resistivity measurements in rock where the pore water and rock resistivities are essential parameters. The method is based on electromigration instead of diffusion as in traditional diffusion experiments. In previous works, quantitative formation factors of rock have been obtained by electrical methods in the laboratory. Here, a similar approach is used in situ. An in situ logging campaign was performed by SKB during 2000 in the 1700-m-deep borehole KLX02 in Laxemar, Sweden. The rock resistivity was measured with the slimhole Dual Laterolog from Antares. The groundwater resistivity was measured with the Difference Flow Meter from Posiva. A formation factor log was obtained with the maximum vertical resolution of 10 cm. In order to validate the log, 100 rock samples were taken from the bore core, and a formation factor log was obtained by using electrical methods in the laboratory. Both direct current (DC) and alternating current (AC) were used. The measurements on the core confirmed that the in situ log was quantitative, but with a possible systematic error. The in situ formation factors were on average about 1/3 to 1/5 of the laboratory formation factors, depending on depth.     

Occurrence and source of brominated organic compounds in surface waters

Monitoring of organic halogen compounds, measured as adsorbable organically bound bromine (AOBr), in an eutrophic lake, which is influenced by treated waste water, revealed repeatedly high concentrations of organobromine compounds in late summer, whereas five times lower values were measured during the rest of the year. It was possible to reproduce the in situ observed AOBr increase in the laboratory. Batch experiments were performed with lake water from two different lakes and an algae culture. It could be shown that the AOBr production is not limited to strong waste water influenced lakes. Furthermore, the AOBr formation requires light and the presence of algae, and thus is most probably biotic in nature. A low content of nutrients favours the formation of organic bromine compounds. To our knowledge this is the first report about the seasonally occurrence of naturally produced organic bromine compounds in lakes/surface waters.