Easier detection of invertebrate "identification-key characters" with light of different wavelengths

Evolutionary arms-races between avian brood parasites and their hosts have typically resulted in some spectacular adaptations, namely remarkable host ability to recognize and reject alien eggs and, in turn, sophisticated parasite egg mimicry. In a striking contrast to hosts sometimes rejecting even highly mimetic eggs, the same species typically fail to discriminate against highly dissimilar parasite chicks. Understanding of this enigma is still hampered by the rarity of empirical tests - and consequently evidence - for chick discrimination. Recent work on Australian host-parasite systems (Gerygone hosts vs. Chalcites parasites), increased not only the diversity of hosts showing chick discrimination, but also discovered an entirely novel host behavioural adaptation. The hosts do not desert parasite chicks (as in all previously reported empirical work) but physically remove living parasites from their nests. Here, I briefly discuss these exciting findings and put them in the context of recent empirical and theoretical work on parasite chick discrimination. Finally, I review factors responsible for a relatively slow progress in this research area and suggest most promising avenues for future research.     

Evaluation of a commercial E<Superscript>rns</Superscript>-capture ELISA for detection of BVDV in routine diagnostic cattle serum samples

Background  

Bovine viral diarrhoea virus (BVDV) is an important pathogen in cattle. The ability of the virus to cross the placenta during early pregnancy can result in the birth of persistently infected (PI) calves. These calves shed the virus during their entire lifespan and are the key transmitters of infection. Consequently, identification (and subsequent removal) of PI animals is necessary to rapidly clear infected herds from the virus. The objective of this study was to evaluate the suitability of a commercial E^rns-capture ELISA, in comparison to the indirect immunoperoxidase test (IPX), for routine diagnostic detection of BVDV within a control programme. In addition, the effect of passive immunity and heat-inactivation of the samples on the performance of the ELISA was studied.     

Crystallization of O6-methylguanine-DNA methyltransferase from Escherichia coli

The 19,000 Mr C-terminal domain of the Escherichia coli ada gene product that contains O6-methylguanine-DNA methyltransferase DNA repair activity has been crystallized in a low-salt environment. The crystals, which diffract to 2.3 A (1 A = 0.1 nm), are suitable for detailed structural studies. The space group is P21 with unit cell dimensions a = 46.3 A, b = 45.8 A, c = 46.9 A and beta = 113.3 degrees.     

Neurotensin is produced by and secreted from classic small cell lung cancer cells

The presence of neurotensin in various human tumor cell lines was investigated by radioimmunoassay. High concentrations (0.06-5.1 pmol/mg protein) were detected in 50% of the classic but not variant small cell lung cancer or other human tumor cell lines examined. Biochemical studies indicated that the main peak of immunoreactivity coeluted with synthetic neurotensin using gel filtration and high pressure liquid chromatography techniques. Also, the rate of neurotensin secretion increased approximately 2-fold when theophylline was added which elevated intracellular levels of cAMP 4-fold. Because neurotensin is present in and secreted from many classic small cell lung cancer cells, it may function as a regulatory peptide in this disease.     

Octapeptide analogues of somatostatin inhibit the clonal growth and vasoactive intestinal peptide-stimulated cyclic AMP formation in human small cell lung cancer cells.

Two endocrinologically active octapeptide analogues (BIM-23014 C and BIM-23034) of somatostatin (SRIF) containing either an N- or C-terminal 3-(2-naphthyl)-D-Ala residue were examined for their ability to inhibit the in vitro receptor binding, clonal growth, and vasoactive intestinal peptide (VIP)-stimulated cyclic AMP formation in human small cell lung cancer cell (SCLC) line NCI-H345. Both SRIF peptides inhibited [125I]SRIF(Tyr11)-14 binding with IC50 values in the low nM range. Colony formation in the in vitro SCLC growth assay was also inhibited in the same concentration range, as was VIP-stimulated cyclic AMP formation. Therefore, octapeptide analogues of SRIF function as SCLC SRIF receptor agonists.     

The IRMM—International Measurement Evaluation Program (IMEP)

The aim of the IRMM—International Measurement Evaluation Program (IMEP) is to test out a possible realization of international measurement comparability for field laboratories through traceability of their measurements to the SI Unit for amount of substance: the mole. In IMEP-3, 10 different trace elements, B, Ca, Cd, Cu, Fe, K, Li, Pb, Rb, and Zn, were determined in a synthetic and a natural water by participating laboratories using their routine methods and graphically compared (in coded form) to certified values, established by IRMM and NIST using an isotope-specific method (Isotope Dilution Mass Spectrometry, Neutron Activation Analysis). The number of participants was 70; 64 laboratories have reported results. The results show a spread of more than 50% asymmetrically around the certified value. The Youden graphs allow evaluation of the overall performance of the laboratories in the IMEP-3 round.

     

Kinetics and mechanism of the sensitized photodegradation of lignin model compounds.

The kinetics of the sensitized photodegradation of a variety of well-defined lignin model compounds was studied to determine the mechanisms responsible for lignin's photochemically-mediated oxidation. Monomeric and dimeric models representing lignin's phenolic end groups and nonphenolic dimers representing its inner core were studied. It was determined that the rate constants for the reaction of the deprotonated phenolic models with singlet oxygen (1O2) range from 0.96 to 7.2 x 10(7) M(-1) s(-1). The models were substituted with zero, one, or two electron-donating methoxy groups on both aryl rings and, while the rate constants showed little dependence on the substitution of the nonphenolic ring, the rate constants increased dramatically with increasing methoxy substitution of the phenol. Reaction between these deprotonated models and 1O2 is thus proposed to occur at the phenolate ring. Under neutral conditions, it was observed that the phenolic models react with excited state sensitizer, with this reaction also occuring at the phenol ring. The sum of the rate constants for quenching of and reaction with excited state sensitizer by lignin model compound ranges from 5.4 to 75 x 10(7) M(-1) s(-1). This study corrects previous reports that attribute the sensitized degradation of neutral lignin model compounds to reaction with 1O2. A nonphenolic aromatic ketone inner-core model was observed to undergo direct photolysis, and its reduced analog was not degraded by direct photolysis or reaction with 1O2 or excited state sensitizer. The oxidized inner-core model was also shown to be able to act as a sensitizer for the degradation of a phenolic lignin model compound.     

Oculomotor neuroblast migration in the chick embryo in the absence of tecto-tegmental fibers.

This study investigated a hypothesized relationship between the migration of the oculomotor complex, particularly the ventromedial subnucleus, and the presence of the tecto-tegmental fiber system in the chick embryo. It has been suggested that the presence of these fibers at the time of the initiation and continuation of neuroblast migration in this system might serve as some sort of stimulus influencing or guiding this migration. In order to examine this hypothesis, the dorsal midbrain was ablated in stage 12 embryos, thus removing the source of the tecto-tegmental fibers prior to the development of the oculomotor complex. The results indicated that in the complete absence of the tecto-tegmental fibers, all oculomotor subnuclei migrated normally, attained their normal terminal locations, and appeared to differentiate normally. These results are discussed in relation to other studies of possible extracellular influences during early neurogenesis and the possible importance of within-system versus without-system influences is considered.