Extent and high frequency of a short conversion between the human Aγ and Gγ fetal globin genes

Summary Southern blotting and DNA sequencing after polymerase chain reaction (PCR) amplification provide evidence for the frequent occurrence (in 7 out of 24 chromosomes) of a short conversion GA in the 3 end of the human fetal A globin gene. This short conversion is characterized by the presence, 3 nucleotides downstream from the termination codon of the A gene, of the TCAC sequence that is normally present at the equivalent position at the 3 end of the G gene; it is therefore identical to a conversion already described. Interestingly, we have found that this conversion is associated with the presence of theHindIII polymorphic restriction site in the A IVS2, occuppying an equivalent position in both the G and A genes. Our observations strengthen the hypothesis that the presence of the HindIII polymorphic restriction site in A IVS2 and the presence of the sequence TCAC at the 3 end of the A gene might be the result of a single conversion event.     

Juvenile colour polymorphism in the red rock crab,Cancer productus: patterns,causes, and possible adaptive significance

Juveniles of the common red rock crab of the Northeastern Pacific, Cancer productus, display a stunning diversity of colours and patterns, while adults all have the same drab colouration. Although this is widely known, key questions remain: (1) Does the frequency of different juvenile colours or patterns vary among collection sites or seasonally? (2) Does juvenile colour polymorphism reflect genetic heterogeneity or phenotypic plasticity in response to variable environmental conditions? (3) Do juveniles of different colours or patterns prefer substrata of different heterogeneity or brightness? We therefore: (i) described the variation in colour and pattern of juvenile C. productus; (ii) tested for associations between colour/pattern morphs and crab size, collection site, and season, in the field; (iii) conducted preliminary tests for habitat preferences (background colour, substratum type, light level) of different colour/pattern morphs in laboratory experiments, and (iv) tested the effect of diet (mussels versus shrimp) and feeding rate (high versus low) on juvenile colour/pattern. We describe 30 phenotypes that embrace a wide range of colour and pattern variants. The proportions of these phenotypes did not vary significantly among four collection sites, but they did vary significantly with season: over the summer and fall, juvenile colour and pattern variation was gradually replaced by the uniform adult colouration. The number of crabs displaying adult colouration also increased with crab size. Laboratory experiments suggest no significant preferences of different juvenile morphs for different backgrounds, substrata, or light levels. Diet (mussels versus shrimp) and feeding frequency had no effect on colour/pattern. Collectively, these results, although limited in scope, are not consistent with two likely hypotheses that could explain the extensive colour and pattern variation in juvenile C. productus: (i) selection for background matching by different cryptic forms and (ii) direct effects of diet or feeding rate on colour or pattern. Most probably, the large variety of different juvenile morphs is a result of frequency-dependent selection in which abundant variants are attacked disproportionately often and rarer forms are favoured. Juvenile colour polymorphism in C. productus may reduce the vulnerability to visual predators, impede the formation of a search image, and consequently decrease the risk of predation during the juvenile stages.     

Longitudinal Changes in Total Brain Volume in Schizophrenia: Relation to Symptom Severity,Cognition and Antipsychotic Medication

Studies show evidence of longitudinal brain volume decreases in schizophrenia. We studied brain volume changes and their relation to symptom severity, level of function, cognition, and antipsychotic medication in participants with schizophrenia and control participants from a general population based birth cohort sample in a relatively long follow-up period of almost a decade. All members of the Northern Finland Birth Cohort 1966 with any psychotic disorder and a random sample not having psychosis were invited for a MRI brain scan, and clinical and cognitive assessment during 1999–2001 at the age of 33–35 years. A follow-up was conducted 9 years later during 2008–2010. Brain scans at both time points were obtained from 33 participants with schizophrenia and 71 control participants. Regression models were used to examine whether brain volume changes predicted clinical and cognitive changes over time, and whether antipsychotic medication predicted brain volume changes. The mean annual whole brain volume reduction was 0.69% in schizophrenia, and 0.49% in controls (p = 0.003, adjusted for gender, educational level, alcohol use and weight gain). The brain volume reduction in schizophrenia patients was found especially in the temporal lobe and periventricular area. Symptom severity, functioning level, and decline in cognition were not associated with brain volume reduction in schizophrenia. The amount of antipsychotic medication (dose years of equivalent to 100 mg daily chlorpromazine) over the follow-up period predicted brain volume loss (p = 0.003 adjusted for symptom level, alcohol use and weight gain). In this population based sample, brain volume reduction continues in schizophrenia patients after the onset of illness, and antipsychotic medications may contribute to these reductions.     

3D modeling and characterization of the human CD115 monoclonal antibody H27K15 epitope and design of a chimeric CD115 target

The humanized monoclonal antibody H27K15 specifically targets human CD115, a type III tyrosine kinase receptor involved in multiple cancers and inflammatory diseases. Binding of H27K15 to hCD115 expressing cells inhibits the functional effect of colony-stimulating factor-1 (CSF-1), in a non-competitive manner. Both homology modeling and docking programs were used here to model the human CD115 extracellular domains, the H27K15 variable region and their interaction. The resulting predicted H27K15 epitope includes mainly the D1 domain in the N-terminal extracellular region of CD115 and some residues of the D2 domain. Sequence alignment with the non-binding murine CD115, enzyme-linked immunosorbent assay, nuclear magnetic resonance spectroscopy and affinity measurements by quartz crystal microbalance revealed critical residues of this epitope that are essential for H27K15 binding. A combination of computational simulations and biochemical experiments led to the design of a chimeric CD115 carrying the human epitope of H27K15 in a murine CD115 backbone that is able to bind both H27K15 as well as the murine ligands CSF-1 and IL-34. These results provide new possibilities to minutely study the functional effects of H27K15 in a transgenic mouse that would express this chimeric molecule.     

Unnatural RNA display libraries

Combinatorial peptide and protein libraries have now been developed to accommodate unnatural amino acids in a genetically encoded format via in vitro nonsense and sense suppression. General translation features and specific regioselective and stereoselective properties of the ribosome endow these libraries with a broad chemical diversity. Alternatively, amino acid residues can be chemically derivatized post-translationally to add preferred functionality to the encoded peptide. All of these efforts are advancing combinatorial peptide and protein libraries for enhanced ligands against biological targets of interest.     

Pentacyclic triterpenoids from Freziera sp. that inhibit DNA polymerase beta

In a survey of crude plant extracts for DNA polymerase 1 inhibitors, a methyl ethyl ketone extract prepared from Freziera sp. exhibited potent inhibition of DNA polymerase beta. Bioassay-guided fractionation of the extract, guided by an assay to detect DNA polymerase beta inhibition, resulted in the isolation of six active pentacyclic triterpenoids (1-6). These triterpenoids had IC50 values ranging from 7.5 to 16 microM in the presence of bovine serum albumin (BSA) and 2.6-5.8 microM in the absence of BSA, consistent with the possibility that these inhibitors may be of use in vivo.