We investigated the retroviral/retroposon hypothesis of schizophrenia by generating sequences with PCR primers based on a retroviral sequence recovered by Yee et al. [1998: Schizophr Res 29:92] from a cDNA library from postmortem brain tissue from an individual with psychosis in a genomic region (Xq21.3) that has been tentatively linked to schizophrenia and schizoaffective disorder by Laval et al. [1998: Am. J. Med. Genet. (Neuropsychiatr. Genet.) 81:420-427]. Within the block of homology with Yp that was generated by a transposition between the chimpanzee and Homo sapiens we find two sequences, HS307 and HS408, with a high degree of homology to but not identity with the schizophrenic brain cDNA. The closest match of these three sequences is to a family of retroposons, that has evolved from the HERV-K family of endogenous retroviruses, some members of which (e.g., SINE-R.C2) appear to be specific to the human genome. This element has been reported as a cause of Fukuyama-type muscular dystrophy [Kobayashi et al., 1998: Nature 394:388-392]. Such retroposons, as agents of change in the human genome, provide a strategy for investigating pathogenesis. On account of their genomic location in a region that has been subject to change in the course of hominid evolution, and that may have a relationship to psychosis and/or cerebral asymmetry, we conclude that these particular insertions deserve further investigation.

Vascular endothelial growth factor (VEGF) is a key stimulator of physiological and pathological angiogenesis. VEGF signals primarily through VEGF receptor 2 (VEGFR2), a receptor tyrosine kinase whose expression is found predominantly on endothelial cells. The purpose of this study was to determine the role of VEGFR2 expression in NSCLC cells. NSCLC cells and tissue sections were stained for VEGFR2 expression by immunohistochemistry (IHC). Immunoblotting and ELISA were used to determine the activation and inhibition of VEGFR2 and its downstream signalling pathways. Five-day proliferation assays were carried out in the presence or absence of VEGF. IHC analysis of NSCLC demonstrated tumour cell VEGFR2 expression in 20% of samples. Immunoblot analysis showed expression of VEGFR2 protein in 3/8 NSCLC cell lines that correlated with VEGFR2 mRNA expression levels. VEGF-dependent VEGFR2 activation was apparent in NSCLC cells, and was associated with increased tumor cell proliferation. Cediranib treatment or siRNA against VEGFR2 inhibited VEGF-dependent increases in cell proliferation. Inhibition of VEGFR2 tyrosine kinase activity using cediranib was more effective than inhibition of AKT (MK2206) or MEK (AZD6244) for overcoming VEGFR2-driven cell proliferation. VEGF treatment did not affect cell survival following treatment with radiation, cisplatin, docetaxel or gemcitabine. Our data suggest that a subset of NSCLC tumour cells express functional VEGFR2 which can act to promote VEGF-dependent tumour cell growth. In this tumour subset, therapies targeting VEGFR2 signalling, such as cediranib, have the potential to inhibit both tumour cell proliferation and angiogenesis.

The SINE-R retroposon family has been identified by its relationship with the long terminal repeats (LTRs) of human endogenous retrovirus class K (HERV-K) as a mobile element that has evolved recently in the human genome. Here we examined the recent evolutionary history of this class of elements by a PCR approach to genomic DNA from the African great apes and by phylogenetic analysis including comparison with the HERV K10 parent sequence. With primers derived from a cDNA sequence from human brain, we identified 27 sequences from the chimpanzee and 16 from the gorilla. Phylogenetic comparisons with previously recognized sequences from the human and from the orangutan and gibbon revealed wide overlap of elements across species, suggesting multiple origins in the course of hominoid evolution. Two human elements SINE-R.C2 and HS307 were the furthest removed from the HERV-K10 sequence but these two elements were closely related to three elements from the chimpanzee and four elements from the gorilla. This group of elements (our clusters 14 and 15) appears to have transposed late in hominoid evolution. One element (Ch-M16) showed 99.1% sequence identity with the SINE-R.C2 element, which is human-specific. Thus the SINE-R family appears to have continued to be active in transposition throughout the course of primate evolution.

An increased incidence of psychiatric and structural brain abnormalities in individuals with Klinefelter syndrome (KS, 47 XXY) could be due to the presence of extra copies of X-Y homologous genes that escape X inactivation. Of particular interest are the two brain-expressed genes Protocadherin11XY (PCDH11XY) and the Synaptobrevin-like gene (SYBL1) which have been duplicated from the X chromosome to the Y chromosome to give X-Y homologous gene pairs that are specific to modern humans. We examined the DNA of KS individuals reported recently by DeLisi et al. 2005 and determined the parental origin of the X alleles, the degree of skewed X inactivation and investigated the CpG island methylation status of PCDH11XY and SYBL1 by bisulphite sequencing and quantification of methylated HpaII sites. We used a novel method for quantification of unmethylated CpGs with the restriction enzyme McrBC which cuts methylated but not unmethylated CpGs. The results showed that KS individuals have two methylated and one unmethylated SYBL1 allele whereas PCDH11XY is unmethylated and escapes X inactivation on the extra X chromosome. Overexpression of PCDH11XY in KS is probable and variable escape from inactivation of this Homo sapiens-specific gene could account for some abnormalities in KS. The origin of the parental alleles or their preferential X inactivation was not associated with psychotic symptoms.

S U M M A R YPrimary roots ot Zea mays L., when grown to 100 mm long, may display instahility in the arehiteeture of their meristems. This oeeurs over the whole temperature range from 15 to 35 °C, hut most frequently at the two e.xtremes of the range and is associated with ahnorniaily low ratios hetween rates of mitosis in the proximal tier of the cap eells and rates in the eells of the quiescent centre. Anomalous meristems show either proliferation of the numher of eell layers hetween stelar pole and eap houndary or protrusions of cells derived from the quieseent centre into the eap where they ean spread to form new sets of eap initials. The process ean be repeated, hut there is no evidence to suggest that the originally closed meristem ever operates as an open meristem with only transiently quieseent cells distal to the stelar pole.

No evidence was obtained for gene dosage imbalances in MIC2, PCDHXY and SYBL1 in patients with schizophrenia.

SUMMARYRates of mitosis in each of the four tiers of the cap meristem of primary roots of Zea niavs L. were measured at uniform root length by a stathmokinetic method and compared with rates for other regions of the apices in seedlings growing at between \S and 35 °C. The highest elemental rate of cap cell production in the proximal tier and in the cap meristem as a whole occurs at 26 °C and the proportion of cells supplied by the proximal tier rises from 48 % at \S °C to 90",, at 35 °C. The number of cells in the whole cap and in its meristem decreases with increasing temperature. This is due to the general reduction in the width of root apices with age and growth in length being faster at the higher temperatures. The slimming of the apex is effected by a decline in the proportion of divisions that are longitudinal to the files of eells at the quiescent centre. This is enhanced by a slight but continuous increase in the rate of mitosis in the quiescent centre the higher the temperature (in contrast with the rest of the root whose maximal rate is at 28 °C). The decline results in an increase in the elemental rate for longitudinal divisions in the cap initials from 0-02 to 0-17 cells per cell per day between 15 and 35 °C and a consequent change in the cell pattern iti the cap.

Proteolytic enzyme activities of the wood-decaying basidiomycetes Serpula lacrymans and Coriolus versicolor, have been characterized using azocasein as substrate and by electrophoretic analysis with gelatin-containing polyacrylamide gels (gelatin-SDS-PAGE). In S. /acryinans# intracellular and extracellular azocaseinase activity was optimal at pH 5.6 and was inhibited by pepstatin A. Gelatin-SDS-PAGE revealed two highly active proteinases, 51 and 54 (apparent M, 65000 and 30000, respectively) and two less active enzymes, S2 and 53 (apparent M, 47000 and 43000, respectively). S1, the predominant intracellular proteinase, was present at all ages of the mycelium (tested up t o 3 months). It is active over a broad pH range, with highest activity around neutral pH. As 51 was partially inhibited by 1,lO-phenanthroline, the enzyme was considered t o be a metalloproteinase although EDTA and phosphoramidon had no effect. A proteinase apparently identical t o S 1 was also detected in the medium of older cultures. 54 is a pepstatinsensitive aspartic proteinase; its activity was highly pH-dependent and it was inactive in gelatin gels at pH 50 and above. S2 and 53 were identified as intracellular metalloproteinases, present in relatively young and growing cultures. They were distinct from S1 as they were inhibited by EDTA and phosphoramidon. During starvation-induced autolysis of S. lacrymans, proteinase 51 was the only enzyme present throughout (and the intracellular azocaseinase activity increased), which suggested a likely role of 51 in intrahyphal protein mobilization. 54 is more likely to play a part in extracellular digestion of protein. The azocaseinase activities of cultures of C. versicolor were optimal at pH 7-0 (intracellular) and pH 5 6 (extracellular). Mycelial extracts gave one major band of proteinase activity in gelatin gels, C1 (apparent M, 62-64000). Since the activity was sensitive to inhibitors of both serine and metalloproteinases, there may have been overlapping bands due t o enzymes of both types. Extracellular samples gave a more complex pattern, (five bands, C2-C6, M, 50000-100000). C2 and C4 are PMSF-sensitive proteinases, C5 and C6 are probably metalloproteinases, while C3, which was most active at pH 4.0, was unaffected by any of the inhibitors tested, including pepstatin A. No aspartic proteinase equivalent t o 5. lacrymans 54 appeared t o be produced by C. versicolor. From the information gained about the intracellular or extracellular location of these enzymes, and the conditions under which they are active, an in vivo role may be tentatively ascribed to some of them.