We have characterized the copy number, organization, and genomic modification of DNA sequences within and flanking several maize genes. We found that highly repetitive DNA sequences were tightly linked to most of these genes. The highly repetitive sequences were not found within the coding regions but could be found within 6 kb either 3' or 5' to the structural genes. These highly repetitive regions were each composed of unique combinations of different short repetitive sequences. Highly repetitive DNA blocks were not interrupted by any detected single copy DNA. The 13 classes of highly repetitive DNA identified were found to vary little between diverse Zea isolates. The level of DNA methylation in and near these genes was determined by scoring the digestibility of 63 recognition/cleavage sites with restriction enzymes that were sensitive to 5-methylation of cytosines in the sequences 5'-CG-3' and 5'-CNG-3'. All but four of these sites were digestible in chromosomal DNA. The four undigested sites were localized to extragenic DNA within or near highly repetitive DNA, while the other 59 sites were in low copy number DNAs. Pulsed field gel analysis indicated that the majority of cytosine modified tracts range from 20 to 200 kb in size. Single copy sequences hybridized to the unmodified domains, while highly repetitive sequences hybridized to the modified regions. Middle repetitive sequences were found in both domains.

The authors tabulate and analyze cases of bacterial intracranial aneurysm documented since 1954, and add four of their own. In 85 cases the overall mortality was 46%. Elimination of patients dying before reaching the hospital makes this figure spuriously low. Figures for patients hospitalized for endocarditis before neurological symptoms occurred suggest a true mortality of 80% from aneurysms that rupture and 30% if the aneurysm remains intact. Multiple reports of spontaneously resolving, enlarging, diminishing, multiple, and sequentially appearing aneurysms, all of which occurred in our fourth case, clarify the need for complete and sequential angiography. Computerized tomographic (CT) scanning in this disease has not been reported, but our experience with these scans demonstrates considerable potential value.A protocol of complete cerebral angiography and CT scanning of these neurologically asymptomatic patients is proposed, in order to assess the true incidence of bacterial intracranial aneurysm, to learn more of its natural history, and to prevent some neurological catastrophes. KEY WORDS9 bacterial endocarditis 9 cerebral aneurysm 9 cerebral angiography 9 cerebral hemorrhage 9 infectious aneurysm mycotic aneurysm 9 subarachnoid hemorrhage

A gene coding for proteinase inhibitor I, whose expression is induced in tomato leaves (Lycopersicon esculentum L. var. Bonny Best) in response to wounding or insect attacks, was isolated from a genomic library and characterized. The nucleotide sequence revealed that the gene is complete and encodes the sequence of an inhibitor I cDNA that was previously isolated from a cDNA library prepared from wound-induced mRNA from tomato leaves. This gene is located 13.1 kilobase pairs (kbp) upstream from an inhibitor II gene. The wound-inducible gene is interrupted by two intervening sequences of 445 and 404 bp, situated within the codons of amino acids 17 and 47, respectively, of the open reading frame. In addition to the presence of putative regulatory sequences, TATAAA and CCACT, two copies of an imperfect direct repeat approximately 100 bp long were identified in the 5'-flanking region. Phylogenetic comparisons of wound-inducible inhibitor I genes within the genomes of various Lycopersicon species revealed that the repeat is found in seven ancestral species of tomato.

The scientific understanding of the biology of human brain tumors has advanced in large part through the use of animal models. For most of this century, investigators have been evaluating the inciting factors in brain tumor development, and applying this knowledge to direct tumor growth in laboratory animals. Virus-induced, carcinogen-induced, and transplant-based models have been vigorously investigated. As knowledge of the molecular biology of neoplasia has advanced, transgenic technology has been introduced. The authors review the development of animal models for brain tumor, and focus on the role of transgenic models in elucidating the complex process of central nervous system neoplasia.

A s e r i e s of large-scale f i r e suppression t e s t s was conducted for two d i f f e re n t commodities stored in s t e e l racks of d i f f e r e n t heights, and were analyzed using a global heat balance model. In these t e s t s , water was applied uniformly on top of the storage array a t selected f i r e s i z e s t o determine the f i r e s u p p r e s s i b i l i t y f o r a commodity a t a given storage height. A f i r e suppression parameter was used t o correlate the f i r e suppression r e s u l t s of these t e s t s . The f i r e suppression parameter is a function of fuel d e n s i t y , f u e l s p e c i f i c heat, ignition temperature, heat of combustion, burning r a t e , heat of pyrolysis, and water application r a t e . The data indicate t h a t the combustible packaging and overall storage arrangement have s i g n i f i c a n t impact on the magnitude of the c r i t i c a l water density f o r f i r e suppression. KEYWORDS: water-based f i r e suppression.