Hyporheic biofilms — a potential food source for interstitial animals

Glass-beads (diam. = 250 μm) were buried 10 cm deep in the sediment of a stream. After an exposure of eight weeks, bacterial densities on the beads varied between 2.7 × 10⁵ and 2.4 × 10⁷/cm², and the length of the fungal mycelium between 0.2 and 5.3 mm/cm². Bacterial densities did not show any correlation with the DOC content of the water, but were positively correlated with respiration on the beads. Fungal mycelium was negatively correlated with water temperature. Acid hydrolysis of stream-exposed beads released sugars and amino acids, whose combined carbon content exceeded that of the microbial cells by a factor of at least 4. Gut extracts of Gammarus tigrinus and Tipula caloptera released amino acids and sugars from stream-exposed beads.     

Termination region in rRNA genes from a eucaryotic thermophile, Thermomyces lanuginosus.

S1 mapping of the termination region in the ribosomal DNA from a thermophilic fungus, Thermomyces lanuginosus, revealed three distinct termini corresponding to the mature 25S rRNA, a precursor that is 19 nucleotides longer and corresponds to the 37S precursor in yeast cells, and a putative termination site at +96 that bears a limited sequence homology with the SalI box of mammalian cells. An estimate of the secondary structure suggested that the three termini are in close proximity, a feature that may be essential to precursor termination and maturation. The results raise questions regarding recently reported relationships between ribosomal DNA termination and spacer enhancer elements in fungi.     

Intrinsic potential for high fetal hemoglobin production in a Druze family with β-thalassemia is due to an unlinked genetic determinant

Summary The mechanism for elevated production of fetal hemoglobin (Hb F) in a Druze patient with °-thalassemia intermedia was investigated. Heterozygous family members exhibited normal Hb F levels, suggesting that the increase in -gene expression in the propositus may be partly due to anemic stress. Erythroid progenitors of these family members cultured in vitro [burst forming units (erythroid); (BFUe)] showed elevated synthesis of Hb F, indicating the existence of a genetically determined intrinsic capacity for high Hb F production in this family. The propositus was found to be homozygous for a IVS2-position 1 mutation, on the background of Mediterranean haplotype I, which is not known to be linked to high Hb F production. Moreover, extensive molecular studies of the -globin gene cluster, including sequence analysis of the promoter regions of the -globin genes, did not reveal any cisacting mechanism that could account for the high Hb F production in the propositus. A young niece of the propositus with °-thalassemia major was recently discovered, who was homozygous for the same -globin allele and haplotype as the propositus. However, unlike her uncle, she does not have a high Hb F level and presents with a severe clinical course. Her inability to produce high Hb F suggests that the genetic determinant for increased -gene expression in the propositus is unlinked to the -globin gene cluster.     

Hair morphology and systematics ofPhysalis (Solanaceae)

Hair morphology was exammed on developing seedlings and mature plants of ten species from five of seven series inPhysalis. The taxonomic importance of hair development and the distribution of hair types then was evaluated with respect to other comparative data. Two classes of hair types were observed, as found in earlier investigations ofSolanum andRhododendron. The first hair class comprises a sequence from unbranched hairs to dendroid-stelliform hairs. Hairs of this class show considerable variability among taxa in size, presence or absence of glandular tips, and presence and degree of branching, and so were useful in making taxonomic comparisons. The second hair class consists of short hairs, each tipped with a multicellular gland. This second hair class was not useful taxonomically because of its lack of variability in morphology and its often rare occurrence on a plant. The taxa studied exhibit distinctive trichome features which serve to distinguish series and, in some cases together with other data, provided new insight into previously enigmatic species relationships.     

Computer-assisted grading of adenocarcinoma in prostatic aspirates

Conventional cytologic grading of fine needle aspirates of prostatic adenocarcinoma has been shown neither to be reproducible nor to correlate well with histologic grading. This study developed a tumor grade classification based on computerized cytomorphometric features and compared the results to conventional grading of companion tissue sections. The image analysis system evaluated architectural features of the aspirates (mainly cell cluster features and interrelationships) as well as nuclear features. Thirty-five prostatic adenocarcinomas (8 well, 19 moderately and 8 poorly differentiated) were evaluated. Discriminant functions based on data collected at medium and high resolution distinguished between aspirates from low-grade (well-differentiated) and high-grade (poorly differentiated) adenocarcinomas with 81% accuracy. Moderately differentiated cancers could not be classified as a distinct group. This study suggests that accurate grading of prostatic adenocarcinoma in fine needle aspirate smears requires the evaluation of medium-resolution features related to specimen cellularity and uniformity or crowding of cell clusters as well as of high-resolution features of nuclear area, perimeter and coarseness of chromatin texture. These findings are compared to those of other schemes for the cytologic grading of prostatic aspirates.     

Translational regulation of somatostatin in cultured sympathetic neurons

Coculture of sympathetic neurons with ganglion nonneuronal cells elevated levels of preprosomatostatin mRNA but did not alter neuronal synthesis, content, or release of somatostatin. Treatment of sympathetic neurons with culture medium conditioned by exposure to ganglion nonneuronal cells similarly elevated preprosomatostatin mRNA. Treatment with conditioned medium elevated somatostatin levels in pure neuronal cultures, but not in neurons cocultured with nonneuronal cells. Conditioned medium also failed to increase peptide levels in neurons cultured on a substratum of killed nonneuronal cells, despite a large increase in preprosomatostatin mRNA. These observations suggest that contact of sympathetic neurons with nonneuronal cell membranes inhibits the increase in peptide synthesis, but not the increase in preprosomatostatin mRNA after treatment with conditioned medium. Thus neuronal interactions with nonneuronal cells regulate somatostatin metabolism at both the mRNA and peptide levels. Regulatory effects on the mRNA and the peptide are separable and do not necessarily occur in parallel, and translational controls may be the rate-limiting factors.     

The GLI-Kruppel family of human genes.

Previous characterization of GLI, a gene found to be amplified and expressed in a subset of human brain tumors, revealed the presence of five tandem zinc fingers related to those of Krüppel (Kr), a Drosophila segmentation gene of the gap class. We have used the GLI cDNA as a molecular probe to isolate related sequences from the human genome. Partial characterization of six related loci, including sequence determination, expression studies, and chromosome localization, revealed that each locus could encode a separate finger protein. The predicted proteins all had similar H-C links, i.e., a conserved stretch of 9 amino acids connecting the C-terminal histidine of one finger to the N-terminal cysteine of the next. On the basis of amino acid sequence and intron-exon organization, the genes could be placed into one of two subgroups: the GLI subgroup (with the consensus finger amino acid sequence [Y/F]XCX3GCX3[F/Y]X5LX2HX3-4H[T/S]GEKP) or the Kr subgroup (with the consensus finger amino acid sequence [Y/F]XCX2CX3FX5LX2HXRXHTGEKP). Unlike GLI or Kr, most of the newly isolated genes were expressed in many adult tissues. The predicted proteins probably control the expression of other genes and, by analogy with Kr and GLI, may be important in human development, tissue-specific differentiation, or neoplasia.