Comparison of Effects of Long-term Corticotrophin and Corticosteroid Treatment on Responses of Plasma Growth Hormone,ACTH, and Corticosteroid to Hypoglycaemia

The development of the highly sensitive cytochemical bioassay for ACTH has permitted the measurement of plasma ACTH levels during the insulin hypoglycaemia test (I.H.T.) in patients treated with corticosteroids and corticotrophin. The ACTH, corticosteroid, and growth hormone (GH) responses in the I.H.T. were measured in three groups of 12 rheumatoid arthritis patients. One group was receiving long-term corticotrophin treatment, the second was undergoing long-term corticosteroid treatment, and the third had never received systemic hormone therapy. The increments in plasma ACTH, corticosteroids, and GH were diminished in the corticosteroid-treated group, as were increments in plasma GH and ACTH in the corticotrophin-treated group; but in this group the corticosteroid increment was normal. Examination of the area under the curve of the ACTH response showed that the total amount of ACTH secreted was normal though the rate of secretion was reduced. In the corticosteroid-treated group both rate and total secretion were diminished.     

Isolation and Genetic Analysis of Caulobacter Mutants Defective in Cell Shape and Membrane Lipid Synthesis

In this paper we report the isolation, characterization and genetic analysis of several C. crescentus mutants altered in membrane lipid synthesis. One of these, a fatty acid bradytroph, AE6002, was shown to be due to a mutation in the fatA gene. In addition to the presence of the fatA506 mutation, this strain was found to contain two other mutations, one of which caused the production of a water-soluble brown-orange pigment (pigA) and another which caused formation of helical cells (hclA). Expression of the latter two phenotypes required complex media and both were repressed by glucose. However, the lesions were mapped to loci that are separated by a substantial distance. The hclA and the fatA genes mapped close together, possibly implying that comutation had occurred in AE6002. Data are presented that allow the unambiguous identification of a second Fat gene (fatB) in C. crescentus. The map position of another mutation in membrane lipid biogenesis, the glycerol-3-PO₄ auxotroph gpsA505, was also determined. During this study the flaZ gene was fine-mapped and the positions of proC and rif changed from the previously reported location.     

Perinatal Steroid Treatments Alter Alloparental and Affiliative Behavior in Prairie Voles

This experiment was designed to examine the hypothesis that perinatal manipulation of gonadal or adrenal steroids can alter the subsequent expression of juvenile parental (alloparenting) and affiliative behavior in prairie voles (Microtus ochrogaster). Corticosterone (PRECORT), testosterone (PRE-TP), or oil injections (PRESES) were given on Prenatal Days 12–20 or on Postnatal Days 1–6 (CORT6, TP6, or SES6, respectively). Alloparenting was reduced significantly in females in the CORT6 group and in males in the TP6 group. Sibling affiliative preferences were increased significantly in PRE-TP females and stranger preferences were increased in TP6 and CORT6 females. The results suggest timing is a critical factor determining whether hormones have a facilitative or inhibitory effect on alloparental and affiliative behavior in prairie voles. In this species, corticosterone and testosterone have similar organizational effects on affiliative behavior in females. Alloparental behavior is inhibited by postnatal corticosterone administration in females and by postnatal testosterone administration in males, whereas prenatal steroid administration had no significant effect on alloparenting in either gender.     

Comparative chromosome painting between two marsupials: origins of an XX/XY1Y2 sex chromosome system

Cross-species chromosome painting was used to investigate genome rearrangements between tammar wallaby Macropus eugenii (2n = 16) and the swamp wallaby Wallabia bicolor (2n = 10♀/11♂), which diverged about 6 million years ago. The swamp wallaby has an XX female:XY₁Y₂ male sex chromosome system thought to have resulted from a fusion between an autosome and the small original X, not involving the Y. Thus, the small Y₁ should represent the original Y and the large Y₂ the original autosome. DNA paints were prepared from flow-sorted and microdissected chromosomes from the tammar wallaby. Painting swamp wallaby spreads with each tammar chromosome-specific probe gave extremely strong and clear signals in single-, two-, and three-color FISH. These showed that two tammar wallaby autosomes are represented unchanged in the swamp wallaby, two are represented by different centric fusions, and one by a tandem fusion to make the very long arms of swamp wallaby Chromosome (Chr) 1. The large swamp wallaby X comprises the tammar X as its short arm, and a tandemly fused 7 and 2 as the long arm. The acrocentric swamp wallaby Y₂ is a 2/7 fusion, homologous with the long arm of the X. The small swamp wallaby Y₁ is confirmed as the original Y by its painting with the tammar Y. However, the presence of sequences shared between the microdissected tammar Xp and Y on the swamp wallaby Y₂ implies that the formation of the compound sex chromosomes involved addition of autosome(s) to both the original X and Y. We propose that this involved fusion with an ancient pseudoautosomal region followed by fission proximal to this shared region. Received: 16 October 1996/Accepted: 30 January 1997     

Clinical and Molecular Characterization of Patients with Distal 11q Deletions

Jacobsen syndrome is caused by segmental aneusomy for the distal end of the long arm of chromosome 11. Typical features include mild to moderate psychomotor retardation, trigonocephaly, facial dysmorphism, cardiac defects, and thrombocytopenia, though none of these features are invariably present. To define the critical regions responsible for these abnormalities, we studied 17 individuals with de novo terminal deletions of 11q. The patients were characterized in a loss-of-heterozygosity analysis using polymorphic dinucleotide repeats. The breakpoints in the complete two-generation families were localized with an average resolution of 3.9 cM. Eight patients with the largest deletions extending from 11q23.3 to 11qter have breakpoints, between D11S924 and D11S1341. This cytogenetic region accounts for the majority of 11q⁻ patients and may be related to the FRA11B fragile site in 11q23.3. One patient with a small terminal deletion distal to D11S1351 had facial dysmorphism, cardiac defects, and thrombocytopenia, suggesting that the genes responsible for these features may lie distal to D11S1351. Twelve of 15 patients with deletion breakpoints as far distal as D11S1345 had trigonocephaly, while patients with deletions distal to D11S912 did not, suggesting that, if hemizygosity for a single gene is responsible for this dysmorphic feature, the gene may lie distal to D11S1345 and proximal to D11S912.     

Effect of Carbon Source and the Role of Cyclic Adenosine 3′,5′-Monophosphate on the Caulobacter Cell Cycle

The expression of cell cycle events in Caulobacter crescentus CB13 has been shown to be associated with regulation of carbohydrate utilization. Growth on lactose and galactose depends on induction of specific enzymes. Prior growth on glucose results in a delay in enzyme expression and cell cycle arrest at the nonmotile, predivisional stage. Dibutyryl cyclic adenosine 3',5'-monophosphate (AMP) was shown to stimulate expression of the inducible enzymes and, thus, the initiation of the cell cycle. beta-Galactosidase-constitutive mutants did not exhibit a cell cycle arrest upon transfer of cultures from glucose to lactose. Furthermore, carbon source starvation results in accumulation of the cells at the predivisional stage. The cell cycle arrest therefore results from nutritional deprivation and is analogous to the general control system exhibited by yeast (Hartwell, Bacteriol. Rev. 38:164-198, 1974; Wolfner et al., J. Mol. Biol. 96:273-290, 1975), which coordinates cell cycle initiation with metabolic state. Transfer of C. crescentus CB13 from glucose to mannose did not result in a cell cycle arrest, and it was demonstrated that this carbon source is metabolized by constitutive enzymes. Growth on mannose, however, is stimulated by exogenous dibutyryl cyclic AMP without a concomitant increase in the specific activity of the mannose catabolic enzymes. The effect of cyclic AMP on growth on sugars metabolized by inducible enzymes, as well as on sugars metabolized by constitutive enzymes, may represent a regulatory system common to both types of sugar utilization, since they share features that differ from glucose utilization, namely, temperature-sensitive growth and low intracellular concentrations of cyclic guanosine 3',5'-monophosphate.     

Molecular distribution of zinc in biliary and pancreatic secretions

Rat bile and pancreatic fluid were examined for the presence of low molecular weight zinc complexes. Fluids were collected separately by cannulation, and zinc distribution in collected samples was analyzed by gel filtration on Sephadex G-50. Most of the zinc in bile was associated with low molecular weight zinc complexes; only a small amount of zinc was present in the high molecular weight fraction. In contrast, pancreatic secretions did not contain low molecular weight zinc complexes, but there were considerable amounts of zinc bound to high molecular weight compounds. The addition of zinc to bile resulted in an increased amount of zinc in the low molecular weight fraction, while the addition of zinc to pancreatic fluid resulted primarily in an increase in zinc bound to the high molecular weight components. Like pancreatic fluid, homogenates of pancreatic tissue had no low molecular weight zinc complex. In rats whose bile and pancreatic fluid were removed and not returned into the intestine, the amount of zinc bound to low molecular weight complexes in intestinal homogenates was reduced. This alteration of the molecular distribution of zinc in intestinal homogenates by removal of bile and pancreatic fluid suggests the potential importance of low molecular weight zinc complexes for zinc homeostasis.