Evaluation of cranial bone suture autotransplants in the growing rabbit

A coronal bone suture segment was autotransplanted into an experimentally created defect in the nongrowing portion of the nasal bone in 12 5-week-old male New Zealand white rabbits. The animals were sacrificed 90 days postoperatively. In most specimens the transplants were well incorporated into the recipient site. The transplanted sutures appeared narrower radiographically, and the bony projections of the sutures were not as long as those seen in control sutures. In each case the transplanted sutural ligament had atrophied, and six of the transplants showed bony union across the sutural space. The results suggest that growth and biomechanical stresses are important for maintenance of the sutural ligament and for the stimulation of bone deposition.     

Genetic mapping of endogenous RD-114 retroviral sequences of domestic cats.

The RD-114 family of endogenous retroviral sequences in domestic cats has been shown to consist of approximately 20 copies of genetically divergent virogenes per haploid genome. The chromosomal localization for four endogenous sequences (RDV1-4) was accomplished by correlating the occurrence of specific feline chromosomes with diagnostic viral DNA fragments in a panel of cat X rodent somatic cell hybrids. Analysis of the hybrid panel revealed that endogenous RD-114 sequences are dispersed on multiple cat chromosomes, that certain proviral segments are polymorphic with respect to the presence or absence of virus, and that a restriction fragment characteristic of inducible RD-114 resides on a single feline chromosome (B3), probably at a single locus.     

New mutations affecting induced mutagenesis in yeast

Previously isolated mutations in baker's yeast, Saccharomyces cerevisiae, that impair induced mutagenesis were all identified with the aid of tests that either exclusively or predominantly detect base-pair substitutions. To avoid this bias, we have screened 11 366 potentially mutant clones for UV-induced reversion of the frameshift allele, his4–38, and have identified 10 mutants that give much reduced yields of revertants. Complementation and recombination tests show that 6 of these carry mutations at the previously known REV1, REV1 and REV3 loci, while the remaining 4 define 3 new genes, REV4 (2 mutations), REV5 and REV6. The rev4 mutations are readily suppressed in many genetic backgrounds and, like the rev5 mutation, impart only a limited deficiency for induced mutagenesis: it is likely, therefore that the REV4⁺ and REV5⁺ gene functions are only remotely concerned with this process. The rev6 mutants have a more general deficiency, however, as well as marked sensitivity to UV and an increased spontaneous mutation rate, properties that suggest the REV6 gene is directly involved in mutation induction. The REV5 gene is located about 1 cM proximal to CYC1 on chromosome X.     

Leghemoglobin-like sequences in the DNA of four actinorhizal plants

Summary A cloned cDNA partial copy of a soybean leghemoglobin mRNA was used to probe genomic DNA of four species of actinorhizal plants. Southern blot hybridization revealed the presence of sequences with homology to the leghemoglobin probe in DNA from Alnus glutinosa, Casuarina glauca, Ceanothus americanus and Elaeagnus pungens. The hybridization patterns of the restriction fragments revealed some fragment size conservation between the DNA of soybean and the DNA of four actinorhizal plants which are taxonomically unrelated to soybean or to each other. The results presented here indicate that globin gene sequences are much more widely distributed in the plant kingdom than has previously been thought. Furthermore, if sequence conservation is actually as high as the restriction fragment patterns suggest, the evolution of the DNA surrounding the globin sequences has been highly constrained.     

Genetic characterization of human c-rel sequences.

We isolated and sequenced a human genomic-DNA segment that is homologous to a portion of v-rel, the transforming gene of reticuloendotheliosis virus (strain T). We also localized the human rel sequences to human chromosome 2 by screening a panel of rodent X human somatic-cell hybrids with the newly described human rel segment.     

The influence of water on CO2 exchange in the lichen Parmelia praesignis Nyl.

Net photosynthetic rates for the lichen Parmelia praesignis Nyl. were obtained as a function of 5 light levels, 5 temperature levels, and of water content as thalli dried from saturated conditions. Data are described as second order polynomials in the light, and as saturation curves in the dark. Rates in the light were depressed at high water contents reaching maximal rates between 110% and 180% water content and declining as thalli dried. Physiological parameters were derived from the drying curves to investigate temperature and light interactions. Dark respiration parameters are the maximal rate, the water content where the rate is half-maximal, the water content at which respiration is zero, and the maximal water efficiency. In the light, parameters are the maximal net photosynthetic rate, the water content at the maximal rate, the water compensation point, the maximal water efficiency, and the sensitivity of net photosynthesis to change in water content.Values of half-maximal rate water contents for respiration were found to increase as temperatures increased. The greatest maximal net photosynthetic rate occurred at higher temperatures as the light intensity increased. In the light, maximal water efficiency and the sensitivity to changes in water content were generally maximal at temperatures yielding the greatest maximal net photosynthetic rates.     

The effects of gonadotropins on metabolism of isolated rat granulosa cells

FSH $\text{in vitro}$, but not LH, increased the O₂ uptake of isolated granulosa cells from 23 day old rats previously treated with DES or with DES and FSH. Dose response studies showed that the cells were most sensitive to FSH when the cellular binding of FSH was highest. LH increased the O₂ uptake of granulosa cells of untreated 30 day old rats. DES treatment inhibited the LH induced rise in O₂ uptake when the rats were implanted with DES capsules unless FSH was injected to induce LH receptors. Addition of dbcAMP $\text{in vitro}$ increased O₂ uptake of granulosa cells from 30 day old rats at concentrations 10X lower than those required to stimulate O₂ uptake in cells from 23 day old rats treated with DES alone.FSH $\text{in vitro}$ increased lactate formation in the absence of added substrates but did not do so when glucose was added to the media. In contrast, LH greatly increased lactate formation with added glucose. Dose response studies showed that less than 0.6 ug/ml LH S21 was effective in increasing lactate above control levels. These data suggest that FSH affects aerobic pathways while LH affects anaerobic pathways in the process of the differentiation of granulosa cells toward luteal cells.It is well known that FSH and LH interact with their target cells in the ovary by binding to specific receptors and that FSH stimulates LH-receptor production (1). Receptor binding by either hormone activates adenylate cyclase (2) raising cyclic adenosine monosphosphate (cAMP) levels (3) and increasing protein kinase activity (4). Such changes probably trigger changes in the major metabolic pathways that support follicular development because cells of corpora lutea have glycogen (5) which is not present in follicular granulosa cells (6–9). Several studies suggest that FSH and LH may regulate metabolic processes in the ovary. LH increases lactate in whole prepuberal ovaries (10,11,12) and also increases the uptake of glucose (13). FSH increases oxygen uptake in chick ovaries (14), rat ovaries (15) and prairie dog ovaries (16). However, only one study has been done using isolated ovarian cells. Hamberger (17) has reported that FSH increased the oxygen uptake of thecal cells of immature rats while LH increased the oxygen uptake of granulosa cells. Since granulosa cells from immature rats are reported to have FSH receptors while theca cells have LH receptors the effects of these hormones appear unclear.The present studies were undertaken to more accurately characterize the actions of FSH, LH, and dibutyryl cAMP (dbcAMP) on the oxygen uptake of isolated granulosa cells and remaining tissues of immature ovaries and to determine the effects of FSH and LH on the production of lactate by granulosa cells.     

Delayed hypersensitivity granuloma formation around Schistosoma mansoni eggs in vitro. III. Granuloma formation and modulation in human Schistosomiasis mansoni

An in vitro model of granuloma formation was used to study the cellular immune responses of Schistosoma mansoni-infected patients. The purposes of this study were to determine the relationship of granulomatous hypersensitivity to S. mansoni eggs in recent, well-defined infections and long-term chronic infections, and to determine the role of T cell subsets (OKT3, 4, and 8) defined by monoclonal antibodies in granulomatous hypersensitivity. Peripheral blood mononuclear cells obtained from patients with recent S. mansoni infections demonstrated increased granulomatous hypersensitivity responses in vitro when compared to peripheral blood mononuclear cells obtained from patients infected for 5 yr or more. The selective removal of infected for 5 yr or more. The selective removal of OKT3+ or OKT4+ cells reduced the ability of peripheral blood mononuclear cells to form granulomas in vitro. Positive selection for OKT4+ T cells produced optimal granulomatous hypersensitivity when compared to that produced by the unfractionated peripheral blood mononuclear cell population. OKT8+ cells demonstrated no ability to form granulomas in vitro. Selective removal of OKT8+ T cells produced variable results in the ability of the remaining peripheral blood mononuclear cells to form granulomas in vitro. These studies demonstrate the feasibility of investigating granulomatous hypersensitivity and immunoregulatory mechanisms operative in S. mansoni-infected patients by using in vitro technology.