Allozyme evidence for genetic autopolyploidy and high genetic diversity in tetraploid cranberry, Vaccinium oxycoccos (Ericaceae)

Polyploidy has been important in the evolution of angiosperms and may significantly affect population genetic diversity and structure. Nineteen isoenzyme loci were studied in diploid and tetraploid populations of Vaccinium oxycoccos (Ericaceae), and the results are compared with data previously reported for the related V. macrocarpon. Diploid V. oxycoccos and V. macrocarpon were readily discriminated based on their allozymic variation. No evidence for fixed heterozygosity was found in tetraploid V. oxycoccos. In contrast, all polymorphic loci exhibited both balanced and unbalanced heterozygotes, with some individuals exhibiting a pattern consistent with the presence of three alleles. These results support an autopolyploid origin for tetraploid V. oxycoccos. However, tetraploid V. oxycoccos possessed a suite of alleles not found in diploid V. oxycoccos; half of these alleles were shared with V. macrocarpon. This suggests that autotetraploid V. oxycoccos may have undergone hybridization with V. macrocarpon or that the autotetraploid retained the genetic variation present in an ancestral diploid species. Following theoretical expectations, proportion of polymorphic loci, mean number of alleles, and observed heterozygosity were significantly higher for the autotetraploid than for the diploid. Mean inbreeding (F(IS)) was similar for diploid and tetraploid V. oxycoccos. The latter exhibited population differentiation (F(ST)) exceeding both diploid species.

Aldose reductase and IGF-I gene expression in aortic and arteriolar smooth muscle during hypo- and hyperinsulinemic diabetes

Two genes whose expression is likely to be altered during diabetes mellitus are aldose reductase (AD) and insulin-like growth factor-I (IGF-I). We proposed that gene expression of AD is increased in vascular smooth muscle during diabetes mellitus due to hyperglycemia, while IGF-I expression is decreased in insulin-deficient diabetes and elevated in insulin-resistant diabetes. The mRNA for both was measured in the renal glomerulus, in the vascular smooth muscle of large arterioles from the brain, kidney, and small intestine, and in the aorta of hypoinsulinemic streptozotocin (STZ)-treated rats and hyperinsulinemic Zucker diabetic fatty (ZDF) rats. Quantitative in situ hybridization was used to determine variations in expression. Expression of the AD gene was unchanged in STZ and ZDF rats, except for a decrease of about 50% in glomeruli and renal smooth muscle of STZ diabetic rats. Expression of IGF-I generally decreased in vascular smooth muscle of insulin-depleted STZ diabetic rats, but was normal in hyperinsulinemic ZDF rats. The data indicate that decreased expression of the AD gene is a specific problem in renal vascular smooth muscle and glomeruli in the insulin-depleted STZ model of diabetes. The expression of the IGF-I gene in vascular muscle was decreased in hypoinsulinemic diabetic animals, but did not increase in hyperinsulinemic diabetic rats.

Reduced levels of histone H3 acetylation on the inactive X chromosome in human females

Novel antibodies were generated that are highly selective for either acetylated or unacetylated isoforms of histone H3, or the acetylated form of histone H4 in organisms as diverse as Tetrahymena and humans. Using these antibodies as pair-wise sets in immunocytological analyses, we demonstrate that the inactive X chromosome is hypoacetylated for both histone H3 and H4 in female mammalian cells, whereas the antibody that recognizes the unacetylated form of histone H3 identifies all chromosomes uniformly. These data verify and extend previous results and suggest that hypoacetylation of core histones may be a general feature of the chromatin along the inactive X chromosome.

Ultrastrucure of the superior oblique tendon

Individual collagen fibers in the superior oblique tendon of patients with superior oblique palsy studied at 60,000x with transmission electron microscopy are fewer in number and larger in diameter when compared to normal fibers. The relationship of these changes to function and to gross morphologic changes are not clear.

Postnatal maturation of rabbit renal collecting duct. II. Morphological observations

The renal collecting duct exhibits cellular heterogeneity. An ultrastructural analysis of this nephron segment during maturation has been performed to determine morphological characteristics of developing principal and intercalated cells (IC). Apical surface features and cytoplasmic ultrastructure were best revealed by scanning electron microscopy and by transmission electron microscopy, respectively. Morphological maturity was assessed by comparing measurements of apical perimeter, vesicular profiles, and mitochondrial volume percent. In mature cortical collecting duct (CCD), approximately 30% of total cells were rich in mitochondria and generally dark in matrix staining, i.e., IC. Most IC in outer cortex were microvillated, whereas in inner cortex most IC were microplicated with interspersed microvilli. Only approximately 16% of cells in outer medullary collecting duct (OMCD, outer stripe) were IC, with light cytoplasm and large protruding apical surfaces covered exclusively with microplicae. Neonatal CCDs showed no IC in outer cortex; a single type of principal-like cell was found in outer cortical region. Neonatal IC in both CCDs and OMCDs showed smaller apical perimeters, vesicular volumes, and mitochondrial volume percents than did mature IC. Whereas the number of cortical IC was reduced in the newborn, IC were present in mature numbers in OMCD and appeared relatively more mature than did IC of CCD. Some (approximately 10%) of IC in neonatal CCD did not show an identifiable apical surface pattern. Principal cells from both newborn CCD and OMCD were also morphometrically immature. It is clear that the neonatal collecting duct undergoes postnatal proliferation and differentiation.

Shock wave lithotripsy-induced renal injury

Both clinical and experimental reports clearly show that shock wave lithotripsy (SWL) causes acute renal effects in a majority, if not all, treated kidneys. SWL-induced acute renal damage may result in severe injury to the nephron, microvasculature, and the surrounding interstitium. In addition, at least three chronic adverse effects have been identified when shock waves are administered at a therapeutic dose. These include (1) an accelerated rise in arterial blood pressure, (2) a decrease in renal function, and (3) an increased rate of stone recurrence. The clinical and experimental data that document tissue injury as a result of shock wave treatment are compelling, but have not allowed us to determine the factors responsible for the adverse acute side effects or to identify conditions that may predispose a patient to serious long-term health problems. Thus, there is an urgent need for incisive, fundamental experimental studies to establish the safe limits for shock wave delivery. To accomplish this goal, animal experimentation is required so that the time course and severity of acute and chronic alterations can be followed in a model that closely mimics human renal structure and functions. The minipig provides this model.

The effects of convulsant doses of penicillin on primary afferents, dorsal root ganglion cells, and on 'presynaptic' inhibition in the spinal cord

Intracellular recordings were made from neurons in dorsal root ganglia (DRG) of rats, isolated in vitro. The depolarization of DRG cells caused by the application of gamma-aminobutyric acid (GABA) diminished reversibly when penicillin (0.08--2.0 mM) was added to the bathing fluid. The decrease of the input resistance of DRG cells measured during GABA perfusion was also depressed in the presence of penicillin, but no evidence of a shift of the reversal potential of the GABA-induced depolarization was found. Nor did penicillin (up to 10 mM) cause a change in the voltage-current function, in electrical excitability, in the inclination to repetitive firing, bursting discharge, or after discharge. In decapitate cat preparation the amplitude of the negative dorsal root potential (DRP or DR V) diminished by 0--50% after the i.v. administration of 0.5--1.0 X 10(6) I.U./kg (the convulsant dose) of penicillin. Post-tetanic depression of the DRP was aggravated by penicillin. The degree of depression of the DRP bore no relationship to the promptness of the eruption, and to the intensity, of the seizure activity induced by penicillin. The rates of rise and fall of the negative DRP (DR V) were consistently slowed, the positive DRP (DR VI) reduced, and the dorsal root reflex (DRR) blocked by penicillin. Inhibitory reflex effects presumed to be presynaptic were either enhanced or unchanged, never depressed by penicillin. This was seen when inhibitory function was gauged by monosynaptic reflex amplitude, and also from the inhibition of ventral root electrotonic excitatory postsynaptic potentials (VP EPSPs). Possible explanations of these seemingly paradoxical findings are discussed, with arguments in favor and against each.

LSD's effect on neuron populations in visual cortex gauged by transient responses of extracellular potassium evoked by optical stimuli

The effects of systemic LSD (10--25 micrograms/kg) on visually evoked [K+]o responses from the striate cortex have been investigated in cats. Elevation of [K+]o was dependent on the orientation, and direction of stimulus movement and showed ocular dominance. LSD most commonly produced a depression of [K+]o transients and a deterioration in their directional selectivity. These observations suggest that the effect of LSD is to produce a net depression in visually evoked neuronal firing.