The genetic mating system and tests for cuckoldry in a pipefish species in which males fertilize eggs and brood offspring externally.

Highly variable microsatellite loci were used to study the mating system of Nerophis ophidion, a species of pipefish in which pregnant males carry embryos on the outside of their body rather than in an enclosed brood pouch. Despite this mode of external fertilization and brooding, otherwise rare in the family Syngnathidae, the genotypes of all embryos proved to be consistent with paternity by the tending male, thus indicating that cuckoldry by sneaker males is rare or nonexistent in this species. N. ophidion is a phylogenetic outlier within the Syngnathidae and its reproductive morphology is thought to be close to the presumed ancestral condition for pipefishes and seahorses. Thus, our genetic results suggest that the evolutionary elaboration of the enclosed brood pouch elsewhere in the family was probably not in response to selection pressures on pregnant males to avoid fertilization thievery. With regard to maternity assignments, our genotypic data are consistent with behavioural observations indicating that females sometimes mate with more than one male during a breeding episode, and that each male carries eggs from a single female. Thus, the polyandrous genetic mating system in this species parallels the social mating system, and both are consistent with a more intense sexual selection operating on females, and the elaboration of secondary sexual characters in that gender.

3-Hydroxy-3-methylglutaryl-coenzyme A lyase deficiency: report of five new patients.

Five new patients are reported and the pathogenesis of the hypoglycaemia without ketogenesis is discussed. This report extends a recent review.

Participation of voltage-dependent calcium channels in the action of gonadotropin-releasing hormone.

The roles of calcium ions and voltage-sensitive calcium channels in gonadotropin-releasing hormone (GnRH)-stimulated luteinizing hormone (LH) release were investigated in rat anterior pituitary cells. The calcium ionophores A23187 and ionomycin stimulated LH release from cultured pituitary cells, in which ionomycin (5 X 10(-5) M) was as effective as a maximal concentration of GnRH (10(-8) M). In addition, a concentration of the calcium channel agonist methyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyridine- 5-carboxylate (BK 8644) (10(-8) M), which did not alter basal LH release, potentiated the ability of submaximal (10(-10) and 10(-9) M) doses of GnRH to increase LH secretion. Furthermore, concentrations of the calcium channel antagonist nitrendipine (10(-8)-10(-5) M) that did not alter basal LH release, inhibited GnRH-stimulated LH secretion by 30-40%. Nitrendipine (10(-8) M) also blocked the potentiation of GnRH-induced LH secretion by BK 8644. During column perifusion of pituitary cells, 10(-8) M nitrendipine reduced the LH response to a 2-min pulse of 10(-8) M GnRH by about 40%. In Quin-2-loaded pituitary cells, supramaximal doses (10(-6) M) of a potent GnRH agonist rapidly elevated cytoplasmic Ca2+ by 50-100 nM. Concomitant treatment with nitrendipine decreased the GnRH agonist-induced Ca2+ signal by 40-60%. These results indicate that increases in intracellular Ca2+ via voltage-sensitive calcium channels partially reproduce GnRH action, and also that GnRH causes activation of such channels. However, the increase in cytoplasmic Ca2+ concentration during GnRH action must originate in part from mobilization of internal Ca2+ stores, and its relatively small magnitude may be consistent with the concomitant activation of protein kinase C as an intermediate step in GnRH action.

Decreased calcium content and 45Ca2+ uptake in Down's syndrome blood platelets.

Total intracellular Ca2+ and 45Ca2+ uptake has been studied in blood platelets from subjects with Down's syndrome and matched controls. In Down's subjects, Ca2+ levels (85.5 +/- 5.9 nmol/10(-9) platelets) were significantly lower than controls, 174 +/- 10.0 nmol/10(-9) (p less than 0.0005). A similar reduction was seen in calcium uptake (Down's platelets, 0.79 +/- 0.06 nmol/10(-9) platelets; controls, 1.17 +/- 0.07 nmol/10(-9) platelets, p less than 0.005). The low levels of intracellular Ca2+ may be related to decreased granular storage of serotonin, and the decreased Ca2+ uptake with impaired transport by intracellular Ca2+-accumulating organelles such as the dense tubular system.

Decreased polyamine content of concanavalin a stimulated lymphocytes in Down's syndrome subjects.

Increased polyamine content is associated with increased rates of cell growth. Several Down's syndrome (D.S.) tissues have been shown to have decreased growth rates. Studies were undertaken to determine if the polyamine content of stimulated D.S. lymphocytes was similar to that of stimulated normal cells. Lymphocytes were isolated and cultured in the presence of Concanavalin A for 4 or 5 days. Polyamines were than extracted and quantitated. After 4 days spermidine content for normal cells was 930.9 +/- 127 and for D.S. cells 489.2 +/- 113.1 nmoles/10(9) cells (P less than 0.025). Spermine content of normal cells was 1152.8 +/- 157.4 and for D.S. cells 533.9 +/- 82.0 (P less than 0.005). After 5 days in culture spermidine content of normal cells was 803.0 +/- 75.9 and for D.S. cells 446.2 +/- 76.5 nmoles/10(9) cells (P less than 0.005). Spermine content was 1155.7 +/- 121.9 for normal cells and 555.1 +/- 68.4 nmoles/10(9) for D.S. cells. Decreased content of polyamines in D.S.-stimulated lymphocytes is most probably due to decreased rate of polyamine synthesis. Decreased content of polyamines in response to stimulation may be a factor in decreased growth rates and altered immune function seen in D.S. patients.

Hypohidrotic ectodermal dysplasia with hypothyroidism.

Two brothers with hypohidrotic ectodermal dysplasia were found to have urticaria pigmentosa-like skin pigmentation with increased mast cells and melanin depositions in the dermis. Structural ciliary abnormalities of the respiratory tract were seen, and these may contribute to their severe recurrent chest infections. Primary hypothyroidism occurred in both by 3 years of age and responded to replacement therapy. The abnormalities seen appear to be the result of a common genetic aberration causing a particular sequence of maldevelopments during embryogenesis. This form of hypohidrotic ectodermal dysplasia associated with hypothyroidism gives a unique insight into the potential extent of structural defects of ectodermal dysplasias.

A study of gamma-aminobutyric acid uptake in normal and Down's syndrome platelets.

1. Initial uptake rates of gamma-aminobutyric acid (GABA) were compared in Down's syndrome (D.S.) and normal platelets GABA uptake was decreased in D.S. platelets (1.10 +/- 0.10 nmol h-1 10(-9)) compared to uptake by normal platelets (1.89 +/- 0.21 nmol h-1 10(-9), P less than 0.005. 2. The effect of varying the NA+ concentration was similar on D.S. and normal platelets. Increasing the media Na+ concentration resulted in increased rates of GABA uptake in both D.S. and normal platelets. 3. GABA uptake in the presence of 2,4-dinitrophenol or at 2 degrees C is approximately 56% of the uptake at 37 degrees C for both D.S. and normal platelets. 4. Extrapolation of a reciprocal plot indicates a two affinity uptake system; a high affinity and a low affinity mechanism. 5. A significant defect in GABA uptake exists in D.S. platelets.

Phospholipid composition of Down's syndrome and normal platelets.

1. Total and individual phospholipids were quantitated in platelets isolated from normal and Down's syndrome (D.S.) subjects. Phospholipids were extracted from isolated platelets, separated by thin layer chromatography and quantitated by measurement of fluorescence of the compounds using a thin layer chromatogram scanner. The total amount of phospholipid was similar in D.S. and control subjects. The amount and percent composition of phosphatidyl serine, phosphatidyl ethanolamine, phosphatidgl inositol, phosphatidyl choline and sphingomyelin was also similar in D.S. and normal platelets. 2. The studies were undertaken to determine if the decrease in Na+/K+ AtPase activity observed in D.S. platelets was associated with alteration in phospholipid composition. The present report would indicate that no major differences in phospholipid composition are present in D.S. platelets that would account for the observed decrease in Na+/K+ AtPase activity.

Factors affecting inosinate synthesis and inosine triphosphate accumulation in human erythrocytes.

Measurements of rates of inosinate synthesis from radioactive hypoxanthine by human erythrocytes show a large degree of individual variation. Rates of inosinate synthesis also vary with the pH and phosphate concentration of the incubation medium. This may be due to changes in the rate of phosphoribosyl pyrophosphate synthesis, and the stimulatory effect of phosphate on this process seems to be more important than the inhibitory effect of 2,3-diphodphoglycerate. The rate of inosinate synthesis, and especially the extent of accumulation of inosine triphosphate, increase disproportionately with time of incubation up to at least 24 h. Storage of erythrocytes also tends to increase inosinate synthesis and inosine triphosphate accumulation.

Relationships between nucleoside triphosphate pyrophosphohydrolase activity and inosine triphosphate accumulation in human erythrocytes.

The relationship between nucleoside triphosphate pyrophosphohydrolast (NTPH) (EC 3.6.1.19) activity in erythrocyte lysates and accumulation of radioactive inosine triphosphate (ITP) in human erythrocytes incubated in vitro with [14C]hypoxanthine, was studied in 93 humans. When ITP accumulation, expressed as percentage of total radioactive nucleotides, was plotted against NTPH specific activity, an inverse relationship was found to exist. A continous spectrum of NTPH specific activities and ITP accumulation values exists in the human population and the relationship between these two parameters follows the relationship of substrate concentration to enzyme activity predicted by Michaelis-Menten enzyme kinetics. One interpretation of these data is that the ITP concentration in human red blood cells is controlled by the degradation of ITP to IMP and pyrophosphate catalyzed by NTPH.

Individual variation in inosine triphosphate accumulation in human erythrocytes.

Erythrocytes from 5% of a normal population accumulated relatively high amounts of radioactive inosine triphosphate (i.e., greater than 70 nmoles/10(10) cells in 2 hr) when they were incubated with [14C]hypoxanthine. The incidence of this characteristic in a mentally retarded population was 16%. Inosine triphosphate was synthesized from [14C]hypoxanthine, but not from [14C]adenine or [14C]guanine. The metabolism of [14C]adenine and [14C]guanine was the same in erythrocytes that accumulated "normal" and "high" amounts of inosine triphosphate. Inosine triphosphate did not accumulate in leukocytes.

HL-A frequencies in Down's syndrome.

HL-A antigen frequencies were examined in 76 Down's syndrome individuals and 733 normal Caucasians. 10 antigens of the first locus and 15 antigens of the second locus were defined, using a microlymphocytotoxicity technique. No significant differences were observed between the normal and Down's syndrome samples, in contrast to a previous report (Boxer and Yokoyama, 1972) of decreased HL-A antigen frequencies in Down's syndrome individuals. Our results therefore suggest that there is no relationship between trisomy 21-associated immune aberrations and altered HL-A antigen frequencies.