Hyperacetylation of histone H4 promotes chromatin decondensation prior to histone replacement by protamines during spermatogenesis in rainbow trout

During the final stages of spermatogenesis in rainbow trout a dramatic increase in the level of histone H4 hyperacetylation is observed which is closely correlated with the replacement of histones by protamines. In order to understand further how H4 hyperacetylation might assist in protamine replacement of the histones, we have investigated the effect of H4 hyperacetylation on chromatin structure in trout testes actively undergoing the replacement process. Long chromatin fragments enriched in hyperacetylated H4 have been isolated and characterized. Evidence is presented that hyperacetylated H4 is clustered in certain regions (domains) of late stage testis chromatin and within these domains the chromatin exhibits an altered, highly relaxed structure which is believed to be the result of the extensive hyperacetylation. These domains, which are nearly devoid of protamine, are postulated to represent an initial structural transition which is necessary for the proper histone removal and protamine replacement process to take place.     

Anencephaly in trisomy 18 associated with elevated alpha-1-fetoprotein in amniotic fluid

Summary Elevated levels of alpha-1-fetoprotein (AFP) were found in the amniotic fluid of a 36-year-old woman in the 15th week of gestation. Because of this and the results of repeated ultrasonography, abortion was induced. An anencephalic fetus with trisomy 18 was delivered. The possible correlation among neural-tube defects, chromosomal abnormalities, and level of AFP is discussed.     

2-β-d-Glucopyranosyloxy-2-methylpropanol in Acacia sieberana var. woodii

A new diol glucoside, 2-β-d-glucopyranosyloxy-2-methylpropanol, the first reported naturally occurring monoglucoside of an aliphatic dihydric alcohol, was isolated from pods of Acacia sieberana var. woodii. Structure elucidation was based on ¹ H and ¹³C NMR spectroscopy, and enzymatic analyses. The compound was hydrolysed very slowly by almond β-glucosidase, but cleaved by a β-glucuronidase enzyme complex from Helix pomatia.     

Schistosoma mansoni and Fasciola hepatica: Cross-resistance in mice with single-sex schistosome infections

Primary Schistosoma mansoni single-sex infections in mice, i.e., either male only or female only, did not stimulate any detectable level of heterologous resistance to challenge with Fasciola hepatica after 22 to 76 days, while statistically significant resistance to a challenge with F. hepatica was demonstrated in the presence of patent mixed-sex S. mansoni infections. Simultaneous infections with S. mansoni and F. hepatica induced a statistically significant reduction in the number of schisto-some worms established, i.e., the burden being reduced by 40.1 and 43.9%, respectively. There was no reduction of the F. hepatica worm burden. Similar features could be observed with a time interval of 48 hr between the S. mansoni infection and the F. hepatica challenge, i.e., the schistosome burden being reduced by 34.2 and 45.6%, respectively. Furthermore, simultaneous infections with S. mansoni and F. hepatica induced a statistically significant reduction of the egg production capacity per paired female schistosome worm as compared with that of the S. mansoni control group. Tissue egg counts of the various intestinal sections were reduced by 92.8–99.6%.     

Interaction between prostaglandins of the E-type with a urinary component from halothane anaesthetized rats

Prostaglandins of the E-type (PGE's) were found to react or combine with a urinary metabolite of Halothane yielding products which left unrecovered during the purification procedure preceeding specific radioimmunoassay of PGE₂. The products were retained on sephadex LH-20 columns, and showed on thin layer silica gel plates (TLC) R_f values lower than those of the parent PGE-compounds. The product formation is supposed to involve the β-hydroxyketone system of PGE, since PG's of the F and A type were unaffected. The product formation could be avoided by inducing anaesthesia with Hexobarbitone and maintaining the anaesthesia with Halothane-nitrous oxide or it could be reveresed by adding barbiturates to urine samples obtained from animals anaesthetized with Halothane- nitroux oxide alone. The barbiturates effectively competed with PGE for the metabolite leaving PGE to behave normally on sephadex LH-20 and TLC, thus enabling us to evaluate correctly the PGE₂ content by RIA.     

Hyperparathyroidism in pregnancy: case report and review of the literature.

The apparent incidence of hyperparathyroidism (HPT) is low in pregnancy but will likely increase now that more asymptomatic HPT is being diagnosed. However, since the serum calcium levels are decreased in pregnant women, mild primary HPT may go unrecognized. In untreated cases of HPT, complications during pregnancy or during the neonatal period have included spontaneous abortion, stillbirth, neonatal death, neonatal tetany and hypercalcemia. A review of the literature indicates a substantial improvement in fetal outcome when parathyroidectomy is done during pregnancy, as in the case reported here. Therefore, parathyroidectomy is the treatment of choice when the diagnosis is made during pregnancy, although oral phosphate therapy may be an alternative if surgery is contraindicated.     

A biometric study of some hybridizing Crataegus populations in Denmark

Crataegus curvisepala Lindm., C. laevigata (Poiret) DC. and C. monogyna Jacq. (Rosaceae) form hybrid complexes in Denmark due to introgression. C. palmstruchii Lindm. seems to be variously introgressed individuals of C. laevigata. C. eremitagensis Raunk., C. raavadensis Raunk. and C. schumacheri Raunk. apparently belong to C. curvisepala x laevigata. The delimitation between C. curvisepala x laevigata and C. laevigata x monogyna is discussed.     

Standardization of high-resolution flow cytometric DNA analysis by the simultaneous use of chicken and trout red blood cells as internal reference standards

Determination of nuclear DNA content by flow cytometry requires comparison with a reference standard. The use of external standards such as lymphocytes or granulocytes is time-consuming and inaccurate. Chicken red blood cells (CRBC) have a DNA content of 35% of the human diploid value and have been widely used as internal standard. The ratio calculated on the basis of the peak channel numbers of the standard and the sample and used to indicate the DNA content (DNA ratio) is, however, very sensitive to changes in the zero level adjustment of the flow cytometer. If two internal standards are used the DNA ratio becomes independent of the zero level. Rainbow trout red blood cells (TRBC) have a DNA content of 80% of human diploid cells. A mixture of CRBC and TRBC was prepared and stored in small aliquots at -80 degrees C. This mixture was added to the sample before staining. The day-to-day variation of the DNA ratio obtained by use of the two standards was smaller than that obtained by CRBC alone. The possibility of sex related differences in DNA content of CRBC and TRBC was examined. The results indicated that a new batch of standards should be tested against the old batch to avoid the introduction of a systematic error.     

Effect of the organophosphorous insecticide, chlorpyrifos (Dursban), on growth, fecundity and mortality of Biomphalaria alexandrina and on the production of Schistosoma mansoni cercariae in the snail.

Exposure of Biomphalaria alexandrina to sublethal concentrations (0.125, 0.25 and 0.05 ppm) of the organophosphorous insecticide, chlorpyrifos (Dursban), induced a reduction in egg production and egg hatchability. Exposure of Schistosoma mansoni miracidia to the insecticide (60 min, 0.50 ppm) prior to infection of B. alexandrina did not affect the subsequent production of cercariae. However, exposure of S. mansoni-infected snails to the insecticide until day 55, from day 20 to day 62 and from day 35 to 62 following infection resulted in blockage of cercarial shedding. Cercarial shedding commenced in some snails when the treatment stopped. Exposure to the insecticide in concentrations of 0.125 and 0.25 ppm during the first 20 days following infection did not affect the subsequent production of cercariae, but exposure to 0.5 ppm during the first 20 days affected markedly the production of cercariae due to a high snail mortality. The findings indicate that the cercaria is the target stage for the activity of chlorpyrifos on the intramolluscan larval development. It is suggested that S. mansoni cercarial production in B. alexandrina may be a useful system for monitoring the effect of low concentrations of pesticides on the aquatic environment, and that the ability by chemical means to interrupt the cercarial production might be a useful tool in further analyses of important aspects of the snail/parasite relationship.