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At least 307 records · Page 17Linked to original sources
PubMed2002

Diurnal variation of dimethylallyl diphosphate concentrations in oak (Quercus robur) leaves.

In the present work a rapid and sensitive non-radioactive assay for the determination of cellular dimethylallyl diphosphate (DMADP) was developed and used for the analysis of the diurnal variation of DMADP levels in oak leaves. The method is based on the acid-catalysed hydrolysis of DMADP to isoprene, which subsequently is determined by gas chromatography. Diurnal variation of cellular DMADP levels in oak leaves of young saplings was measured on 6 days in 1998 and 1999, showing a 2 to 3-fold light-dependent increase from approximately 15 pmol mg-1 DW in the night to 31-75 pmol mg-1 DW around noon. The leaf DMADP contents showed a significant positive correlation with net assimilation and isoprene emission rates, indicating that the availability of cellular DMADP might be an important regulatory factor of leaf isoprene emission.

Journal Article↗
PubMed1999

Comparative study of genetic variation and differentiation of two pedunculate oak (Quercus robur) stands using microsatellite and allozyme loci

In a comparative study four codominant microsatellite loci and seven allozyme gene loci have been used to investigate the genetic variation and differentiation of two pedunculate oak stands in North Germany. Both number and effective number of alleles were five to six times higher and the observed heterozygosity was three times higher for the microsatellite than for the allozyme loci. One stand showed an overall excess of homozygotes. In general the microsatellites were closer to Hardy-Weinberg expectation. The genetic distances between the two stands were distinctly higher for microsatellites. For most parameters microsatellites exhibited smaller interlocus variation than the allozymes. The different impact of population genetic processes on the genetic structure as assessed by microsatellites or allozymes is discussed.

Journal Article↗
PubMed1993

Carbon and nitrogen assimilation in red oaks (Quercus rubra L.) subject to defoliation and nitrogen stress.

To examine how rates of net photosynthesis and N uptake of red oak seedlings respond to defoliation under contrasting conditions of N availability, nitrogen-deficient plants were grown in sand culture and subjected to partial defoliation and increased N availability under low light conditions. Both photosynthesis and N uptake rates were measured regularly before and after the treatments. Defoliation resulted in elevated rates of net photosynthesis in both low-N and high-N trees, but the high-N trees were able to maintain the high photosynthetic rates for a longer period of time. Nitrogen availability did not affect the photosynthetic rate of the undefoliated plants. Nitrogen uptake was not affected by the defoliation treatment, but was increased by increasing N availability in both the defoliated and undefoliated plants. Nitrogen uptake rates increased less than would be expected on the basis of N availability alone, but the uptake rates were apparently not limited by carbon supply in the short term. Suboptimal concentrations of N in plant tissues resulted in a strong sink for N even in the absence of refoliation.

Journal Article↗
PubMedDate not supplied

[Therapeutic effects of Quercus extract in urolithiasis].

97 patients suffering from urolithiasis were treated with Litiax. 82 of them presented ureteral stones and the other 15 kidney stones. The product was administered in doses of 1350 mg. a day. The treatment lasted between 8 and 225 days, the average duration being 58 days. It was revealed from the results obtained that the product tested has an inhibiting effect on the growth of the stone, antiinflammatory and diuretic. It also seems to inhibit the bacteria proliferation to a certain extent. The excellent tolerance of the product is stressed.

Adolescent↗
PubMed1982

Oak (Quercus rubor)poisoning in cattle.

Two outbreaks of oak poisoning in cattle in the Republic of South Africa are described. In the first outbreak 22 out of 80 head of cattle were severely affected while 40 out of a herd of 135 cattle were affected in the second outbreak. Of these 40, only one survived after 9 months despite vigorous treatment. Only young cattle under 2 years were affected during both outbreaks in spite of an average herd age of approximately 6 years in the second group of cattle. Clinical signs included severe weakness with a swaying gait, diarrhoea and dehydration. Some were pot bellied while others were emaciated and remained stunted. The most prominent macroscopic and microscopic lesion present in 3 animals autopsied, was a non-suppurative interstitial nephritis which was accompanied by oedema and ulceration of the caecum and colon. Histochemical studies were carried out on pigment granules observed in kidney sections.

Animals↗
PubMedDate not supplied

[Seasonal dynamics of the content of proteins inhibiting trypsin-like proteases in the leaves of common oak (Quercus petraea Liebl.)].

After the successive purification of proteins-inhibitors of trypsin-like proteases using the methods of chromatography on DEAE-cellulose, trypsin-agarose and sephadex G-50, their numerous forms with the values of molecular weight 3.5; 6.3; 12.5; and 25.0 kDa have been found out. From spring to autumn the increase of the absolute content of proteins-inhibitors of all types was accompanied by the change of their relative content. The more than by an order increase of general content of proteins inhibitors is discussed from the position of their stress origin as a result of the effect of unfavorable ecological factors.

Molecular Weight↗