Plant diversity in late medieval cornfields of northern Switzerland

Weed assemblages from late medieval cornfields have been studied for the first time in northern Switzerland. Eleven samples from at least two different grain stores were investigated. The samples were collected from the carbonised remains of six wooden houses built in the late 13th century A.D. and which burnt down in the middle of the 15th century. The weed floras found in the spelt (Triticum spelta) and oats (Avena sativa) indicate a high botanical diversity in the cornfields at harvest time. Although oats are normally a summer crop and spelt a winter crop, both summer and winter crop weeds (as well as many different present-day grassland taxa) were found in each type of grain. Most of the weeds found were perennial plants, which was interpreted as an indication of both extensive tillage of the arable land and application of the three-field rotation system (Dreifelderwirtschaft). The spectra of the two palaeophytocoenoses (assemblages of ancient plant remains) studied suggest that the phytosociological method may not be reliable for classification of the late medieval remains into summer and winter crop weed communities. These findings should provide a better understanding of the development of anthropogenic plant communities, and in particular, the development of crop weed communities.     

Developmental regulation of presence of binding sites for neoglycoproteins and endogenous lectins in various embryonic stages of human lung,liver and heart

Protein-carbohydrate interactions are supposed to play key roles in the mechanisms of cell adhesion, biosignalling and intracellular routing, warranting the analysis of the developmental course of expression of epitopes of this system. Thus, a panel of carrier-immobilized carbohydrate ligands was used as probes, namely lactose,N-acetylgalactosamine,N-acetylglucosamine, mannose, fucose and maltose. Additionally, an antibody to an endogenous -galactoside-binding lectin (anti-galectin-1), the biotinylated lectin and two further human lectins, namely the macrophage migration inhibitory factor-binding sarcolectin and serum amyloid P component (SAP) that displays selectivity for sulphated sugars and mannose-6-phosphate, were included. They enabled us to assess the extent of the presence of respective binding sites in fixed sections from human lungs (pulmonary epithelial cells), livers (hepatocytes) and hearts (myocard cells) of 10–50 weeks gestation. Invariably, specific binding was detected in the three organ types, at least in certain stages. In most of the cases, the intensity of staining exhibited developmental regulation. The apparent patterns reveal similarities between the different cell types, as seen with immobilizedN-acetylglucosamine as well as with labelled galectin-1 and sarcolectin. However, drastic differences among such patterns with nearly opposite developmental courses do also occur, as detected for carrier-attached mannose and maltose residues. These results point to a potential importance for the detected glycohistochemical features in human development and substantiate the possibility of differential regulation of the presence of binding sites for distinct sugars within a certain organ and between the individual cell types of the monitored organs.     

A new Dol-P-Man:protein O-D-mannosyltransferase activity from Saccharomyces cerevisiae

The deletion of the protein mannosyltransferase 1 gene (PMT1)of Saccharomyces cerevisiae results in viable cells. O-Mannosylationof proteins is reduced to about half of the value in comparisonto wild-type cells. In order to distinguish between the thePMT1 gene product (= Pmt1p) and residual transferase activity,an in vitro assay to measure Dol-P-Man:protein mannosyltransferaseactivity in cells deleted for PMT1 has been developed. The transferaseactivity of these cells exhibits a pH optimum of 6.5 as comparedto pH 7.5 for Pmt1p. The K_$$$ value of the residual enzyme activityfor the hexapeptide YNPTSV is 7 times higher than that of Pmt1pand shows a clear preference for the seryl/residue. Differencesin substrate affinities as well as in seryl/threonyl preferencebetween the two enzymes, however, depend on the specific sequenceof the peptides used in the enzyme assay. The new enzyme activityshows a significantly lower thermal stability as compared toPmt1p. glycoprotein O-glycosylation mannosyltranferase Saccharomyces cerevisiae     

Age-related changes in responsiveness of rat Leydig cells to hCG

The responsiveness of decapsulated testes and isolated Leydig cell preparations from rats (30-80 days of age) to a constant dose of 3 ng hCG/2 ml was assessed by comparison of the production of testosterone and "total 17beta-hydroxy androgen" (17beta-HA). When testosterone secretion was used as the index of response, there was a marked increase in the production with age by decapsulated testes and also by equal numbers of Leydig cells. When 17beta-HA was taken as the response parameter this increase was only marginal for the decapsulated testes and there was an age-dependent decrease when expressed per 10(6) cells. These differences probably reflect changes in the metabolism of testosterone to 5alpha-reduced products with increasing age because 80% of androgen secreted at 30 days is 3alpha-androstanediol and 86% is secreted as testosterone at 80 days. We conclude that for studies on hCG responsiveness and the steroidogenic capacity of immature rat Leydig cells (a) testosterone is an inappropriate response parameter and (b) this response undergoes a decrease rather than an increase during prepubertal development.     

Preincubation stimulates fatty acid synthesis by liver slices and isolated hypatocytes from fasted and diabetic rats.

We have observed that preincubation of 48 hour-fasted or alloxan diabetic rat liver slices, with no exogenous energy supply, for 3 hours resulted in an increased rate of incorporation of [1-¹⁴C] acetate into fatty acids and cholesterol during the following 2 hours. This preincubation effect was enhanced by the presence of glucose (25mM) in or prevented by the addition of dibutyryl cyclic adenosine 3′,5′ monophosphate (10^?4M) to the preincubation medium. Preincubation of normal rat liver slices did not change their rate of incorporation of [1-¹⁴C] acetate into fatty acids or cholesterol. The rate of ¹⁴CO₂ synthesized by normal, fasted or diabetic liver slices was little affected by preincubation. The preincubation effect, i.e. enhanced fatty acid synthesis was also observed in suspensions of hepatocytes from fasted and diabetic rats, preincubated for 2 hours, followed by a 1 hour incubation with either [1-¹⁴C] acetate or [³H] H₂O as precursor. We conclude from these data that there is concurrent and coordinated short- and long-term regulation of fatty acid biosynthesis in fasted and diabetic rat livers. Further, we suggest that the release of inhibition by preincubation of these tissues provides a useful tool for studying the coordinated control     

Activities in vitro and in vivo of enzymes of benzodiazepine alkaloid biosynthesis during development of Penicillium cyclopium

In the hyphae of Penicillium cyclopium the in vitro measurable activities of 3 enzymes of alkaloid biosynthesis are induced endogenously during     

Effects of bleomycin on the epidermal content of growth-regulatory substances (chalones).

Hairless male mice were given 2 mg Bleomycin i.p. on two successive days. At different time intervals from 1 to 10 days after the last Bleomycin injection, groups of animals were killed and water extracts of hemogenized skin were made. These extracts, supposed to contain the epidermal G1 and G2 chalones, were injected into female hairless mice, and their growth inhibitory potency determined by two methods. 5 mg of lyophilized crude skin extract were injected i.p. together with Colcemid, and the animals killed 4 hr later. The number of Colcemid-arrested mitoses was determined, and was considered to be a measure of the G2 inhibitor present in the skin extracts. 10 mg of the same extracts were injected i.p., and these animals also got 3H-TdR i.p. 12 hr later, and were killed after a subsequent 30 min. The epidermal LI was determined, and was considered to be a measure of the epidermal G1 factor in the skin extracts. The results obtained were compared to the effect of Bleomycin alone and to the effects of skin extracts from non-Bleomycin-treated animals. The results show that Bleomycin provoked slight alterations in the growth-inhibitory potency of the G1 chalone, whereas significant effects were seen in the G2 chalone, There was an increased amount of growth-inhibiting factors on days 2 and 3, and on days 8-10. The results are discussed and it is concluded that the most probable hypothesis is that Bleomycin, in addition to its known inhibition by accumulation of cells with high growth inhibitory potency. An initial, additional direct effect of Bleomycin on the chalone system cammot be excluded.