New insights into vegetation dynamics and settlement history in Hümmling,north-western Germany,with particular reference to the Neolithic

Palynological investigations on two well-dated peat profiles provide insights into Neolithic vegetation and settlement history from Hümmling in north-western Germany. The site selections allow comparisons between local and regional vegetation changes and are used to estimate the extent of Neolithic influence on the vegetation. The interpretation of the fossil spectra relied on radiocarbon dating, evaluation of pollen indicator taxa, non-pollen palynomorphs and multivariate techniques. During the late Mesolithic the vegetation was dominated by mixed oak forests while openings in forest cover were detected, with a decline in elm reflected in the regional pollen record around 4250 cal. b.c. The presence of humans is shown by settlement indicators that are first recorded at ca. 3800 cal. b.c. Vegetation changes were small between 4300 and 3600 cal. b.c. This suggests that regional vegetation was relatively resilient to small-scale disturbances. Possible indications of grazing were recorded in the spectra of the local pollen profile but there is no clear-cut evidence for Neolithic activity. Between 3520 and 2260 cal. b.c. decreases in forest cover were inferred from both profiles and increases in settlement indicators reflect farming activity. These changes coincide with the emergence in the area of the Funnel Beaker Culture and the subsequent Single Grave Culture. Both profiles suggest that settlement probably ceased between ca. 3230 and 3050 cal. b.c. This lull or cessation in activity was probably regional in character. After 2260 cal. b.c. human impact on the vegetation decreases and woodlands regenerate. The longevity of the regeneration phase—ca. 690 years—was probably connected with the low resilient capability of the vegetation on the poor soils.     

Wood use in a medieval village: the contribution of wood charcoal analysis to the history of land use during the 13th and 14th centuries a.d. at Pobla d’Ifach, Calp, Alicante, Spain

Excavations on the Rock of Ifach, Alicante, Spain have revealed the remains of a medieval settlement that flourished between a.d. 1297 and 1359. Wood charcoal analysis combined with archaeological evidence and historical records allow an assessment of the local vegetation of the area during the medieval period, the obtaining and use of firewood and the commercial routes for supplying timber. Pinus halepensis and to a lesser degree various matorral taxa were used for fuel during the main occupation phases at the settlement. The resource exploitation network of the settlement expanded over the adjacent coastal area, with firewood obtained from pine woodlands there. The timbers used in the construction of the settlement were mainly from pines that originated nearby (P. halepensis) or which were transported by river from woodland areas to the north which were controlled by the Crown of Aragon (P. nigra/sylvestris, P. pinaster). The partial destruction of the village in a.d. 1359 and its gradual abandonment are reflected in changes observed in fuel supplying practices that then concentrated on the local matorral vegetation of the rock itself.     

Holocene anthropogenic landscapes in the Balkans: the palaeobotanical evidence from southwestern Bulgaria

Palaeoecological reconstructions from the region of southwestern Bulgaria were used for inferring the human impact on the vegetation and landscape during the last 8 millennia. They are based on data from pollen analyses of lakes and peat-bogs, plant macrofossils, archaeobotanical finds and radiocarbon dating. During the early Holocene, after 7900?cal. b.p. (5950?cal. b.c.) the climate changed to cooler summers, milder winters and higher precipitation resulting in the formation of a coniferous belt dominated by Pinus sp. and Abies alba. These favorable environmental pre-conditions had a positive influence on the Neolithisation of the Balkans after the 8200?cal. b.p. (6250?cal. b.c.) cold event, which caused drought in the Eastern Mediterranean. Direct evidence from wood charcoal records from the Neolithic settlement layers in the study area shows a slight modification of the surrounding woodlands and an increase of the light-demanding components, probably expressed through larger forest border zones and thinning out of the wood stands. The increase in the number of settlements in the valleys of southwestern Bulgaria intensified the human activity visible in the palaeobotanical record from 6950?cal. b.p. (5000?cal. b.c.) onwards. Between ca. 5700–5100?cal. b.p. (3800–3200?cal. b.c.) signs of anthropogenic influence on the vegetation are virtually absent. The intensity of human impact increased notably after 3200?cal. b.p. (1400–1250?cal. b.c., approx. Late Bronze Age), documented by a rise of pollen anthropogenic indicators. The final transformations in the natural forest cover after 2750?cal. b.p. (800?cal. b.c. onset of the Iron Age) marked the reduction of the coniferous forests dominated by Abies alba and Pinus sp. and the expansion of Fagus sylvatica and Picea abies. These vegetation changes are contemporaneous with increase of the palaeofire activities and the next peak of anthropogenic indicators. The changes in the landscape during the Roman period and the medieval period reflect regional environmental features and were forced by the diversification of anthropogenic activity.     

Palaeoecological evidence for the middle and late Holocene vegetation, climate and land use in the upper Don River basin (Russia)

New pollen and plant macrofossil data, backed by radiocarbon dates, from the Kulikovo battlefield area in the forest-steppe region of the Upper Don River basin (central part of European Russia) indicate that the area was covered by mosaic vegetation in the second half of the Holocene. Steppe communities dominated during the mid—late Atlantic (7.2–5.7?cal.?kyr b.p.) and early Subatlantic (2.7–2.4?cal.?kyr b.p.), while forest-steppe dominated during the Subboreal (2.7–5.7?cal.?kyr b.p.), middle and late Subatlantic (2.4?cal.?kyr b.p. – present). Climatic reconstructions based on these data show that landscape dynamics in the region were most probably driven by changes in effective moisture: an excess of precipitation over evaporation. Even small reductions in annual precipitation, accompanied by a rise in summer temperatures by 1–3°C above present values, were sufficient to increase the proportion of steppe communities within this landscape complex, and also probably resulted in higher frequencies of wildfires. Signals of anthropogenic disturbance of vegetation are clearly pronounced in the pollen and plant macrofossil records since the middle Atlantic. However, human-induced changes in the vegetation remain subtle until the medieval period.     

d-Amino Acid-Induced Expression of d-Amino Acid Oxidase in the Yeast Schizosaccharomyces pombe

We investigated d-amino acid oxidase (DAO) induction in the popular model yeast Schizosaccharomyces pombe. The product of the putative DAO gene of the yeast expressed in E.?coli displayed oxidase activity to neutral and basic d-amino acids, but not to an l-amino acid or acidic d-amino acids, showing that the putative DAO gene encodes catalytically active DAO. DAO activity was weakly detected in yeast cells grown on a culture medium without d-amino acid, and was approximately doubled by adding d-alanine. The elimination of ammonium chloride from culture medium induced activity by up to eight-fold. l-Alanine also induced the activity, but only by about half of that induced by d-alanine. The induction by d-alanine reached a maximum level at 2?h cultivation; it remained roughly constant until cell growth reached a stationary phase. The best inducer was d-alanine, followed by d-proline and then d-serine. Not effective were N-carbamoyl-d,l-alanine (a better inducer of DAO than d-alanine in the yeast Trigonopsis variabilis), and both basic and acidic d-amino acids. These results showed that S. pombe DAO could be a suitable model for analyzing the regulation of DAO expression in eukaryotic organisms.     

A marine/terrestrial integration for mid-late Holocene vegetation history and the development of the cultural landscape in the Po valley as a result of human impact and climate change

Integration of pollen data from both marine and terrestrial cores contributes to the understanding of the timing of the climatic and human forces that shaped the cultural landscapes in the Italian peninsula. This paper focuses on the relation between natural and human landscapes, and the development of the cultural landscape from the Bronze Age to the medieval period and modern times. Two records were studied within independent projects, first the marine core RF93-30, from the central Adriatic, with a sediment source area including the Po valley and which spans the last 7,000?years, and secondly, material from the site of Terramara di Montale, a Bronze Age settlement on the Po plain, which was occupied from approximately 3550–3200?cal. b.p. The original chronology of the marine core was developed by using the magnetic inclination of the secular variation record and two ¹⁴C dates carried out on benthic and planktic foraminifera at depths of 527 and 599?cm. Its pollen record shows a gradual irreversible trend towards increasing aridity since 5700?cal. b.p. and, just after around 5100?cal. b.p., a Picea decline and a Quercus ilex type increase indicate less cool conditions. Human impact introduces rapid changes, such as the decrease of Abies alba, thinned by the reduction of precipitation and further cleared before or during the Early Bronze Age, followed by the fall of oaks. The latter started after around 3900?cal. b.p., and became evident at around 3600?cal. b.p. The gradual increase in signs of open landscape and woodland clearance correspond to the onset of Middle Bronze Age settlements in the Po valley, and to the development of the cultural landscape in the region. The impact of the terramare people includes woodland management by coppicing, and division of the territory into a patchwork of pastures and fields. Dry environments are indicated mainly by Cichorioideae, resulting from the continued human pressure, and these spread since the Recent Bronze Age. Of the possible causes for the decline of the terramare, we suggest that climate would have been less important in the decline than in the onset phases. The later cultural landscapes are mainly indicated by the trends of the Olea, Juglans and Castanea (OJC) records, besides those of cereals. At around 700?cal. b.p., the “chestnut landscape” spread while modern times are shown by the finds of Zea mays.     

The impact of prehistoric mining activities on the environment: a multidisciplinary study at the fen Schwarzenbergmoos (Brixlegg, Tyrol, Austria)

The exploitation of copper ore deposits of the northern Greywacke Zone was initiated by the implementation of metallurgic technologies in the Eastern Alps thousands of years ago. This multi-proxy study aimed to detect prehistoric mining phases in the vicinity of a prominent copper ore deposit in the Lower Inn Valley. Therefore we studied a peat core from a fen using pollen, micro charcoal and geochemical analyses. In the same fen, an archaeological investigation revealed an ore beneficiation site, well dated by dendrochronological analysis to the Late Bronze Age (9th century b.c.). First hints of mining activities reflected by the occurrence of anthropogenic indicators in the pollen diagram, associated with elevated metal values, at the beginning of the Bronze Age might result from early mineral prospecting and metallurgical experiments around the use of fahlore. The local ore deposit was then abandoned until during the Bronze Age mining activities started to increase. This is reflected by an expansion of the pioneer species Pinus and Larix on mine spoil heaps in the proximity. Concomitantly metal ratios and micro charcoal increase. From about 1000 to 850 b.c. a strong impact of mining activities is displayed in the multi-proxy data. The local forest was partly cleared on and in the vicinity of the fen. According to dendrochronological data the ore beneficiation plant was in use from about 900 to 870 b.c. Until about 700 b.c. another period with moderate impact by mining activities in the further vicinity of the fen shows up.     

Isomerization ofd-glycero-d-galacto-heptose tod-manno-heptulose by selected yeasts

Selected eight yeast strains isomerized-glycero-d-galacto-heptose tod-manno-heptulose. The conversion is 7–10%. Under identical conditions, the reverse isomerization ofd-manno-heptulose tod-glycero-d-galacto-heptose ord-glycero-d-talo-heptose does not take place.     

Backbone and side-chain 1H, 15N and 13C assignment of apo- and imipenem-acylated l,d-transpeptidase from Bacillus subtilis

The d,d-transpeptidase activity of Penicillin Binding Proteins (PBPs) is essential to maintain cell wall integrity. PBPs catalyze the final step of the peptidoglycan synthesis by forming 4 → 3 cross-links between two peptide stems. Recently, a novel β-lactam resistance mechanism involving l,d-transpeptidases has been identified in Enterococcus faecium and Mycobacterium tuberculosis. In this resistance pathway, the classical 4 → 3 cross-links are replaced by 3 → 3 cross-links, whose formation are catalyzed by the l,d-transpeptidases. To date, only one class of the entire β-lactam family, the carbapenems, is able to inhibit the l,d-transpeptidase activity. Nevertheless, the specificity of this inactivation is still not understood. Hence, the study of this new transpeptidase family is of considerable interest in order to understand the mechanism of the l,d-transpeptidases inhibition by carbapenems. In this context, we present herein the backbone and side-chain ¹H, ¹⁵N and ¹³C NMR assignment of the l,d-transpeptidase from Bacillus subtilis (Ldt_Bs) in the apo and in the acylated form with a carbapenem, the imipenem.     

Function of aspartic acid residues in optimum pH control of l-arabinose isomerase from Lactobacillus fermentum

l-Arabinose isomerase (l-AI) catalyzes the isomerization of l-arabinose to l-ribulose and d-galactose to d-tagatose. Most reported l-AIs exhibit neutral or alkaline optimum pH, which is less beneficial than acidophilic ones in industrial d-tagatose production. Lactobacillus fermentum l-AI (LFAI) is a thermostable enzyme that can achieve a high conversion rate for d-galactose isomerization. However, its biocatalytic activity at acidic conditions can still be further improved. In this study, we report the single- and multiple-site mutagenesis on LFAI targeting three aspartic acid residues (D268, D269, and D299). Some of the lysine mutants, especially D268K/D269K/D299K, exhibited significant optimum pH shifts (from 6.5 to 5.0) and enhancement of pH stability (half-life time increased from 30 to 62 h at pH 6.0), which are more favorable for industrial applications. With the addition of borate, d-galactose was isomerized into d-tagatose by D268K/D269K/D299K at pH 5.0, resulting in a high conversion rate of 62 %. Based on the obtained 3.2-Å crystal structure of LFAI, the three aspartic acid residues were found to be distant from the active site and possibly did not participate in substrate catalysis. However, they were proven to possess similar optimum pH control ability in other l-AI, such as that derived from Escherichia coli. This study sheds light on the essential residues of l-AIs that can be modified for desired optimum pH and better pH stability, which are useful in d-tagatose bioproduction.     

Detection of d-amino acids in purified proteins synthesized in Escherichia coli

It has long been believed that amino acids comprising proteins of all living organisms are only of the l-configuration, except for Gly. However, peptidyl d-amino acids were observed in hydrolysates of soluble high molecular weight fractions extracted from cells or tissues of various organisms. This strongly suggests that significant amounts of d-amino acids are naturally present in usual proteins. Thus we analyzed the d-amino acid contents of His-tag-purified β-galactosidase and human urocortin, which were synthesized by Escherichia coli grown in controlled synthetic media. After acidic hydrolysis for various times at 110°C, samples were derivatized with 4-fluoro-7-nitro-2, 1, 3-benzoxadiazole (NBD-F) and separated on a reverse-phase column followed by a chiral column into d- and l-enantiomers. The contents of d-enantiomers of Ala, Leu, Phe, Val, Asp, and Glu were determined by plotting index d/(d + l) against the incubation time for hydrolysis and extrapolating the linear regression line to 0 h to eliminate the effect of racemization of amino acids during the incubation. Significant contents of d-amino acids were reproducibly detected, the d-amino acid profile being specific to an individual protein. This finding indicated the likelihood that d-amino acids are in fact present in the purified proteins. On the other hand, the d-amino acid contents of proteins were hardly influenced by the addition of d- or l-amino acids to the cultivation medium, whereas intracellular free d-amino acids sensitively varied according to the extracellular conditions. The origin of these d-amino acids detected in proteins was discussed.     

d-Amino acids in the brain and mutant rodents lacking d-amino-acid oxidase activity

d-Amino acids are stereoisomers of l-amino acids. They are often called unnatural amino acids, but several d-amino acids have been found in mammalian brains. Among them, d-serine is abundant in the forebrain and functions as a co-agonist of NMDA receptors to enhance neurotransmission. d-Amino-acid oxidase (DAO), which degrades neutral and basic d-amino acids, is mainly present in the hindbrain. DAO catabolizes d-serine and, therefore, modulates neurotransmission. In the brains of mutant mice and rats lacking DAO activity, the amounts of d-serine and other d-amino acids are markedly increased. Mutant mice manifested behavioral changes characteristic of altered NMDA receptor activity, likely due to increased levels of d-serine. d-Serine and DAO have been demonstrated to play important roles in cerebellar development and synaptic plasticity. They have also implicated in amyotrophic lateral sclerosis and pain response. There have also been several lines of evidence correlating DAO with schizophrenia. Taken together, the experiments indicate that d-amino acids and DAO have pivotal functions in the central nervous system.     

Current knowledge of d-aspartate in glandular tissues

Free d-aspartate (d-Asp) occurs in substantial amounts in glandular tissues. This paper reviews the existing work on d-Asp in vertebrate exocrine and endocrine glands, with emphasis on functional roles. Endogenous d-Asp was detected in salivary glands. High d-Asp levels in the parotid gland during development suggest an involvement of the amino acid in the regulation of early developmental phases and/or differentiation processes. d-Asp has a prominent role in the Harderian gland, where it elicits exocrine secretion through activation of the ERK1/2 pathway. Interestingly, the increase in NOS activity associated with d-Asp administration in the Harderian gland suggests a potential capability of d-Asp to induce vasodilatation. In mammals, an increase in local concentrations of d-Asp facilitates the secretion of anterior pituitary hormones, i.e., PRL, LH and GH, whereas it inhibits the secretion of POMC/α-MSH from the intermediate pituitary and of oxytocin from the posterior pituitary. d-Asp also acts as a negative regulator for melatonin synthesis in the pineal gland. Further, d-Asp can stereo-specifically modulate the production of sex steroids, thus taking part in the endocrine control of reproductive activity. Although d-Asp receptors remain to be characterized, gene expression of NR1 and NR2 subunits of NMDAr responds to d-Asp in the testis.     

Alteration of intrinsic amounts of d-serine in the mice lacking serine racemase and d-amino acid oxidase

For elucidation of the regulation mechanisms of intrinsic amounts of d-serine (d-Ser) which modulates the neuro-transmission of N-methyl-d-aspartate receptors in the brain, mutant animals lacking serine racemase (SRR) and d-amino acid oxidase (DAO) were established, and the amounts of d-Ser in the tissues and physiological fluids were determined. d-Ser amounts in the frontal brain areas were drastically decreased followed by reduced SRR activity. On the other hand, a moderate but significant decrease in d-Ser amounts was observed in the cerebellum and spinal cord of SRR knock-out (SRR^?/?) mice compared with those of control mice, although the amounts of d-Ser in these tissues were low. The amounts of d-Ser in the brain and serum were not altered with aging. To clarify the uptake of exogenous d-Ser into the brain tissues, we have determined the d-Ser of SRR^?/? mice after oral administration of d-Ser for the first time, and a drastic increase in d-Ser amounts in all the tested tissues was observed. Because both DAO and SRR are present in some brain areas, we have established the double mutant mice lacking SRR and DAO for the first time, and the contribution of both enzymes to the intrinsic d-Ser amounts was investigated. In the frontal brain, most of the intrinsic d-Ser was biosynthesized by SRR. On the other hand, half of the d-Ser present in the hindbrain was derived from the biosynthesis by SRR. These results indicate that the regulation of intrinsic d-Ser amounts is different depending on the tissues and provide useful information for the development of treatments for neuronal diseases.     

Notes on some African hepatic genera 1–5

The present study deals with five genera of hepatics in Africa, Isotachis Mitt., Anastrophyllum (Spruce) Steph., Tritomaria Schiffn. ex Loeske, Gymnocoleopsis (Schust.) Schust. and Lophozia (Dum.) Dum. All African populations of the genus Isotachis Mitt. are considered to be one species, I. aubertii (Schwaegr.) Mitt. Four species of Anastrophyllum (Spruce) Steph. (s.l.), A. auritum (Lehm.) Steph., A. piligerum (Nees) Spruce, A. subcomplicatum (Lehm. et Lindenb.) Steph. and A. minutum (Schreb.) Schust., and two species of Tritomaria Schiffn. et Loeske, T. camerunensis S. Arnell and T. exsecta (Schrad.) Schiffn. ex Loeske occur in Africa. Gymmocoleopsis multiflora (Steph.) Schust. represents a genus and species hitherto unreported for the African flora. Finally, five Lophozia (Dum.) Dum. species, L. argentina (Steph.) Schust., L. capensis S. Arnell, L. decolorans (Limpr.) Steph., L. hedbergii S. Arnell and L. tristaniana (S. Arnell) Váňa, are reported from central and southern Africa; two of these (L. argentina (Steph.) Schust. and L. decolorans (Limpr.) Steph.) represent the first reports from Africa.     

Overexpression of d-psicose 3-epimerase from Ruminococcus sp. in Escherichia coli and its potential application in d-psicose production

The d-psicose 3-epimerase (DPE) gene from Ruminococcus sp. was cloned and overexpressed in Escherichia coli. The recombinant protein was purified and characterized. It was optimally active at pH 7.5–8.0 and 60?°C. Activity was not dependent on the presence of metal ions; however, it became more thermostable with added Mn²⁺. The K _m of the enzyme for d-psicose (48?mM) was lower than that for d-tagatose (230?mM), suggesting that d-psicose is the optimum substrate. More importantly, the thermostability of the novel DPE from Ruminococcus is the strongest among all of the d-psicose and d-tagatose 3-epimerases and may be suitable for the industrial production of d-psicose from fructose.     

New insights on the role of free d-aspartate in the mammalian brain

Free d-aspartate (d-Asp) occurs in substantial amounts in the brain at the embryonic phase and in the first few postnatal days, and strongly decreases in adulthood. Temporal reduction of d-Asp levels depends on the postnatal onset of d-aspartate oxidase (DDO) activity, the only enzyme able to selectively degrade this d-amino acid. Several results indicate that d-Asp binds and activates N-methyl-d-aspartate receptors (NMDARs). Accordingly, recent studies have demonstrated that deregulated, higher levels of d-Asp, in knockout mice for Ddo gene and in d-Asp-treated mice, modulate hippocampal NMDAR-dependent long-term potentiation (LTP) and spatial memory. Moreover, similarly to d-serine, administration of d-Asp to old mice is able to rescue the physiological age-related decay of hippocampal LTP. In agreement with a neuromodulatory action of d-Asp on NMDARs, increased levels of this d-amino acid completely suppress long-term depression at corticostriatal synapses and attenuate the prepulse inhibition deficits produced in mice by the psychotomimetic drugs, amphetamine and MK-801. Based on the evidence which points to the ability of d-Asp to act as an endogenous agonist on NMDARs and considering the abundance of d-Asp during prenatal and early life, future studies will be crucial to address the effect of this molecule in the developmental processes of the brain controlled by the activation of NMDARs.     

Properties of the sugar carrier in Baker's yeast

Incubation ofSaccharomyces cerevisiae cells withd-galactose induced the formation of galactose-utilizing enzymes, among them a monosaccharide carrier, apparently synthesized as a proteinde novo. The synthesis of the carrier preceded that of galactokinase by as much as 2 h. The inducible carrier shows a preference for monosaccharides with an axial hydroxyl group at carbon 4 of theC1 chair conformation or at carbon 2 of the1C chair conformation. Through its mediation, some sugars normally poorly transported (d-galactose,d-fucose,l-xylose,l-arabinose) can enter into the entire cell water, occupying then one more kinetic (and morphological ?) compartment than before induction. Some other monosaccharides, readily transported even by a constitutive carrier system (e.g.l-sorbose,d-xylose,d-arabinose) share the newly synthesized carrier.     

Serine racemase: an unconventional enzyme for an unconventional transmitter

The discovery of large amounts of d-serine in the brain challenged the dogma that only l-amino acids are relevant for eukaryotes. The levels of d-serine in the brain are higher than many l-amino acids and account for as much as one-third of l-serine levels. Several studies in the last decades have demonstrated a role of d-serine as an endogenous agonist of N-methyl-d-aspartate receptors (NMDARs). d-Serine is required for NMDAR activity during normal neurotransmission as well as NMDAR overactivation that takes place in neurodegenerative conditions. Still, there are many unanswered questions about d-serine neurobiology, including regulation of its synthesis, release and metabolism. Here, we review the mechanisms of d-serine synthesis by serine racemase and discuss the lessons we can learn from serine racemase knockout mice, focusing on the roles attributed to d-serine and its cellular origin.     

Studien über dieJungermannioideae (Hepaticae) 6.Jungermannia Subg.Solenostoma: Europäische und nordamerikanische Arten

Dersechste Beitrag aus der Serie der vorbereiteten Studien über die SubfamilieJungermannioideae (Jungermanniaceae, Hepaticae) enthält die taxonomische Bearbeitung des Subg.Solenostoma (Mitt.)Amak. (GattungJungermannia L. emend.Dum.) in Europa (inkl. Kaukasus und Kleinasien) und Nordamerika. Im genannten Gebiet kommen 10 Arten vor, u. zw.J. caespiticia Lindenb.,J. caucasica Váňa,J. confertissima Nees,J. gracillima Sm.,J. handelii (Schiffn.)Amak.,J. jenseniana Grolle,J. lignicola (Schiffn.)Grolle,J. pyriflora Steph.,J. rubra Gott. exUnd. undJ. sphaerocarpa Hook. Die ArtJ. confertissima Nees (bisher alsSolenostoma levieri (Steph.)Steph. bezeichnet) gehört zu der SektionDesmorhiza Amak., alle anderen Arten gehören zu der SektionSolenostoma.