Population sequences in a high altitude alpine environment: Archaeological sites and historical and environmental time

Since 1998, a group of archaeologists have been studying the long-term history of human settlement and activity in the mid to high altitude (1800m and above) in theParc National des Ecrins (southern French Alps). This research has identified a number of different phases of settlement since the end of the last Ice Age (10,000 years ago). Whilst we accept that it is impossible to present the variation in actual number of people present in these marginal milieus, we can present an overview of waxing and waning of human activity in our study area. Our research demonstrates that poeple moved into these high altitude zones as soon as the glaciers retreated. The first phase of extensive and relatively intensive activity dates to the Bronze Age (c. 2000 BC). During the Iron Age and Roman period there appears to have been a relative reduction in the level of activity. However, from the early medieval period onwards there is incontrovertible evidence for a substantial increase in activity. This culminates with the emergence of a “busy” landscape during the post-medieval period when mining and pastoral activities were at their peak.     

STORAGE AND STRUCTURAL PRODUCTS FORMED DURING PHOTOSYNTHESIS IN THE SIPHONOUS ALGA CAULERPA SIMPLICIUSCULA(CHLOROPHYCEAE)1

The distribution of radioactivity into storage and intermediary metabolites during photosynthesis over periods of up to three hours was followed in the siphonous green alga Caulerpa simpliciuscula C. Ag. After the first hour, almost all the carbon assimilated was recovered as insoluble 1,4-α-glucan. There was rapid movement of carbon into insoluble 1,3-β-glucans during the first 20 min of photosynthesis, but little additional carbon moved into these compounds after that time. This contrasted with the movement of carbon into the soluble 1,3-β-glucan fraction, which continued for 2 h. Sucrose accumulated very little ¹⁴C during the entire period of photosynthesis. There was a very slow transfer of ¹⁴C into lipid throughout the period but the rate was linear. Protein labelling showed a lag of 2 h before it reached the same rate of ¹⁴C accumulation as shown by the lipid initially. It is suggested that the distribution of radioactivity can be explained in part by proposing that the tissue is in the latter stages of recovery from the wounding which look place at the time of dividing the thallus into sections.     

The introduction of Old World crops (wheat, barley and peach) in Andean Argentina during the 16th century a.d.: archaeobotanical and ethnohistorical evidence

It was believed for a long time that the first Old World crops were introduced to the northwest of Argentina in a.d. 1550 during the foundation of Barco, and that the indigenous people incorporated them into their subsistence almost passively. However, since wheat, barley, and peach have been recovered from El Shincal, an Inka (Inca) administrative centre, new questions have arisen about who first brought these crops to the study region, as well as about where they were grown for the first time and which routes they followed after that. This paper will try to solve these questions during a period ranging from the 16th to the 18th century. This time span, although arbitrary, is consistent with the major damage to the original social structure caused by the Spaniards to the local indigenous populations. Our approach includes the comparison of ethnohistorical with archaeobotanical evidence. It is concluded that the first Old World crops were brought from Chile to Santiago del Estero by Spanish soldiers in a.d. 1556, and to Londres in a.d. 1558. These crops were taken up by local indigenous people during the period of the encomenderos and used to carry out a pachamanca ceremony at El Shincal during a Diaguita rebellion. Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Proteomic analysis of chicory root identifies proteins typically involved in cold acclimation

Chicory (Cichorium intybus) roots contain high amounts of inulin, a fructose polymer used as a storage carbohydrate by the plant and as a human dietary and prebiotic compound. We performed 2‐D electrophoretic analysis of proteins from root material before the first freezing period. The proteins were digested with trypsin and the peptides analyzed by MS (MALDI‐TOF/TOF). From the 881 protein spots analyzed, 714 proteins corresponded to a database accession, 619 of which were classified into functional categories. Besides expected proteins (e.g. related to metabolism, energy, protein synthesis, or cell structure), other well‐represented categories were proteins related to folding and stability (49 spots), proteolysis (49 spots), and the stress response (67 spots). The importance of abiotic stress response was confirmed by the observation that 7 of the 21 most intense protein spots are known to be involved in cold acclimation. These results suggest a major effect of the low temperature period that preceded root harvesting.     

新疆哈巴河桦木属湿地3600年以来的植被变化和人类活动

湿地是水陆相互作用形成的独特自然综合体,对全球气候变化敏感,尤其是干旱半干旱区分布的湿地对自然环境和人类活动的响应更为显著。基于新疆哈巴河地区桦木林湿地人工开挖130 cm深的地层剖面,结合较高时间分辨率的¹⁴C测年数据和孢粉组合,揭示出该区3600年来曾经历5个时段的植被变化和人类活动的影响。3540—3430 cal a BP期间,该区以蒿属(Artemisia)等旱生植物为主,湿地尚未形成;3430—2640 cal a BP期间,局地小环境较湿润,湿生草本和以沼泽蕨(Thelypteris palustris)为代表的蕨类植物大量生长,落叶阔叶的桦木属(Betula)植物开始出现;至2640—660 cal a BP期间,浅水湿地开始形成,桦木属植物迅速扩张,但在大区域仍分布着由藜科(Chenopodiaceae)和蒿属等为主要组成的荒漠植被;尤其在660—210 cal a BP期间,桦木属成为森林的优势种;值得关注的是,近200年以来,该区以藜科为代表的草本植物增多,而桦木林出现萎缩。通过对选取的典型局域湿地不同历史时期环境变化和人类活动影响的研究,揭...     

Mutational analysis of morphogenesis of the maize embryo

Morphogenesis of the maize embryo is controlled by many genes. A group of 51 embryo-specific (emb) mutations representing at least 45 independent mutation events and many different gene loci have been isolated from active Robertson's Mutator stocks. The authors have reported previously that the embryo phenotype of 27 of these mutations, characterized by examining mature embryos in fresh dissection. The maximal development capacity of the 24 emb mutations are reported here which have not been reported previously. All result in retarded embryos that are morphologically abnormal. Three of the mutants are blocked during the first phase of morphogenesis, the period in which the basal-apical asymmetry is established and the embryo is regionalized into suspensor and embryo proper. Nineteen mutants are blocked during the second phase, the period in which radial asymmetry appears, the embryonic axis is established at a different angle than the original basal-apical axis of the zygote and the vegetative organ primordia of the adult plant make their first appearance. Two mutants are blocked or altered during the third phase, the period in which vegetative structures are elaborated. Some of the mutants affected in the first phase of morphogenesis may have defective mechanisms for establishing basal-apical asymmetry, including possibly the asymmetric distribution of morphogenic determinants. Similarly, some of the mutants affected in the second phase may be altered in the mechanisms establishing radial asymmetry and the origin of the meristems. Mutations of the first type may act as early as the first cell division when the zygote undergoes a transverse division, while mutations of the second type are likely to act during the proembryo and transition stages. Both types include mutations affecting embryo pattern formation. Mutations affecting the third phase of morphogenesis may identify genes regulating reiterative morphogenic processes of vegetative plant development and events of embryo maturation. This group of 24 mutations is like that reported previously in representing genes that are crucial to embryo morphogenesis.     

Studies on the vegetation history of Lake Varna region,northern Black Sea coastal area of Bulgaria

On the basis of pollen analytical investigations of two cores from Lake Varna and Lake Beloslav, the vegetation history of the Lake Varna region is traced back to the beginning of the 6th millennium B.C. A two-fold zoning system is used whereby the pollen diagrams are divided into pollen zones, based on tree migration patterns, and settlement periods. Pollen zone 1 is characterised by the absence of Carpinus betulus and Fagus sylvatica. The spread of hornbeam started at ca. 6500 B.C. (pollen zone 2) and beech at ca. 6200 B.C. (pollen zone 3), the latter being the last tree to spread into the region and considerably enrich the forests of the study area. Of the many pollen taxa representing plants that are favoured by open habitats and hence potentially indicative of human impact, only a few taxa are regarded as reliable indicators of human activity. These include above all Triticum-type, and also Secale and to a certain extent Plantago lanceolata, Rumex and Polygonum aviculare. The spatial pattern of settlements is somewhat different in the areas represented by the two profiles. At both sites the first period of settlement occurred during the 6th millennium B.C. (early Neolithic). After the Neolithic period, the main settlement periods of the Eneolithic and the Early and Middle Bronze Age are recorded. On the other hand, land-use history during the Greek and Roman periods is poorly recorded. Studies on the stratigraphy, diatoms and molluscs indicate that the sixth Black Sea transgression (6500–5800 B.C.), which reached –10 m, had considerable influence on the limnological environment.     

Earliest Holocene vegetation history and island biogeography of the Isle of Man, British Isles

Aim To present radiocarbon dated early Holocene pollen analytical data from two sites on the northern plain of the Isle of Man and to discuss the implications of the vegetation history in relation to severance of the island from the British Isles and to identify further evidence for divergent biogeographical development previously exemplified by the survival and apparent dwarfism of late glacial Megaloceros giganteus (Giant Deer). Location The Isle of Man, British Isles. Methods Pollen analysis and AMS radiocarbon dating of late glacial to early Holocene lake sequences at Pollies and Curragh‐y‐Cowle on the northern plain of the Isle of Man. Results The pollen data indicate a prolonged period of pre‐woodland vegetation after the late Glacial/Holocene transition, which lasted for most of the first post‐glacial millennium. This persistence of pre‐forest environments meant that the expansion of Betula woodland occurred later in this part of the Isle of Man than in adjacent areas of Britain and Ireland. Conclusions The Isle of Man, in the northern Irish Sea, was isolated from Britain during the late Glacial period perhaps explaining the delayed arrival of tree species. Delayed rise of the Holocene forest compared with surrounding regions probably reflects severance of the land‐bridge with Cumbria, but also could be a function of climate changes during the early Holocene and local environmental conditions. Late survival and the dwarfism of the Megaloceros giganteus (Giant Deer) fauna is another example of biogeographical divergence during the early Holocene/late Glacial of the Isle of Man. The delayed afforestation and absence of human hunters in the Manx early Holocene offers a permissive environmental context for the as yet unproven survival of Megaloceros into the early Holocene.     

The growth and partition of cell membranes during synchronized division cycle of Caulobacter crescentus

Summary The growth and division of cell membranes in Caulobacter crescentus has been studied. This microorganism divides into flagellated and stalked cells which are easily separated by centrifugation. The biosynthesis and partition of membranes was studied by labeling the proteins with [³H]-leucine and the lipids with [³²P]. The membranes were prepared from cell spheroplasts. They further purified on a sucrose gradient.The data obtained show changes of the rate of synthesis of membranes in C. crescentus during the first synchronized division cycle (110 min): the rate is faster in the first 70 min and it drops by 26% during the following 40 min. During the period of faster synthesis the flagellated cells are changing into stalked cells while doubling in size.There is also an intracellular pool of membrane precursors the quantity of which almost doubles as the rate of membrane synthesis decreases, i.e., before cell division.The macromolecules constituting the membranes are not degraded.After division, in each membrane of the two morphologically different cell types the specific radioactivity is 50% of that of the parent cell membranes.     

Hormonal stimulation of tyrosinase activity in human foreskin organ cultures

Summary A human foreskin organ culture system has been developed to study the response of human skin to hormonal stimulation. Foreskins are maintained in culture on floating plastic supports which allows the epidermal surface to be exposed to air while the dermis is bathed in nutrient medium. Both black and white human foreskins can be maintained in organ culture for at least 1 wk with no change in the tissue structure or cell viability as determined by histochemical staining and by dopa reaction staining. Tyrosinase activity in both black and white human foreskin cultures decays markedly during the first 2 d of culture to a new steady state level which remains stable throughout the culture period. Both black and white foreskin cultures consistently demonstrate 2- to 10-fold increases in tyrosinase activity when treated with theophylline (1 mM). Approximately 90% of all skin cultures examined showed an increase in enzyme activity when treated with this phosphodiesterase inhibitor. Dibutyryl cAMP (0.1 mM) and [Nle⁴, D-phe⁷]-alpha MSH (10⁻⁸ M), were also found to markedly stimulate tyrosinase activity in some skin cultures, whereas alpha-MSH and prostaglandin E₁ produced only an inconsistent and small increase in the activity of the enzyme. Histamine (1 μM), vitamin D₃ (1 μM), and retinoic acid (1μM) failed to stimulate tyrosinase activity in either white or black foreskin cultures. This hormone-responsive organ culture system can be utilized to characterize the molecular processes responsible for the regulation of tyrosinase and pigmentation in human skin. This work was supported by a research contract from the Oklahoma Center for the Advancement of Science and Technology (OCAST) and by a research grant from the Presbyterian Health Foundation.     

Vibrio cholerae phosphatases required for the utilization of nucleotides and extracellular DNA as phosphate sources

Phosphate is essential for life, being used in many core processes such as signal transduction and synthesis of nucleic acids. The waterborne agent of cholera, Vibrio cholerae, encounters phosphate limitation in both the aquatic environment and human intestinal tract. This bacterium can utilize extracellular DNA (eDNA) as a phosphate source, a phenotype dependent on secreted endo‐ and exonucleases. However, no transporter of nucleotides has been identified in V. cholerae, suggesting that in order for the organism to utilize the DNA as a phosphate source, it must first separate the phosphate and nucleoside groups before transporting phosphate into the cell. In this study, we investigated the factors required for assimilation of phosphate from eDNA. We identified PhoX, and the previously unknown proteins UshA and CpdB as the major phosphatases that allow phosphate acquisition from eDNA and nucleotides. We demonstrated separable but partially overlapping roles for the three phosphatases and showed that the activity of PhoX and CpdB is induced by phosphate limitation. Thus, this study provides mechanistic insight into how V. cholerae can acquire phosphate from extracellular DNA, which is likely to be an important phosphate source in the environment and during infection.     

Xenopus leads the way: Frogs as a pioneering model to understand the human brain

From its long history in the field of embryology to its recent advances in genetics, Xenopus has been an indispensable model for understanding the human brain. Foundational studies that gave us our first insights into major embryonic patterning events serve as a crucial backdrop for newer avenues of investigation into organogenesis and organ function. The vast array of tools available in Xenopus laevis and Xenopus tropicalis allows interrogation of developmental phenomena at all levels, from the molecular to the behavioral, and the application of CRISPR technology has enabled the investigation of human disorder risk genes in a higher‐throughput manner. As the only major tetrapod model in which all developmental stages are easily manipulated and observed, frogs provide the unique opportunity to study organ development from the earliest stages. All of these features make Xenopus a premier model for studying the development of the brain, a notoriously complex process that demands an understanding of all stages from fertilization to organogenesis and beyond. Importantly, core processes of brain development are conserved between Xenopus and human, underlining the advantages of this model. This review begins by summarizing discoveries made in amphibians that form the cornerstones of vertebrate neurodevelopmental biology and goes on to discuss recent advances that have catapulted our understanding of brain development in Xenopus and in relation to human development and disease. As we engage in a new era of patient‐driven gene discovery, Xenopus offers exceptional potential to uncover conserved biology underlying human brain disorders and move towards rational drug design.     

Effects of previous experience and age-related changes on host eggs parasitization by <Emphasis Type="Italic">Trichogramma buesi</Emphasis> Voegele (Hymenoptera,Trichogrammatidae) females

The influence of the previous parasitization experience and age-related endogenous changes on the parasitization of Sitotroga cerealella Oliv. (Lepidoptera, Gelechiidae) eggs by Trichogramma buesi Voegele (Hymenoptera, Trichogrammatidae) females was estimated in the laboratory conditions. The experiment included two exposures separated by a period lasting from 0 to 20 days at 20°C. The first exposure lasted for 4 h and was conducted at a temperature of 25°C which promoted parasitization. The second exposure lasted 48 h and was conducted at a temperature of 15°C which inhibited parasitization. The survival of the control females (deprived of the hosts at the first exposure) was slightly higher than that of the experimental females. The mean number of mature eggs and the mean fecundity during the second exposure were lower in females that parasitized during the first exposure than in the controls and in females that rejected the host during the first exposure. The proportion of T. buesi females that parasitized S. cerealella eggs during the second exposure was much higher among the females that started parasitization during the first exposure than among controls and among those that rejected the host during the first exposure. This effect of the previous parasitization experience on the following parasitization of the same host species persisted for 16 days. However, on day 20 after the first exposure the proportion of the parasitizing individuals among the experienced females was the same as among the controls and those that rejected the host during the first exposure. This sharp decay in the effect of experience coincided with an increase in mortality and with a decrease in the proportion of parasitizing females among the controls. Thus, the experience-induced behavioral changes per se could be considered as practically permanent, since the period of their persistence is close to the female active life span.     

Sexual reproduction and life cycle of Ceratium furcoides (Dinophyceae) in situ in the lake Plußsee (F.R.)

The life cycle of Ceratium furcoides (Levander) Langhans which features sexual reproduction is described for the first time in situ from the lake Plußsee (northern West Germany). Anisogamic copulation occurs during the bloom period in July–August by incorporation of the male gamete by the female gamete, resulting in an overwintering planozygote. The planozygote develops into a benthic hypnozygote which germinates in spring to establish a planomeiocyte. The morphology and structure of the stages of the life cycle are described using light and scanning electron microscopy.     

STUDIES ON SARGASSUM. I. A LIGHT MICROSCOPIC EXAMINATION OF THE WOUND REGENERATION PROCESS IN MATURE STIPES OF S. FILIPENDULA

Regrowth from wounded stipe explants of Sargassum can be divided into four stages based on cytological changes. The first stage involves changes associated with the wound reactions and the formation of a wound epidermis. The second stage includes the formation of a well defined medullary pit with meristematically active cells around its periphery. Several “bud primordia” are also formed which begin to grow by cell division towards the wound surface. The third stage involves a period of internal tissue differentiation in the “bud primordia” such that mitotic activity is localized in the bud tip and the basal cells grow by cell elongation. The fourth stage marks a major change in the morphology of the regeneration branch from a tubular structure to that of a flattened blade. This change in morphology is preceded by the formation of an apical pit around which the flattened growth appears to be organized.     

Vegetation dynamics of south-western Italy in the last 28 kyr inferred from pollen analysis of a Tyrrhenian Sea core

A continuous pollen record covering the last 28 kyr was obtained from core C106 collected in the Bay of Salerno in the southern Tyrrhenian Basin, seven radiocarbon dates and the recognition of two tephra layers (Y3 and Pompeii Pumice) providing good chronological constraints. The clear climatic signal given by the pollen spectra integrated by isotopic data, combined with comparisons with other Mediterranean sites, allowed the Last Glacial, Late Glacial and Holocene periods to be distinguished in the core. In particular, the Last Glacial period is characterised by large quantities of herbaceous and steppe elements such as Artemisia. The beginning of the Late Glacial has been correlated with the first increase of deciduous Quercus and the reduction of steppe and herbaceous elements. The Younger Dryas event is recorded only by oxygen isotopes while the vegetation does not seem to change, as in other Mediterranean sites. The Holocene corresponds to rich deciduous and evergreen forests. The first features which could be interpreted as signs of human presence are represented by a few grains of Juglans, Castanea and cereal-type while intensive olive cultivation and deforestation seem to fall within the Middle Ages. Received October 10, 2001 / Accepted June 20, 2002 Correspondence to: Elda Russo Ermolli     

Cranial morphology and development: new light on the evolution of language

A hypothesis is presented which may explain within a single framework both the large behavioural differences and the large differences in head morphology between the great apes and humans. All these differences can be parsimoniously explained by a shift of few regulatory genes controlling the onset of the division of late migrating neurons in the human cortex. This simple shift resulted in the following effects: 1) the neurocranium responded to brain enlargement by increasing mineral deposition on its external surface, increasing its overall size and mass. 2) This increase in the braincase was largely achieved by developmental reabsoption of the face bones. 3) The relative shift in growth between these two skull components also induced a rearrangement at the basicranium level. This brought about the facial orthognatism of modernHomo and, as a mechanical by-product, the descent of the larynx into the throat. Brain enlargement led to a large increase in cognitive capacity, and as a developmental byproduct, produced a mechanical organ preadapted for speech, as well as bringing about the reduction of canines and the origin of the chin. In this study, the phylogenetic basis, the selective pressures, and the behavioural consequences of this process during hominization are examined. Cognitiveversus communicative aspects of human language are distinguished and discussed. Cognitive capacities were the first to be selected due to the survival advantage of mapping huge territories during the expansion of the Plio-Pleistocene savanna ecotone. The present hypothesis is then compared with current theories leading to the conclusion that it is a more parsimonious explanation. It integrates data from a wide array of fields of human biology, pathology and clinical medicine, all assessed from evolutionary and ecological perspectives.