José Antonio López-Sáez

Antibacterial activity of pure flavonoids isolated from mosses

Seven pure flavonoids were isolated and identified from five moss species. The flavonoids were the flavones apigenin, apigenin-7-O-triglycoside, lucenin-2, luteolin-7-O-neohesperidoside, saponarine and vitexin; and the biflavonoid bartramiaflavone. Some of these flavonoids were shown to have pronounced antibacterial effects against Enterobacter cloaceae, E. aerogenes and Pseudomonas aeruginosa (minimal bacteriostatic concentration MIC in the range of 4-2048 micrograms/ml). Because of their antibacterial spectrum mainly active against Gram negative bacterial strains, responsible for severe opportunistic infections and resistant to common antibacterial therapy, these flavonoids may be important tools in antibacterial strategies.

The Posidonia oceanica marine sedimentary record: A Holocene archive of heavy metal pollution

The study of a Posidonia oceanica mat (a peat-like marine sediment) core has provided a record of changes in heavy metal abundances (Fe, Mn, Ni, Cr, Cu, Pb, Cd, Zn, As and Al) since the Mid-Holocene (last 4470yr) in Portlligat Bay (NW Mediterranean). Metal contents were determined in P. oceanica. Both, the concentration records and the results of principal components analysis showed that metal pollution in the studied bay started ca. 2800yr BP and steadily increased until present. The increase in Fe, Cu, Pb, Cd, Zn and As concentrations since ca. 2800yr BP and in particular during Greek (ca. 2680-2465cal BP) and Roman (ca. 2150-1740cal BP) times shows an early anthropogenic pollution rise in the bay, which might be associated with large- and short-scale cultural and technological development. In the last ca. 1000yr the concentrations of heavy metals, mainly derived from anthropogenic activities, have significantly increased (e.g. from ~15 to 47μg g(-1) for Pb, ~23 to 95μg g(-1) for Zn and ~8 to 228μg g(-1) for As). Our study demonstrates for the first time the uniqueness of P. oceanica meadows as long-term archives of abundances, patterns, and trends of heavy metals during the Late Holocene in Mediterranean coastal ecosystems.

Effects of seven pure flavonoids from mosses on germination and growth of Tortula muralis HEDW. (Bryophyta) and Raphanus sativus L. (Magnoliophyta)

Dried mosses (five moss species) were progressively extracted and subjected to a four-step Craig distribution. Seven pure flavonoids were isolated and identified. The flavonoids were the flavones apigenin, apigenin-7-O-triglycoside, lucenin-2, luteolin-7-O-neohesperidoside, saponarine and vitexin; and the biflavonoid bartramiaflavone and they were submitted to biological tests. The tests were performed in vitro on spore germination and protonemal growth of the moss Tortula muralis and on seed germination and root growth of Raphanus sativus. Flavonoids caused a decrease in the percentage of spore germination, protonemal development and root growth. In addition they caused morphological alterations, such as forked tips, swollen apices, rounded cells and early formation of brood cells in the protonemata. Data were discussed in relation to the presence of allelochemicals in mosses.

Holocene vegetation changes in NW Iberia revealed by anthracological and palynological records from a colluvial soil

Macroscopic charcoal, pollen and non-pollen palynomorphs were isolated from a colluvial soil located on a small hill in Campo Lameiro (NW Spain) in order to elucidate the vegetation history of the area and its relation to fire and human activities. The presence of macroscopic charcoal throughout the 2.10 m thick soil (42 samples) is evidence of frequent fires during the last c. 6300 years. The charcoal record was dominated by Quercus (probably Q. robur), Ericaceae (probably Arbutus unedo and Erica arborea) and Fabaceae (mainly Genista type). Abrupt changes in the charcoal assemblage are less explicit in the pollen sequence, probably as a result of pollen inflow from the downhill surroundings of the study site. Combined results indicated that the original oak woodland was gradually replaced by pyrophytic shrubs (Ericaceae and Fabaceae) as a result of fire recurrence. Non-pollen palynomorphs strongly suggested that vegetation was deliberately ignited by past human societies to facilitate grazing. No evidence of local agricultural practices was found. Episodes of accelerated shrubland expansion occurred c. 6000—5500 cal. BP, c. 4000—3500 cal. BP and c. 1700 cal. BP, the latter of which caused the definitive settlement of shrublands dominated by Ericaceae and Fabaceae which are nowadays widespread in NW Iberia.

Holocene environmental change and human impact in NE Morocco: Palaeobotanical evidence from Ifri Oudadane

The littoral site of Ifri Oudadane is one of the most important recently excavated sites in the Mediterranean Maghreb. The shelter presents Epipalaeolithic and Neolithic layers and therefore offers the possibility to investigate the Neolithic transition in the region. Besides introducing the archaeological context, this paper focuses on palaeobotanical data in order to reconstruct Holocene environmental change and human use of plant resources for the period c. 11 to 5.7 ka cal. BP. Results show intense landscape transformations resulting from anthropic and climatic factors. First human occupations start at the beginning of the Holocene with favourable conditions in this otherwise harsh semi-arid stretch of land. A wooded environment with evergreen sclerophyllous oaks and riparian forests is documented and exploited by hunter-gatherers. From c. 7.6 ka cal. BP farming activities are well attested together with significant human impact, herding pressure and a progressive decline of arboreal components. After 6.6 ka cal. BP conditions become less favourable and markers for aridity increase. Riparian taxa disappear (Alnus) or decrease (Fraxinus, Populus, Salix); shrubs (Tamarix) and grasses (Artemisia) increase with a degradation of forest into shrubland (macchia). During 6.6 and 6.0 ka cal. BP there is a general occupation gap in arid and semi-arid Morocco and evidence for that change is also found in the alluvial deposits of the Moulouya, NE Morocco. Indicators for food production decrease at the same time and the site is abandoned during the first half of the 6th millennium cal. BP.

Impact of late-Holocene aridification trend, climate variability and geodynamic control on the environment from a coastal area in SW Spain

A detailed pollen analysis has been carried out on two sediment cores taken from a marsh area located in the Doñana National Park, southwestern Spain. The studied sedimentary sequences contain a similar late Holocene record of vegetation and climate and show a progressive aridification trend since at least 5000 cal. yr BP, through a decrease in forest cover in this area. Long-term vegetation changes shown here (semi-desert expansion and Mediterranean forest decline) paralleled declining summer insolation. Decreasing summer insolation most likely impacted negatively on tree growing season as well as on winter precipitation in the area. Superimposed on the long-term aridification trend were multi-centennial scale periods characterized by forest reductions or increases in arid and halophytic plants that can be interpreted as produced by enhanced droughts and/or by local geodynamic processes. These are centered at ca. 4000, 3000–2500, and 1000 cal. yr BP, coinciding in timing and duration with well-known dry events in the western Mediterranean and other areas but could have also been generated by local sedimentary or geodynamic processes such as a marine transgression in a subsidence context and extreme wave events (EWEs). The alternation of persistent North Atlantic Oscillation modes probably played an important role in controlling these relatively humid–arid cycles.

Beyond nature: The management of a productive cultural landscape in Las Médulas area (El Bierzo, León, Spain) during pre-Roman and Roman times

Abstract This article focuses on the analysis of plant remains (seeds/fruits, charcoal, pollen, spores, and non-pollen palynomorphs) from two archaeological sites (pre-Roman and Roman) located in Las Médulas, a cultural landscape, in the northwestern part of the Iberian Peninsula. The article explores the way the communities living in the area managed their environment and the impact of productive activities on the landscape. This research has shown the multiplicity of needs this landscape satisfied and the various ways these communities managed the surrounding environment through different productive activities (agriculture, animal husbandry, and mining amongst others).

Modern pollen analysis: a reliable tool for discriminating Quercus rotundifolia communities in Central Spain

The paucity of modern pollen-rain data from the Iberian Peninsula is a signifi cant barrier to understanding the Late Quaternary vegetation history of this globally important southwestern mediterranean region. The relationships between current vegetation, the available environmental data and modern pollen are examined in Central Spain for both natural and human-induced vegetation types, as an aid for palaeoenvironmental reconstructions. A set of 60 surface moss polsters was sampled from different vegetation and land-use types in the Madrid autonomous region, and analysed to obtain modern pollen analogues of ancient cultural landscapes. Hierarchical cluster analysis (HCA) was used to divide the main pollen taxa into two major groups and ten subgroups representing the anthropic and natural vegetation types and the main communities within them. Statistically distinctive taxa were identifi ed using principal components analysis (PCA). The results indicate that human-infl uenced communities have pollen assemblages that are different from those of natural vegetation types. When modern pollen assemblages are compared, the three Holm oak (Quercus rotundifolia) communities of Madrid, representing two phytogeographical provinces and three subprovinces, are easily distinguishable by their pollen spectra.

The archaeology of the Middle Pleistocene deposits of Lake Eyasi, Tanzania

Ongoing archaeological research at North Lake Eyasi has produced a wealth of information, including a new hominid fossil and several archaeological sites dating to the end of the Middle Pleistocene. One of the sites (WB9) has been excavated and has produced evidence of multiple processes in its formation, including evidence of functional associations of stone tools and faunal remains which are scarce for this time period. The stone tool industry is based on a core and flake industry, which is not very diagnostic and attributed to MSA. Earlier heavy-duty tools classified as Sangoan may derive from the underlying Eyasi Beds. The stratigraphic provenience of previous fossil hominids is unknown. Surface collections from the Eyasi lake, thus, comprise two different sets of stone tools and fossils, which can only be clearly differentiated in the field. This advises against the use of previously curated collections as a homogeneous sample. Earlier definitions of the Njarasa industry should be revised. This work presents results on the paleoecology of the area and of its paleontological and archaeological information, with special reference to the excavation of WB9, the most complete site discovered in the area so far. This contributes to the limited information available about site functionality and hominid subsistential behaviour in East Africa during the end of the Middle Pleistocene. A technological study from WB9 also shows the variability of stone tool traditions at this time.

A late stone age sequence from West Ethiopia: The sites of K'aaba and Bel K'urk'umu (Assosa, Benishangul-Gumuz Regional State)

In this paper, the results of the test excavations in two rock shelters in the Central Ethiopian escarpment near the Sudanese border are presented. A continuous sequence of quartz lithic industry, from the lowest levels of K’aaba (with an archaic MSA-like industry of side-scrapers, Levallois- discoid cores and unifacial points) to the upper levels of Bel K’urk’umu (with a LSA industry, characterised by elongated flakes and end-scrapers, that still displays many archaic features such as centripetal flakes and cores) may be inferred. The escarpment’s mountainous and forested areas may have acted as a refuge zone from the end of the Pleistocene, when hyper-arid conditions deterred human occupation of the Sudanese plains nearby, and may also have been a cause for the cultural archaism of the late MSA groups, a case similar to others recorded in the African continent (South Africa, Zimbabwe, Nile Valley). The arrival of Sudanese pottery in the mid-Holocene period may be explained by the onset of arid conditions that drove “aqualithic” groups and early herders towards more humid areas. The conservative character of the late prehistoric cultural sequence derived from both sites is consistent with the resilient traditional nature of the Nilo- Saharan groups that currently settle the Ethio-Sudanese borderlands.