Phytogeography of seaweeds of the Azores

189 species of seaweeds have been recorded for the Atlantic archipelago of the Azores (114 Rhodophyceae, 41 Phaeophyceae and 34 Chlorophyceae). Ten of these have been described as endemic algae. The taxonomic status of these “endemics” is far from clear, however. Studies on the relatedness of this seaweed flora to seaweed floras of surrounding areas using clustering methods indicate its intermediary position between the seaweed floras of the subtropical Macaronesian Islands (Canaries Madeira and Salvages) on the one side and those of the warm temperate Eurafrican coasts on the other side. The geographic position of the Azores is NW of the other Macaronesian Archipelagos and thus nearer to the American coast. The Gulf stream may easily transport seaweeds from the Carribean to the Azores. Nevertheless, the number of species of these islands in common with the American Atlantic coast is much lower than with, for example, the W. Mediterranean. Of one group of seaweeds, viz. algae with a strictly warm temperature distribution, not a single species occurs likewise on American coasts. This absence is probably explicable because of the narrow temperature range for survival of these seaweeds. Temperatures of surface waters around the Azores during pleistocene glaciations were not much lower than they are at present. Nevertheless, it can be supposed that a number of seaweeds now occurring in the Azores have become extinct during the last glaciation. Paper presented at the XIV International Botanical Congress (Berlin, 24 July–1 August, 1987), Symposium 6-15, “Biogeography of marine benthic algae”. CANCAP-project. Contributions to the zoology, botany and paleontology of the Canarian-Cape Verdean region of the North Atlantic Ocean. No. 67.     

Local floras of the northwestern Putorana Plateau: A comparative analysis

The study has revealed the diversity of vascular plants in two altitudinal belts in the upper reaches of the Kygam, Morgel’, and Lontoko rivers. Life forms and geography and ecology of the floras were analyzed for each vegetative belt. Species compositions of the three local floras were compared. The results showed that the Lontoko goletz and subgoletz belts are floristically different from the Kygam and Morgel’ goletz and subgoletz belts. According to the percentages of latitudinal elements, the Kygam floras are more similar to either Lontoko or Morgel’ floras than the latter are to each other. According to the percentages of species ecological groups and life forms, the Lontoko goletz and subgoletz belts are floristically similar to the Kygam goletz and subgoletz belts and different from the Morgel’ goletz and subgoletz belts.     

The steps of vascular plant and land ecosystem evolution

Basal steps of higher plant evolution are reconstructed by the structure of their conducting tissues. Historically, transport networks are derivatives of buffer zones for symbiotic exchange between prokaryotic pro-cursers. Two symbiogenetic acts (prochlorophytes + protists → higher algae; marine algae + fungi → higher land plants) are fixed in plant body by two networks for water transport. Descending phloem arises in phylogenesis from the membrane capsule of cyanobacteria. Fungi mycelium is a source of rising xylem exudates. The diversity of plant life forms is considered as a sequence of adaptive evolution of algo-myco-bacterial complex. Relationship to global chronical of climate events is shown by the specificities of Paleogene thermal floras and Neogene cold floras. The trends of plant genome size evolution are discussed.     

OCCURRENCE OF ENDOSYMBIOTIC BACTERIA IN MARINE DINOFLAGELLATES1,2

The marine dinoflagellates Gymnodinium splendens (photosynthetic) and Cryptothecodinium cohnii (heterotrophic) harbor abundant endosymbiotic bacterial floras. Some general observations are made on their characteristics, and on this symbiotic relationship in other protists.     

The significance of pollen signal in present-day marine terrigenous sediments: The example of the Gulf of Lions (western Mediterranean Sea)

Terrigenous marine and continental sediments constitute pollen reservoirs able to fulfil the lack of Pleistocene data extracted from autochtonous lacustrine sediments for palaeovegetation reconstructions. Nevertheless, it is essential to constrain the signification of the pollen signal in such still under-exploited sediments. This article introduces a study carried out on the shelf of the Gulf of Lions. It aims at (1) highlighting the transport of pollen grains and the signification of the record in that area as well as at (2) discussing the pollen transport in various sedimentary contexts. The present study was carried out on surface water of the Rhone River, sea water and surface sediments of the shelf of the Gulf of Lions. The pollen content of the Rhone River and of its plume is in agreement with the season of sampling. On the contrary, the other samples of sea water did not contain any pollen grain. The samples from the surface sediments of the shelf are very rich in pollen grains and evidence the absence of sorting by currents except for Pinus. Indeed, its relative abundance increases when the fluvial impact decreases. The pollen signal (except Pinus) records the phytogeographic changes linked to the different drainage basins. The riparian woodland is over-represented at the Rhone River mouth. In front of the Pyreneo-languedocian rivers, Mediterranean xerophytes pollen grains are more abundant. From these results and from others taken in the literature, a model of pollen transport is built: all thin terrigenous sediments contain pollen grains essentially transported by rivers while autochthonous sediments (i.e., found in closed lakes or marine pelagic sediments) contain pollen grains brought by wind. Small closed lakes (or peat bogs) pollen spectra document local floras while those from pelagic marine sediments document floras from several hundred square kilometres.     

All-trans retinoic acid induces free radical generation and modulate antioxidant enzyme activities in rat sertoli cells

In this work we investigated the effects of retinoic acid (RA) in Sertoli cells. Sertoli cells isolated from 15-day-old Wistar rats were previously cultured for 48 h and then treated with RA for 24 h. RA at high doses (1–10 μM) increased TBARS levels and induced a decrease in cell viability. At low doses (0.1–100 nM) RA did not increase TBARS level. RA also did not increase cell death at these doses. In order to investigate changes in antioxidant defenses we measured the CAT, SOD and GPx activities in Sertoli cells treated with RA. Compared to control, RA increased around 200% SOD activity in all doses tested (0.1–100 nM); GPx activity was increased 407.49, 208.98 and 243.88% (0.1, 1 and 10 nM, respectively); CAT activity was increased 127% with RA 1 nM. To clarify if RA induces ROS production per se, we performed experiments in vitro using 2-deoxyribose as specific substrate of oxidative degradation by ^•OH radical as well as TRAP assay. RA at 10 μM increased 2-deoxyribose degradation, suggesting that some of the RA-induced effects are mediated via ^•OH formation. Furthermore, the total reactive antioxidant potential (TRAP) of the RA was determined. At low concentrations RA has induced no redox activity. Conversely, higher concentration of RA (1–10 μM) increased chemiluminescence. The chemiluminescence produced was directly proportional to radical generation. We provide, for the first time, evidence for a free radical generation by RA. Our results demonstrated that RA plays an important role in Sertoli cells and these effects appear to be mediated by ROS.     

Differential expression of the FAK family kinases in rheumatoid arthritis and osteoarthritis synovial tissues

The focal adhesion kinase (FAK) family kinases, including FAK and proline-rich kinase 2 (Pyk)2, are the predominant mediators of integrin αvβ3 signaling events that play an important role in cell adhesion, osteoclast pathology, and angiogenesis, all processes important in rheumatoid arthritis (RA). Using immunohistochemical and western blot analysis, we studied the distribution of phospho (p)FAK, pPyk2, pSrc, pPaxillin and pPLCγ in the synovial tissue (ST) from patients with RA, osteoarthritis (OA) and normal donors (NDs) as well as in RA ST fibroblasts and peripheral blood differentiated macrophages (PB MΦs) treated with tumor necrosis factor-α (TNFα) or interleukin-1β (IL1β). RA and OA STs showed a greater percentage of pFAK on lining cells and MΦs compared with ND ST. RA ST fibroblasts expressed pFAK at baseline, which increased with TNFα or IL1β stimulation. Pyk2 and Src were phosphorylated more on RA versus OA and ND lining cells and MΦs. pPyk2 was expressed on RA ST fibrobasts but not in MΦs at baseline, however it was upregulated upon TNFα or IL1β activation in both cell types. pSrc was expressed in RA ST fibroblasts and MΦs at baseline and was further increased by TNFα or IL1β stimulation. pPaxillin and pPLCγ were upregulated in RA versus OA and ND lining cells and sublining MΦs. Activation of the FAK family signaling cascade on RA and OA lining cells may be responsible for cell adhesion and migration into the diseased STs. Therapies targeting this novel signaling pathway may be beneficial in RA.     

瑞典河漫滩草甸植被的数量分类和排序

本文用目前各国学者广泛使用的一些数量分类和排序方法对瑞典河漫滩草甸样地资料进行了分类和排序。所用的方法包括多元等级聚合分类(TABORD程序),多元等级分划分类(TWINSPAN程序),PCA排序(ORDINA程序),RA和DCA排序(DECORANA程序)。研究结果表明可以把28个样地分为6个群落类型,它们的分布格局是与土壤水分梯度密切相关的。此外本文还对数量分类和排序方法在植物群落学研究中的应用以及所用方法的比较进行了讨论。     

The distribution of seaweed floras in the tropical and subtropical Atlantic Ocean: a quantitative approach

Records of nearly 1500 species of marine algae present in over 80 countries, states, and islands of the tropical and subtropical Atlantic were analyzed to ascertain the relationships between their floras. Association analysis was unsatisfactory, cluster analysis was better, but, of the classificatory methods, indicator species analysis was best. However, the most meaningful results were obtained by ordination using reciprocal averaging. This method demonstrates that after the separation of the marine flora of South-West Africa (Namibia), two clearly defined groupings representing the eastern Atlantic and the western Atlantic are apparent. On the western side, the floras, apart from that of Uruguay, are a relatively close-knit group, except that the northern coast of the Gulf of Mexico together with the southern Atlantic States of the U.S.A. are distinct from the southern Gulf of Mexico and Caribbean groups. On the eastern side of the Atlantic the floras are less closely related. A well-marked tropical group extends from Gambia to Cameroun but does not include the Gulf of Guinea islands which form another group with Angola. This latter group is transitional to the colder water floras lying northwards of Senegal and south of Angola.     

Genetics of rheumatoid arthritis: what have we learned?

Rheumatoid arthritis (RA) is a chronic autoimmune disease affecting 0.5–1% of the population worldwide. The disease has a heterogeneous character, including clinical subsets of anti-citrullinated protein antibody (ACPA)-positive and APCA-negative disease. Although the pathogenesis of RA is poorly understood, progress has been made in identifying genetic factors that contribute to the disease. The most important genetic risk factor for RA is found in the human leukocyte antigen (HLA) locus. In particular, the HLA molecules carrying the amino acid sequence QKRAA, QRRAA, or RRRAA at positions 70–74 of the DRβ1 chain are associated with the disease. The HLA molecules carrying these “shared epitope” sequences only predispose for ACPA-positive disease. More than two decades after the discovery of HLA-DRB1 as a genetic risk factor, the second genetic risk factor for RA was identified in 2003. The introduction of new techniques, such as methods to perform genome-wide association has led to the identification of more than 20 additional genetic risk factors within the last 4 years, with most of these factors being located near genes implicated in immunological pathways. These findings underscore the role of the immune system in RA pathogenesis and may provide valuable insight into the specific pathways that cause RA.     

Cardiovascular risk in rheumatoid arthritis versus osteoarthritis: acute phase response related decreased insulin sensitivity and high-density lipoprotein cholesterol as well as clustering of metabolic syndrome features in rheumatoid arthritis

Rheumatoid arthritis (RA) patients experience a markedly increased frequency of cardiovascular disease. We evaluated cardiovascular risk profiles in 79 RA patients and in 39 age-matched and sex-matched osteoarthritis (OA) patients. Laboratory tests comprised ultrasensitive C-reactive protein (CRP) and fasting lipids. Insulin sensitivity (IS) was determined by the Quantitative Insulin Sensitivity Check Index (QUICKI) in all OA patients and in 39 of the RA patients. Ten RA patients were on glucocorticoids. RA patients exercised more frequently than OA patients (χ² = 3.9, P < 0.05). Nine RA patients and one OA patient had diabetes (χ² = 4.5, P < 0.05). The median CRP, the mean QUICKI and the mean high-density lipoprotein (HDL) cholesterol were 9 mg/l (range, 0.5–395 mg/l), 0.344 (95% confidence interval [CI], 0.332–0.355) and 1.40 mmol/l (95% CI, 1.30–1.49 mmol/l) in RA patients, respectively, as compared with 2.7 mg/l (range, 0.3–15.9 mg/l), 0.369 (95% CI, 0.356–0.383) and 1.68 mmol/l (95% CI, 1.50–1.85 mmol/l) in OA patients. Each of these differences was significant (P < 0.05). After controlling for the CRP, the QUICKI was similar in RA and OA patients (P = 0.07), while the differences in HDL cholesterol were attenuated but still significant (P = 0.03). The CRP correlated with IS, while IS was associated with high HDL cholesterol and low triglycerides in RA patients and not in OA patients. A high CRP (≥ 8 mg/l) was associated with hypertension (χ² = 7.4, P < 0.05) in RA patients. RA glucocorticoid and nonglucocorticoid users did not differ in IS and lipids (P > 0.05). Excess cardiovascular risk in RA patients as compared with OA patients includes the presence of decreased IS and HDL cholesterol in RA patients. The latter is only partially attributable to the acute phase response. The CRP, IS, HDL cholesterol, triglycerides and hypertension are inter-related in RA patients, whereas none of these relationships were found in OA patients.     

The proliferative effects of retinoic acid on primary cultures of adult rat type II pneumocytes depend upon cell density

Retinoic acid (RA) is important for maintaining integrity of alveolar epithelial cells, but the mechanism has not been defined. We cultured type II pneumocytes at confluent, high cell density (10⁴ cells/mm²) and found that RA (10⁻⁶ M) inhibited thymidine incorporation to 60% of control, despite a dose-dependent increase in epidermal growth factor receptor (EGFR) levels. However, at lower, subconfluent density (10² cells/mm²), RA stimulated thymidine incorporation to 280% of control. EGF increased thymidine incorporation at concentrations as low as 0.1 ng/mL, but no further increase was observed at higher concentrations up to 100 ng/mL. In subconfluent cells co-treated with EGF (100 ng/mL) and increasing concentrations of RA (10⁻⁸ M–10⁻⁵ M RA), thymidine incorporation was significantly greater at all concentrations than RA alone, with greatest increases observed at 10⁻⁷ (422% of control) and 10⁻⁶ (470% of control) M RA. In summary, the effects of RA on thymidine incorporation are sensitive to changes in cell density. RA inhibits thymidine incorporation at high cell density and stimulates thymidine incorporation at low density. RA increases EGFRs in cultured type II pneumocytes, and EGF stimulates thymidine incorporation independent of the cultured cell density. These data may help to explain how RA mediates lung repair in vivo.     

The possible significance of long-range dispersal for the biogeography of seaweeds

Indirect evidence of the existence of long-distance dispersal of seaweeds is provided by the fact that mid-oceanic islands of volcanic origin are inhabited by well-developed seaweed floras which could reach these islands only overseas from continental donor areas. For instance, the flora of Tristan da Cunha (S. Atlantic Ocean) was established by long-distance dispersal in less than 1 million years (the approximate age of the island); the seaweed flora of the Faeroes (N. Atlantic Ocean) could be constituted in less than 10,000 years (the end of the Pleistocene ice cover of these islands). There is no evidence for either supporting or discounting the possible role of planktonic stages of seaweeds (spores, propagules, zygotes) in the long-distance dispersal of seaweeds. There is, however, some evidence of long-distance dispersal as floating plants, or as plants attached to floating objects (including floating algae). There are a few examples of “artificial” long-range dispersal by man (possibly on ship hulls, oysters, in ballast water). Long-range dispersal of seaweeds does exist, but it is an exception rather than the rule. If it were the rule, the world’s seaweed floras would show similar latitudinal gradients in species composition in the oceans and on both hemispheres. This is, however, not the case.     

Occurrence of fungi on submerged pine and teak blocks in Hong Kong coastal waters

An investigation of the lignicolous marine fungi in Hong Kong coastal waters was carried out for 18 months in order to determine successional patterns of fungal occurrence. Submerged blocks of pine (Pinus massoniana Lambert) and teak (Tectona grandis Linnaeus) were used as baits and were scraped at intervals to remove surface fouling organisms. Occurrence of fungi is described in terms of the composition of the fungal flora and the number of fungal colonies developed on the test blocks before and after incubation. The scraped teak and pine blocks supported slightly different fungal floras, and the selective effect of these substrates on fungal colonization is discussed.     

Late Silurian plant microfossil assemblage from Guangyuan,Sichuan, China

A dispersed plant microfossil assemblage is described from Late Silurian deposits from Guangyuan, Sichuan, China. These strata are interpreted as nearshore, shallow marine deposits, and brachiopods suggest a late Ludlow–early Pridoli age. The palynomorph assemblage is dominated by terrestrial forms, including cryptospores and trilete spores, tubular structures and cuticle-like sheets, although rare marine acritarchs are also present. This microfossil assemblage is comparable to coeval assemblages from around the world (South and Southwest Wales; Libya; Canada; Southeastern Turkey; Northwest Spain; and Jiangsu, China). The sporomorphs from this assemblage indicate the existence of early land plants during the late Ludlow–early Pridoli in Guangyuan, Sichuan, China; and suggests that floras of this age were cosmopolitan and exhibited little palaeogeographical differentiation.     

Local treatment with the selective IκB kinase β inhibitor NEMO-binding domain peptide ameliorates synovial inflammation

Nuclear factor (NF)-κB is a key regulator of synovial inflammation. We investigated the effect of local NF-κB inhibition in rat adjuvant arthritis (AA), using the specific IκB kinase (IKK)-β blocking NF-κB essential modulator-binding domain (NBD) peptide. The effects of the NBD peptide on human fibroblast-like synoviocytes (FLS) and macrophages, as well as rheumatoid arthritis (RA) whole-tissue biopsies, were also evaluated. First, we investigated the effects of the NBD peptide on RA FLS in vitro. Subsequently, NBD peptides were administered intra-articularly into the right ankle joint of rats at the onset of disease. The severity of arthritis was monitored over time, rats were sacrificed on day 20, and tissue specimens were collected for routine histology and x-rays of the ankle joints. Human macrophages or RA synovial tissues were cultured ex vivo in the presence or absence of NBD peptides, and cytokine production was measured in the supernatant by enzyme-linked immunosorbent assay. The NBD peptide blocked interleukin (IL)-1-β-induced IκBα phosphorylation and IL-6 production in RA FLS. Intra-articular injection of the NBD peptide led to significantly reduced severity of arthritis (p < 0.0001) and reduced radiological damage (p = 0.04). This was associated with decreased synovial cellularity and reduced expression of tumor necrosis factor (TNF)-α and IL-1-β in the synovium. Incubation of human macrophages with NBD peptides resulted in 50% inhibition of IL-1-β-induced TNF-α production in the supernatant (p < 0.01). In addition, the NBD peptide decreased TNF-α-induced IL-6 production by human RA synovial tissue biopsies by approximately 42% (p < 0.01). Specific NF-κB blockade using a small peptide inhibitor of IKK-β has anti-inflammatory effects in AA and human RA synovial tissue as well as in two important cell types in the pathogenesis of RA: macrophages and FLS. These results indicate that IKK-β-targeted NF-κB blockade using the NBD peptide could offer a new approach for the local treatment of arthritis.     

THE PENNSYLVANIAN-PERMIAN VEGETATIONAL TRANSITION: A TERRESTRIAL ANALOGUE TO THE ONSHORE-OFFSHORE HYPOTHESIS

An analysis of 68 floras from the Pennsylvanian and Early Permian of Euramerica reveals distinct patterns of environmental distribution. Wetland assemblages are the most commonly encountered floras from the Early and Middle Pennsylvanian. Floras from drier habitats characterize the Permian. Both wetland and dry-site floras occur in the Late Pennsylvanian, but floristic overlap is minimal, which implies strong environmental controls on the distributions of the component species. Drier habitats appear to be the sites of first appearance of orders that become prominent during the Late Permian and Mesozoic. Higher taxa originated in physically heterogeneous, drier habitats, which were geographically marginal throughout most of the Pennsylvanian. They then moved into the lowlands during periods of climatic drying in the Permian, replacing older wetland vegetation. This pattern is analogous to the marine onshore-offshore pattern of origination and migration. The derivation of Mesozoic wetland clades from the Permian dry-lowland vegetation completes the parallel. The similarities of the marine and terrestrial patterns suggest that the combination of evolutionary opportunity, created by physical heterogeneity of the environment, and migrational opportunity, created by changing extrinsic conditions, may be underlying factors that transcend the specifics of organism and environment.