An Outer Arm Dynein Conformational Switch Is Required for Metachronal Synchrony of Motile Cilia in Planaria

Motile cilia mediate the flow of mucus and other fluids across the surface of specialized epithelia in metazoans. Efficient clearance of peri-ciliary fluids depends on the precise coordination of ciliary beating to produce metachronal waves. The role of individual dynein motors and the mechanical feedback mechanisms required for this process are not well understood. Here we used the ciliated epithelium of the planarian Schmidtea mediterranea to dissect the role of outer arm dynein motors in the metachronal synchrony of motile cilia. We demonstrate that animals that completely lack outer dynein arms display a significant decline in beat frequency and an inability of cilia to coordinate their oscillations and form metachronal waves. Furthermore, lack of a key mechanosensitive regulatory component (LC1) yields a similar phenotype even though outer arms still assemble in the axoneme. The lack of metachrony was not due simply to a decrease in ciliary beat frequency, as reducing this parameter by altering medium viscosity did not affect ciliary coordination. In addition, we did not observe a significant temporal variability in the beat cycle of impaired cilia. We propose that this conformational switch provides a mechanical feedback system within outer arm dynein that is necessary to entrain metachronal synchrony.     

Can the Study of Natural Vegetation Succession Assist in the Control of Soil Erosion on Abandoned Croplands on the Loess Plateau,China?

In the Loess Plateau, China, arable cultivation of slope lands is common and associated with serious soil erosion. Planting trees or grass may control erosion, but planted species may consume more soil water and can threaten long‐term ecosystem sustainability. Natural vegetation succession is an alternative ecological solution to restore degraded land, but there is a time cost, given that the establishment of natural vegetation, adequate to prevent soil erosion, is a longer process than planting. The aims of this study were to identify the environmental factors controlling the type of vegetation established on abandoned cropland and to identify candidate species that might be sown soon after abandonment to accelerate vegetation succession and establishment of natural vegetation to prevent soil erosion. A field survey of thirty‐three 2 × 2–m plots was carried out in July 2003, recording age since abandonment, vegetation cover, and frequency of species together with major environmental and soil variables. Data were analyzed using correspondence analysis, classification tree analysis, and species response curves. Four vegetation types were identified and the data analysis confirmed the importance of time since abandonment, total P, and soil water in controlling the type of vegetation established. Among the dominant species in the three late‐successional vegetation types, the most appropriate candidates for accelerating and directing vegetation succession were King Ranch bluestem (Bothriochloa ischaemum) and Lespedeza davurica (Leguminosae). These species possess combinations of the following characteristics: tolerance of low water and nutrient availability, fibrous root system and strong lateral vegetative spread, and a persistent seed bank.     

Taxonomy and ecology of <Emphasis Type="Italic">Castanea sativa</Emphasis> Mill. forests in Greece

Castanea sativa Mill. is an important species of the Balkan Peninsula with high ecological and economic value. This article contributes to a phytosociological synsystematic approach of the C. sativa plant communities in Greece that covers the southern part of the Balkan Peninsula and describes the ecological parameters involved in their distribution and taxonomy. Phytosociological data have been collected from 14 mountainous areas across continental Greece, which are considered representative of the main forest types of C. sativa in the area. The 14 mountains demonstrate a variety of environmental conditions. Five communities (associations) and seven sub-communities (sub-associations) have been identified and described using TWINSPAN, Corespondence Analysis and the Braun-Blanquet classification scheme. Castanea sativa (chestnut) forests of Greece can be distinguished as three broad groups, defined primarily by their geographical distribution. In northern and central Greece chestnut stands are characterized by their high floristic homogeneity, which is reflected in the identification of only one community per region. Chestnut forests in northern Greece, in particular, exhibit strong floristic similarities with those of the rest of the Balkans. In southern Greece, on the other hand, the southern distribution limit of chestnut in the Balkans, there is a greater floristic diversity between the sampled mountains which is reflected in the presence of three confirmed communities and two sub-associations. Several factors have been identified as important in determining the structure and floristic composition of chestnut forests in Greece. Whilst climate and the grazing regime are influential, the degree of silvicultural management appears to be the most important factor determining the floristic composition of chestnut forests and their long-term sustainability.     

Syntaxonomy and Synecology of <Emphasis Type="Italic">Quercus coccifera</Emphasis> Mediterranean Shrublands in Greece

Quercus coccifera (kermes oak) is the most common species of the Mediterranean maquis with a wide distribution across the Mediterranean Basin. This paper presents a syntaxonomic overview of the Q. coccifera plant communities in the Mediterranean zone of Greece (Quercetea ilicis) based on the classification of 221 relevés from 34 (17 continental and 17 insular) mountainous areas throughout Greece. Two associations and eight sub-associations are described and presented in a synoptic constancy table. Querco cocciferae–Pistacietum lentisci is the most widespread, is found in the entire continental Greece and most islands, and is further subdivided into five sub-associations reflecting primarily local peculiarities in the disturbance regime and the influence of local floristic elements. Rhamno lycioidis–Cocciferetum (Rivas Goday & Rivas-Martínez 1954), on the other hand, is geographically confined on the island of Crete and is further subdivided into three sub-associations, reflecting differences in the annual precipitation, and they are characterized by the presence of many phryganic and grazing-resistant species. Climate and the anthropogenic pressure have been identified to be the most important factors determining the structure and the floristic composition of Q. coccifera Mediterranean shrublands of Greece.     

Resistance to cerebral ischemic injury in UCP2 knockout mice: evidence for a role of UCP2 as a regulator of mitochondrial glutathione levels

Uncoupling protein 2 (UCP2) is suggested to be a regulator of reactive oxygen species production in mitochondria. We performed a detailed study of brain injury, including regional and cellular distribution of UCP2 mRNA, as well as measures of oxidative stress markers following permanent middle cerebral artery occlusion in UCP2 knockout (KO) and wild-type (WT) mice. Three days post ischemia, there was a massive induction of UCP2 mRNA confined to microglia in the peri-infarct area of WT mice. KO mice were less sensitive to ischemia as assessed by reduced brain infarct size, decreased densities of deoxyuridine triphosphate nick end-labelling (TUNEL)-labelled cells in the peri-infact area and lower levels of lipid peroxidation compared with WT mice. This resistance may be related to the substantial increase of basal manganese superoxide dismutase levels in neurons of KO mice. Importantly, we found a specific decrease of mitochondrial glutathione (GSH) levels in UCP2 expressing microglia of WT, but not in KO mice after ischemia. This specific association between UCP2 and mitochondrial GSH levels regulation was further confirmed using lipopolysaccharide models of peripheral inflammation, and in purified peritoneal macrophages. Moreover, our data imply that UCP2 is not directly involved in the regulation of ROS production but acts by regulating mitochondrial GSH levels in microglia.     

Four new depsides in Origanum dictamnus methanol extract

We herein describe the identification of four new depsides present in methanol extract of Origanum dictamnus. O. dictamnus’ (dittany) aerial parts methanol extract was subjected to semi-preparative RP-HPLC fractionation followed by identification of individual compounds in each fraction using 1D/2D NMR, MS approaches and DFT calculations. The structural data revealed that 4 of the compounds were novel hitherto unidentified molecules, whereas the other 6 corresponded to known structures belonging to the groups of monoterpenes, phenolic acids and depsides. We have additionally estimated the antioxidant capacity of the methanol extract and individual fractions using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) in vitro assay. Methanol extract exhibited significant scavenging activity, which was attributed predominantly to the depside group of phytochemicals. The scavenging activity of the new compounds is reported herein for first time. Moreover, the antimitotic activities of the methanol extract as well as that of rosmarinic acid were examined and appeared to be several fold weaker comparing to their scavenging capacity.     

Entrainment of peripheral clock genes by cortisol

Circadian rhythmicity in mammals is primarily driven by the suprachiasmatic nucleus (SCN), often called the central pacemaker, which converts the photic information of light and dark cycles into neuronal and hormonal signals in the periphery of the body. Cells of peripheral tissues respond to these centrally mediated cues by adjusting their molecular function to optimize organism performance. Numerous systemic cues orchestrate peripheral rhythmicity, such as feeding, body temperature, the autonomic nervous system, and hormones. We propose a semimechanistic model for the entrainment of peripheral clock genes by cortisol as a representative entrainer of peripheral cells. This model demonstrates the importance of entrainer's characteristics in terms of the synchronization and entrainment of peripheral clock genes, and predicts the loss of intercellular synchrony when cortisol moves out of its homeostatic amplitude and frequency range, as has been observed clinically in chronic stress and cancer. The model also predicts a dynamic regime of entrainment, when cortisol has a slightly decreased amplitude rhythm, where individual clock genes remain relatively synchronized among themselves but are phase shifted in relation to the entrainer. The model illustrates how the loss of communication between the SCN and peripheral tissues could result in desynchronization of peripheral clocks.     

Bisphosphonate-loaded bone cement: Background,clinical indications and future perspectives

Bisphosphonates represent an established treatment against bone resorption and osseous loss. Local application could help increase bone mineral density while minimizing their systemic use side-effects. Bone cement, used on a large scale in orthopedic surgery and a historically successful drug carrier, could represent an effective scaffold. The aim of this review was to investigate the alterations produced on the cement’s structure and properties by this mixture, as well as its antiosteoporotic and antitumor effect. After a thorough research of articles, title screening and duplicate removal we retained 51 papers. Two independent authors performed abstract and full-text reading, finally leaving 35 articles included in this review. In the current literature, acrylic and calcium phosphate bone cement have been used as carriers. A combination with nitrogen-containing bisphosphonates, e.g., zoledronic acid, provokes modifications in terms of setting time prolongation and mechanical strength decline within acceptable levels, on the condition that the drug’s quantity stays beneath a certain plateau. Bisphosphonates in bone cement seem to have a powerful anti-osteoclastic and osteogenic local impact as well as a direct cytotoxic effect against several neoplastic lesions. Further investigation on the subject is required, with specifically designed studies focusing on this method’s advantages and potential clinical applications.     

The Mutational Spectrum of Lynch Syndrome in Cyprus

Lynch syndrome is the most common form of hereditary colorectal cancer and is caused by germline mutations in the mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2. Mutation carriers have an increased lifetime risk of developing colorectal cancer as well as other extracolonic tumours. The aim of the current study was to evaluate the frequency and distribution of mutations in the MLH1, MSH2 and MSH6 genes within a cohort of Cypriot families that fulfilled the revised Bethesda guidelines. The study cohort included 77 patients who fulfilled at least one of the revised Bethesda guidelines. Mutational analysis revealed the presence of 4 pathogenic mutations, 3 in the MLH1 gene and 1 in the MSH2 gene, in 5 unrelated individuals. It is noted that out of the 4 pathogenic mutations detected, one is novel (c.1610delG in exon 14 of the MLH1) and has been detected for the first time in the Cypriot population. Overall, the pathogenic mutation detection rate in our patient cohort was 7%. This percentage is relatively low but could be explained by the fact that the sole criterion for genetic screening was compliance to the revised Bethesda guidelines. Larger numbers of Lynch syndrome families and screening of the two additional predisposition genes, PMS2 and EPCAM, are needed in order to decipher the full spectrum of mutations associated with Lynch syndrome predisposition in Cyprus.