Search results for "genus"
showing 10 items of 755 documents
Modelling for rearrangement of fusiform initials during radial growth of the vascular cambium in Pinus sylvestris L.
2013
In contrast to common belief, recent studies have confirmed that intrusive growth of fusiform cambial initials has a significant role in the rearrangement of the initials, but does not contribute to the cambial circumference increment. We observed a rapid rearrangement of cambial initials on a long series of transverse sections of the vascular cambium and the wood of a 50-year-old pine (Pinus sylvestris L.) tree. A comparison of cell arrangement in consecutive sections, as well as a critical analysis of tangential reconstructions, has confirmed that changes in cell locations in a group of cells on the tangential surface caused no change in the total tangential width of the whole group. Mode…
Antileishmanial Activity of the Genus Piper: A Systematic Review
2021
Background: Leishmaniases are anthropozoonotic vector-borne diseases, caused by the protozoan Leishmania spp. These diseases have significant morbidity and mortality worldwide and, as there are currently no vaccines available for their treatment, chemotherapy remains the mainstay for anti-leishmanial therapeutics. However, the severe side effects, reduced bioavailability, high cost and chemoresistance, amongst other problems, limit the use of available drugs. In recent years, natural compounds have shown promise as anti-leishmanial agents, especially those extracted from medicinal plants. The genus Piper has been used in traditional medicine and widely explored for its biological properties…
The genus Pleurotus in Italy
2015
On the basis of personal observations, herbarium specimens and, data reported in the literature the authors report morphological, ecological and distributive data on Pleurotus taxa from Italy. New descriptions are here provided based on the most distinctive-discriminating eco-morphological characters of twelve Pleurotus taxa.
A molecular study of Neophyllaphis varicolor (Hemiptera, Aphididae) in Costa Rica
2019
The genus Neophyllaphis (Takahashi) (Aphididae: Neophyllaphidinae) is composed of 18 species; however, in the Americas only nine species have been reported previously. A new species, Neophyllaphis varicolor Miller & Halbert, was described in 2014 in USA. Colonies resembling those of this new species have been observed in Costa Rica on Podocarpus spp. In order to determine if N. varicolor is also present in Costa Rica, we sampled Neophyllaphis colonies from Podocarpus falcatus and P. chinensis. Additionally, we sampled individuals from Podocarpus sp. in Spain and Vietnam. DNA of each sample was extracted and used to amplify and sequence the cytochrome c oxidase subunit I (COI) and elongation…
Developmental morphology of Apinagia multibranchiata (Podostemaceae) from the Venezuelan Guyanas
2000
Abstract Apinagia ( c. 50 spp.) is the largest genus of American Podostemaceae. Apinagia multibranchiata (Matth.) Royen is a haptophyte endemic to the Venezuelan Guyanas. It fits well with the Podostemoideae bauplan known from other New World genera, such as Marathrum and Mourera . Shoots arise in pairs from filamentous creeping adhesive roots. During the rainy season submerged vegetative shoots grow up to more than a metre long. They are normally unbranched and provided with distichously arranged leaves which are laterally flattened into one plane. The lanceolate leaves may show a fimbriate tip. Tufts of threads are found on the upper leaf surface which faces the sky. When the water recede…
A molecular approach to the taxonomy and biogeography of African parrots
2000
Random amplified polymorphic DNA analysis of blood samples from eight African parrot species was performed to study the genetic relationship within the genus Poicephalus and among Poi-cephalus and the two other main African parrot genuses, Agapornis and Psittacus. To this end, DNA from six Poicephalus species, one species, of the Agapornis group and the single Psittacus species was analysed. The amplification pattern was then converted into a binary matrix and scored by the unweighted pair-group method algorithm. The resulting dendrogram showed a neat separation of all the Poicephalus on one side, from Psittacus-Agapornis on the other side. Among the six analysed species of Poicephalus, two…
Presentations for the punctured mapping class groups in terms of Artin groups
1999
Consider an oriented compact surface F of positive genus, possibly with boundary, and a finite set P of punctures in the interior of F, and define the punctured mapping class group of F relatively to P to be the group of isotopy classes of orientation-preserving homeomorphisms h: F-->F which pointwise fix the boundary of F and such that h(P) = P. In this paper, we calculate presentations for all punctured mapping class groups. More precisely, we show that these groups are isomorphic with quotients of Artin groups by some relations involving fundamental elements of parabolic subgroups.
Assessment of the quality of the air in the city of Palermo through chemical and cell analyses on Pinus Needles
2001
The influence of air pollution on the chemical composition of Pinus sp. needles was examined in polluted and control sites in and around the city of Palermo (Sicily). The chemical composition of needles indicated the extent of contamination of the trees, which were cytologically examined. Cell analysis was carried out on pine samples, including needles and pollens, from 15 different locations. Biostructural and spectrophotometric tests were performed. In particular, concentrations of toxic (Cd, Pb) and non-toxic metals (Fe,Cu, Zn) were determined, as well as injury caused by their accumulation in the needles. The more highly urbanised areas showed higher concentrations of metals (Pb, Cu. Zn…
Occurrence of platinum, palladium and gold in pine needles of Pinus pinea L. from the city of Palermo (Italy)
2003
Abstract Preliminary data on the presence of Pt, Pd and Au in airborne particulate matter from the urban area of Palermo (Sicily, Italy) are presented. They were obtained by analysing 40 samples of pine needles (Pinus pinea L.) collected in and around the city. Observed concentrations range from 1 to 102 μg/kg for Pt, 1 to 45 μg/kg for Pd and 22 to 776 μg/kg for Au. Platinum and Pd concentrations in pine needles are up to two orders of magnitude higher than their crustal abundances. They exhibit a high statistical correlation (R2=0.74) which suggests a common origin. Precious metal concentrations measured within the city centre are much higher than those occurring outside the town. The dist…
NOR regions of polychaete worms of the genus Ophryotrocha studied by chromosome banding techniques and FISH.
2000
This article reports the results of cytogenetic analyses carried out on 10 species of polychaete worms belonging to the genus Ophryotrocha (Dorvilleidae). Nucleolar organizer regions (NORs) were characterized by Ag staining, C-banding, CMA3 staining, and ribosomal fluorescent in situ hybridization (rDNA FISH). Extensive intraspecific variation in NOR number and distribution were observed in O. costlowi, O. sp. macrovifera, O. notoglandulata, O.l. labronica, O. l. pacifica (2n = 6), O. p. puerilis, O. diadema (2n = 8), O. hartmanni, O. gracilis (2n = 10). In O. sp. robusta (2n = 10), Ag-NORs were always located on a single chromosome pair. CMA3 staining suggests a possible trend toward a GC-…