Leaf canopy plays a determining role influencing source-sink relations as any change in source activity (photosynthesis) affects sink metabolism. Defoliation (removal of leaves) influences growth and photosynthetic capacity of plants, remobilizes carbon and nitrogen reserves and accelerates sink metabolism, leading to improved source-sink relations. The response of plants to defoliation could be used to manipulate source-sink relations by removing lower and senescing leaves to obtain greatest photosynthetic capacity and efficient carbon and nitrogen metabolism under optimal and stressful environments. The present work enhances our current understanding on the physiological responses of plants to defoliation and elaborates how defoliation influences growth, photosynthetic capacity and source-sink relations under optimal and changing environmental conditions., N. Iqbal, A. Masood, and N. A. Khan., and Obsahuje bibliografii
A new species of amphizoic amoeba, Nuclearia pattersoni sp. n., isolated from gills of Rutilus rutilus L. is described. It is characterised by elongate flattened trophozoites of irregular shape. The longer dimension of their bodies is 13.2 (11.0-15.7) µm. Filopodia radiating mostly from the poles are 2 to 2.5 times longer than the body. The diameter of less frequently observed spherical trophozoites is 8.2-10.8 µm; their filopodia radiate to all directions. Cyst-like stages have shorter pseudopodia that arise from one pole only. The surface of locomotive forms from agar plate cultures has a thin amorphous glycocalyx, while most cells are covered by two layers of extracellular matrix. Mitochondria have flattened cristae, dictyosomes are located in the perinuclear zone. A conspicuous ultrastructural feature of the morphologically similar N. simplex, perinuclear striated band, is not present. Light microscopic and ultrastructural data are completed with the sequence of SSU rRNA gene and phylogenetic analysis including sequences of related taxa. The bacterial endosymbiont found in N. pattersoni type strain RR2G2 is assigned to the genus Rickettsia.
One of the main aims of the present and the next part [15] is to show that the theory of graphs (its language and results) can be very useful in algebraic investigations. We characterize, in terms of isomorphisms of some digraphs, all pairs A, L, where A is a finite unary algebra and L a finite lattice such that the subalgebra lattice of A is isomorphic to L. Moreover, we find necessary and sufficient conditions for two arbitrary finite unary algebras to have isomorphic subalgebra lattices. We solve these two problems in the more general case of partial unary algebras. In the next part [15] we will use these results to describe connections between various kinds of lattices of (partial) subalgebras of a finite unary algebra.
We review the basic features of oscillations observed at different height levels in the sunspot atmosphere, moreover, various possibilities for a theoretical interpretation are discussed. In the umbra oscillation power is concentrated in severa] period bands
(3 min., 5 min., and ≥ 20 min.) which on their part are composed of closely packed peaks. The observed amplitudes and phases of velocity and of intensity oscillations depend in a characteristic way on the period and on the height. These features are used to look for the most probable physical mechanisms which could produce the different modes: At subphotospheric depths two independent resonators are acting. A resonator for slow, quasi-transveree waves can explain the lifetimes of umbral dots (≥ 20 min.), while a resonator for fast (acoustic), quasi-longitudinal waves could result in the umbral 5-min. oscillations. The acoustic resonator strongly couples with the slow-mode longitudinal resonator at photospheric and chromospheric heights, the latter produces the resonance peaks in the 3-min. band. Running penumbral waves can be explained by the transformation of 5-min, waves from the convective zone in the almost horizontal magnetic field. The interpretation of oscillations provides a new method of probing not only subphotospheric, but also atmospheric layers of sunspots (e.g., of determining temperature gradients), thus completing customary spectroscopic diagnostics.
Flounder, Paralichthys orbignyanus (Valenciennes), were captured in polluted and non-polluted sites within the Patos Lagoon Estuary, southern Brazil, over four seasons. Blood films showed a high prevalence of infection with a haemogregarine, or mixed parasitaemias of this and an organism resembling Haemohormidium terraenovae So, 1972. Haemogregarine gamont stages conformed to existing descriptions of Desseria platessae (Lebailly, 1904) Siddall, 1995 from flatfishes, but intraerythrocytic division of meronts was observed, leading to the recommendation for nomenclatural correction, placing the haemogregarine in the genus Haemogregarina (sensu lato) Danilewsky, 1885. Statistical analyses suggested that although sample sizes were small, infections with meront stages, immature and mature gamonts were all influenced by site, and possibly therefore, by pollution. Season also appeared to determine likelihood of infection with meronts and immature gamonts, but not mature gamonts, while adult fish gender apparently affected infection with immature and mature gamonts, but not meronts. The H. terraenovae-like organism exhibited unusual extracellular forms and did not match closely with the type description of H. terraenovae; precise identification was therefore difficult. Data analyses suggested that parasitism by this organism was influenced by site and fish gender, since females and males from non-polluted water were infected, but only females from the polluted site. Season was also important and significantly more adult fish of both sexes were infected with this parasite in the Brazilian summer and autumn, compared with winter and spring. Finally, these appeared to be the first observations of Haemogregarina platessae, and possibly H. terraenovae, from the southern hemisphere.
The extracellular matrix (ECM) consists of proteins,
glycosaminoglycans and glycoproteins, that support the dynamic
interactions between cells, including intercellular communication,
cell attachment, cell differentiation, cell growth and migration. As
such, the ECM represents an essential and very sensitive system
within the tissue microenvironment that is involved in processes
such as tissue regeneration and carcinogenesis. The aim of the
present review is to evaluate its diversity through Ca2+ signaling
and its role in muscle cell function. Here, we discuss some
methodological approaches dissecting Ca2+ handling mechanisms
in myogenic and non-myogenic cells, e.g. the importance of Ca2+
and calpains in muscle dystrophy. We also consider the
reconstruction of skeletal muscle by colonization of decellularized
ECM with muscle-derived cells isolated from skeletal muscle.
Therefore, it is necessary to establish new methodological
procedures based on Ca2+ signaling in skeletal muscle cells and
their effect on ECM homeostasis, allowing the monitoring of
skeletal muscle reconstruction and organ repair.