Early mouse neural stem cells (NSCs) first appear in embryonic day E5.5 and express pluripotency markers Oct4, Sox2, Nanog and early neural marker Sox1. Early NSCs are a good model for understanding the role of various pathways that control initial neural commitment. However, a protocol for differentiation of mouse embryonic stem cells (ESCs) into early NSCs by adherent monolayer culture has not yet been established. Hence, in this study, we identified the combination of growth factors and small molecules that differentiated mouse ESCs into early NSCs and supported their proliferation. Leukaemia inhibitory factor (LIF) was the first factor to be tested and it was found that ESCs can differentiate into early neurogenic lineage in the presence of LIF. However, we found that the induction is weaker in the presence of LIF as compared to cells differentiated in its absence. GSK-3 inhibitor, along with BMP and TGF-β pathway inhibitor (dual SMAD inhibition), are commonly used to sequentially direct ESCs towards NSCs. However, when we used this combination, mouse ESCs failed to differentiate into early NSCs. We observed that by adding Wnt inhibitor to the combination of GSK-3 inhibitor, BMP inhibitor, TGF-β inhibitor and LIF, it was possible to differentiate ESCs into early NSCs. qRT-PCR analysis of early NSCs illustrated that they expressed key pluripotency genes Oct4 and Nanog, albeit at levels lower than non-differentiated ESCs, along with early neural markers Sox1 and Pax6.
Cílem referátu je připomenout často opomíjenou skutečnost, že grupová rychlost elektromagnetického pulsu v disperzním prostředí může být abnormální, tzn. může převyšovat rychlost světla ve vakuu anebo být záporná. Popíšeme nedávno provedené experimenty, ve kterých byla dosud nejprůkazněji prokázána anbnormální grupová rychlost, a vysvětlíme, proč to neodporuje relativistické příčinnosti., Vladimír Dvořák., and Obsahuje seznam literatury
Temperature dependence of photosynthate partitioning in intact leaf tissue of tomato {Lycopersicon esculentum Milí. cv. Abunda) was studied by using a temperature gradient cuvette systém. At the low photon flux density (PFD, 85 pmol m*2 s**) and saturated CO2 concentration, the total saccharides production was similar over the temperature range from 14 to 30 «€. The starch foímation decreased with decreasing temperature. Formation of the soluble saccharides was affected by the temperature only slightly. This differential effect of the temperature resulted in an increase of the soluble saccharides/starch ratio in tomato leaves under chilling conditions.
Unlike mulberry (Morus alba, M.a.), paper mulberry (Broussonetia papyrifera, B.p.) can acclimate to Karst soil and incline to alien invasion. The photosynthetic parameters, diurnal changes of carbonic anhydrase, and chlorophyll fluorescence induction, and water potential were measured on sunny days (SD) and cloudy days (CD). Photosynthetic midday depression occurred in B.p. but not in M.a. The irradiance-and CO2-saturated photosynthetic rates of B.p. were significantly higher than those of M.a. There was no significant difference in water use efficiency between the two species on a SD. The maximum fluorescence, maximum quantum yield, photochemical quenching, and relative electron transport rate in the leaves of B.p. were much higher than those in M.a. The activity of carbonic anhydrase (CA) of B.p., on either an SD or a CD, was much greater than that of M.a. Higher transpiration rate (E) and net photosynthetic rate (PN) of B.p. resulted in the lack of water in mesophyll cells. Although a higher CA activity of B.p. supplied both water and CO2 for the photosynthesis of mesophyll cells, water in mesophyll cells was the factor limiting photosynthesis, and the intercellular CO2 concentration of B.p. was high and stable. and Y.-Y. Wu ... [et al.].
In Britain, grey squirrels (Sciurus curolinensis Gmelin) and pheasants (Phasianus colchicus Linnaeus) are important hosts of larvae and nymphs of Ixodes ricinus L., the principal F.uropean vector of the Lyme disease spirochaete, Borrelia burgdorferi sensu lalo, T о test whether squirrels are competent hosts of B. burgdorferi s. I., three females were trapped in the wild and then held in captivity. Following treatment, each animal was exposed to uninfected xenodiagnostic I. ricinus ticks. Squirrel A (an adult) which was inoculated experimentally with B. burgdorferi s.l., transmitted the infection to xenodiagnostic ticks. In contrast, squirrel В (a juvenile that was not inoculated)-showed no evidence of infection. Xenodiagnostic ticks that fed on control squirrel С (an adult) became infected and subsequently transmitted the infection experimentally to an uninfected hamster. The results indicated that squirrel С had a disseminated infection acquired in the wild and which persisted for at least 11 weeks. These data clearly demonstrate that grey squirrels are amplifying and reservoir hosts of B. burgdorferi s.l. The strain associated with squirrels was related to the B. afzelii genotype. Two observations implicated pheasants in a similar role; (i) a high prevalence of infection in engorged larvae collected from trapped pheasants, and (ii) the detection of B. burgdorferi s.l. (В. garinii genotype) in the wattle of 1/10 pheasants using PCR. Xenodiagnostic experiments similar to those undertaken with the squirrels are needed to confirm the role of pheasants in the transmission cycle of Lyme disease spirochaetes.
The seasonal activities of the European pigeon tick, Argas reflexus, in Berlin were investigated (a) by trapping locomotory active ticks and (b) by determining the occurrence of tick-invasions into human habitations. Tick trapping was carried out in two tick-infested attics in 1988. Pigeons were available for ticks in one of the attics only, while a previously existing bird colony was expelled from the other. Ticks were trapped by means of smooth V- shaped metal gutters cemented to the attic walls. Trapped nymphal and adult ticks were marked and released into cracks of the attic wall inside the rectangular traps in two-weck-intervals. During the one-year-study a total of 2081 ticks was trapped, 83% of which were larvae, 10% nymphs, 4% females and 3% males. Only 4.4% of the 366 ticks marked were recaptured. There is strong evidence that locomotor activities of A. reflexus were restricted to host-seeking and returning to a resting-site after a blood meal. Activities of all postembryonic stages peaked from March through early June, irrespective of whether or not hosts were available to the ticks. The immature stages displayed another peak of activity in late summer/autumn. A total of 51 cases of A. reflexus-infested buildings was reported from the public to public-health offices in Berlin from April 1989 to March 1993, 45 of which represented tick invasions into human habitations. About 60% of them occurred in spring, thus largely confirming the results of seasonal trapping.
In the present paper we consider algebras satisfying both the congruence extension property (briefly the CEP) and the weak congruence intersection property (WCIP for short). We prove that subalgebras of such algebras have these properties. We deduce that a lattice has the CEP and the WCIP if and only if it is a two-element chain. We also show that the class of all congruence modular algebras with the WCIP is closed under the formation of homomorphic images.