This study investigated the synthesis of
Xenopus
histones during erythropoiesis. Although cessation of DNA replication in the mid‐stages of erythroid maturation is accompanied by arrested synthesis ...of histone H1 and core histones, synthesis of H1
s
(an H1°‐like histone) was found to continue into late stages of erythropoiesis, as has been reported for avian erythrocyte histone H5. This was accompanied by a threefold increase in the relative amount of
Xenopus
H1
s
, similar to the accumulation reported for H5 during avian erythropoiesis and for H1° in some differentiated mammalian cells. The structural and metabolic homologies of avian H5, mammalian H1°, and
Xenopus
H1
s
imply that these lysine‐rich histones have closely related functions distinct from those of H1, and thus represent a subclass of lysine‐rich histones.
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A&A, 354, L41 The calculation of accurate collision strengths for atomic transitions has
been a long standing problem in quantitative spectroscopy. Most modern
calculations are based on the R-matrix ...method and problems pertaining to the
use of this method have led to a discussion of the accuracy of these results.
More in particular, based on an analysis of the spectra of NGC 3918 and NGC
6302, Clegg et al. (1987) and Oliva et al. (1996) have questioned R-matrix
calculations for the infrared Ne V fine-structure transitions. Using improved
flux measurements for the Ne V lines, we show that the conclusion that these
collision strengths would be too high, is not correct. The discrepancies found
by Clegg et al. (1987) can be explained by the inaccuracy of the Ne V 342.6
nm flux they adopted. The discrepancies found by Oliva et al. (1996) can be
explained by the inaccuracy of the LRS flux for the Ne V 14.32 micron line.
Based on the data presented in this paper there is no reason to assume that
there are any problems with the R-matrix calculations for Ne^4+ of Lennon &
Burke (1994). We show that the data are accurate at the 30 % level or better.
This confirms the validity of the close coupling method.
STUDIES ON THE DENATURATION OF ANTIBODY Wright, George G.; Schomaker, Verner
The Journal of biological chemistry,
08/1948, Volume:
175, Issue:
1
Journal Article
Peer reviewed
Open access
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Interleukin 2 (IL2) is a lymphokine which stimulates the growth of T lymphocytes. Although IL2 mRNA is translated into biologically active IL2 relatively efficiently in microinjected Xenopus laevis ...oocytes, it has been difficult to establish reproducible cell-free translation systems for this lymphokine. Such systems would be useful for the analysis of translational and post-translational events. In this paper, we show that a wheat germ extract will translate IL2 mRNA into biologically active murine IL2, most of which is translocated into dog pancreas microsomes when these are present. Translocation occurs only during translation, but wheat germ extracts translate IL2 mRNA whether microsomes are present or not. Surprisingly, reticulocyte lysates do not readily translate IL2 mRNA, and strongly inhibit its translation in wheat germ extracts. This inhibition can be partially alleviated by adding dog pancreas microsomes to the system. The inhibition seen with reticulocyte lysate may be attributable to the action of the signal recognition particle, which binds nascent secretory proteins, and blocks their further translation in the absence of the docking protein present in microsomes.
The consumption of a number of agricultural products varies from one season of the year to another. For some products, seasonal variations in consumption correspond to variations in production. For ...others, such as fluid milk, consumption and production patterns tend to vary inversely, Downen 2 reported significant seasonal variations in daily average sales of fluid milk with the highest sales occurring in the fall and winter months and the lowest in the spring and summer months. Other studies 1,5 have also reported seasonal variations in per capita sales of fluid milk. Conversely, production of fluid milk naturally tends to peak in the spring and summer months and reach its lowest point in the fall and winter.
The problem of determining simultaneously the flows of primary products through processors to the market as final products has been formulated alternatively as a transhipment model by King and Logan ...and as a reduced matrices model by Rhody. An extension of this problem to a multiregion, multiproduct, and multiplant problem formulated in the general linear programming framework has been proposed by Judge et al. This article presents some alternative formulations of the problem within the framework of the transportation model that permit solution of problems of the type discussed by King and Logan without the need for subtraction of artificial variables; solution of problems of the transhipment type where processing capacity in any one or all of the regions is limited, but where the total processing capacity of all regions is enough or more than enough to handle the supply of the raw product; and solution of multiregion, multiplant, multiprocessing, and multiproduct problems of the type discussed by Judge.
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High-resolution N-body simulations are used to investigate systematic trends
in the mass profiles and total masses of clusters as derived from 3 simple
estimators: (1) the weak gravitational lensing ...shear field under the assumption
of an isothermal cluster potential, (2) the dynamical mass obtained from the
measured velocity dispersion under the assumption of an isothermal cluster
potential, and (3) the classical virial estimator. The clusters consist of
order 2.5e+05 particles of mass $m_p \simeq 10^{10} \Msun$, have triaxial mass
distributions, and significant substructure exists within their virial radii.
Not surprisingly, the level of agreement between the mass profiles obtained
from the various estimators and the actual mass profiles is found to be
scale-dependent.
The virial estimator yields a good measurement of the total cluster mass,
though it is systematically underestimated by of order 10%. This result
suggests that, at least in the limit of ideal data, the virial estimator is
quite robust to deviations from pure spherical symmetry and the presence of
substructure. The dynamical mass estimate based upon a measurement of the
cluster velocity dispersion and an assumption of an isothermal potential yields
a poor measurement of the total mass. The weak lensing estimate yields a very
good measurement of the total mass, provided the mean shear used to determine
the equivalent cluster velocity dispersion is computed from an average of the
lensing signal over the entire cluster (i.e. the mean shear is computed
interior to the virial radius). abridged
Recent data from an experimental plantation of Picea abies Karst., including selfed and open‐pollinated progenies of four different mother trees are presented. The measurements were made when the ...trees had reached an age of 61 years. Pair‐wise comparisons between selfed and open‐pollinated progenies of different mother trees with respect to tree height, breast‐height diameter, and trunk volume revealed that the selfed progenies suffered severely from inbreeding depression.
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