Concerted evolution of the cow epsilon 2 and epsilon 4 beta-globin genes

The nucleotide sequences of the cow epsilon 2 and epsilon 4 globin genes were determined. The sequences were 95% identical. These genes arose via a four-gene block duplication that also gave rise to the bovine fetal (gamma) and adult (beta) genes. Their deduced amino acid sequences are unlike any previously reported fetal or adult globins; rather, comparison to other mammalian globin genes indicates that they are embryonic in nature. The sequence data indicate that these two genes have converted each other during evolution. Pairwise comparison to the corresponding goat genes shows greater similarity between paralogues than between more directly related orthologues. This is in direct contrast to the situation between the cow and goat fetal and adult genes. These observations suggest that the frequency of DNA conversion or the fixation of conversion events may vary in different locations of the cow beta-globin cluster.      

A seasonal study of phosphorus deficiency in a eutrophic reservoir

• 1 Seston elemental composition (C, N, P) and the orthophosphate uptake rate constant, k(upt), were measured in the epilimnion of the eutrophic ?ímov Reservoir in the period March-August 1989.
• 2 Seasonal series of log C/P, log N/P and log [k(upt)] values were highly correlated (r² in the range 0.84–0.93), but, based on literature-derived criteria, k(upt) values indicated stronger P deficiency than did the C/P values.
• 3 The results showed moderate to strong phosphorus deficiency in summer, moderate deficiency at the end of the spring peak of phytoplankton, and no deficiency early in the spring or during the spring clear-water period.

     

Synthesis of α-<Emphasis Type="SmallCaps">D</Emphasis>-Glucose 1,6-Diphosphate in Potentially Prebiotic Conditions

A NOVEL method for the phosphorylation of sugars by orthophosphate in the presence of cyanogen in dilute aqueous neutral or slightly alkaline solutions has been described, suggesting a plausible model of the prebiotic phosphorylation of sugars^1–3. This reaction has now been applied to the synthesis of glucose 1,6-diphosphate, starting either from α-D-glucose 1-phosphate or from D-glucose 6-phosphate. The formation of α-D-glucose 1,6-diphosphate from α-D-glucose 1-phosphate would indicate a possible route for the synthesis of this compound on the primitive Earth. It is known that α-D-glucose 1,6-diphosphate is the coenzyme in the inter-conversion of α-D-glucose 1-phosphate with glucose 6-phosphate catalysed by phosphoglucomutase*. The formation of α-D-glucose 1,6-diphosphate seems to be interesting in view of our model for the chemical evolution of the metabolism of sugars⁵, as it may connect α-D-glucose 1-phosphate with the glycolytic pathway.     

Effect of sub-optimal root zone temperatures at varied nutrient supply and shoot meristem temperature on growth and nutrient concentrations in maize seedlings (Zea mays L.)

Maize seedlings were grown for 10 to 20 days in either nutrient solution or in soils with or without fertilizer supply. Air temperature was kept uniform for all treatments, while root zone temperature (RZT) was varied between 12 and 24°C. In some treatments the basal part of the shoot (with apical shoot meristem and zone of leaf elongation) was lifted up to separate the indirect effects of root zone temperature on shoot growth from the direct effects of temperature on the shoot meristem.Shoot and root growth were decreased by low RZT to a similar extent irrespective of the growth medium (i.e. nutrient solution, fertilized or unfertilized soil). In all culture media Ca concentration was similar or even higher in plants grown at 12 as compared to 24°. At lower RZT concentrations of N, P and K in the shoot dry matter decreased in unfertilized soil, whereas in nutrient solution and fertilized soil only the K concentration decreased.When direct temperature effects on the shoot meristem were reduced by lifting the basal part of the shoot above the temperature-controlled root zone, shoot growth at low RZT was significantly increased in nutrient solution and fertilized soil, but not in unfertilized soil. In fertilized soil and nutrient solution at low RZT the uptake of K increased to a similar extent as plant growth, and thus shoot K concentration was not reduced by increasing shoot growth rates. In contrast, uptake of N and P was not increased, resulting in significantly decreased shoot concentrations.It is concluded that shoot growth at suboptimal RZT was limited both by a direct temperature effect on shoot activity and by a reduced nutrient supply through the roots. Nutrient concentrations in the shoot tissue at low RZT were not only influenced by availability in the substrate and dilution by growth, but also by the internal demand for growth.     

Relation between temporal persistence of host plants and wing length in leafhoppers (Hemiptera: Auchenorrhyncha)

Abstract.

• 1 Wing form frequencies in 255 populations of 101 species of leafhoppers (Auchenorrhyncha) in temporary and permanent habitats were documented.
• 2 The proportion of brachypterous specimens in the leafhopper assemblages on ruderal host plants in temporary habitats (median 2%, range 0–8%) was significantly lower than that on permanent host plants in undisturbed habitats (median 22%, range 0–94%).
• 3 Leafhopper species typical of temporary habitats were either monomorphic, macropterous, or wing-dimorphic with macropterous forms prevailing in both sexes.
• 4 Among the eighty-nine species recorded in permanent habitats, forty-five species were wing dimorphic. In forty-one dimorphic species, a brachypterous form prevailed. This prevalence was found for both sexes in thirty-one species, for only females in nine species and for only males in one species.
• 5 The prevalence of brachypters in males, but not in females, found in Anoscopus flavostriatus, is probably the first such documented case in Auchenorrhyncha.
• 6 The hypothesis is proposed that in temporary habitats, density-dependent production of macropters in wing dimorphic species is an adaptation to frequent habitat deterioration caused by factors independent of the density of the species.
• 7 The predominance of brachypters in permanent habitats indicates that a density-dependent decrease in fitness usually does not offset the potential decrease in fitness connected with macroptery and dispersal. Because of this inability of leafhopper populations to decrease significantly the quality of their resources, a high population density cannot be used as a predictor of future quality of these resources, which is information essential for efficient dispersal behaviour.

     

MICROINJECTION OF TOAD SPERM INTO OOCYTES UNDERGOING MATURATION DIVISION*

Spermatozoa of Bufo bufo japonicus were briefly treated with Triton X-100 to remove their plasma membrane, and were injected into oocytes at various stages of maturation division. All the sperm injected into mature coelomic eggs transformed into pronuclei and synthesized DNA, as a normally fertilizing sperm does. The sperm injected into oocytes at the germinal vesicle (GV) stage did not show any change as long as the GV remained intact. In the oocytes which were induced to mature by progesterone, the injected sperm displayed characteristic features in synchrony with those of the resident female nucleus. These included the formation of several sperm-derived chromosomes in association with multipolar spindles in the oocytes from the stage of the germinal vesicle breakdown to the first polar spindle; the appearance of swollen, vesicular nuclei without concomitant DNA synthesis in those at the stage of the first polar body emission; and the reappearance of the condensed chromosomes with giant spindles in those at the stage of the second meiotic metaphase. Pricking of these last oocytes induced the formation of several male pronuclei and DNA synthesis. These results prove that the injection of detergent-treated sperm employed here provides an excellent means of studying the cytoplasmic state that regulates nuclear behavior.     

Seed Morphology, Anatomy and Ultrastructure ofPhyllocladusL. C. & A. Rich. ex Mirb. (Phyllocladaceae (Pilg.) Bessey) in Connection with the Generic System and Phylogeny

To analyse the status and phylogeny of the genusPhyllocladus,seedsof all seven species of the genus were studied. The complexof features of thePhyllocladusreproductive system point to theisolated position of the genus within the conifers. Relationswith Podocarpaceae s. l., Taxaceae s. l. and Cephalotaxaceaeappeared to be remote because a complex of features clearlydistinguishesPhyllocladusfrom the afore-mentioned taxa. We findit advisable to circumscribe the family Phyllocladaceae as Bessey(1907) did, and place it into the order Taxales Knobl. in Warming(1890). From investigations of the seeds it appears the genusPhyllocladusconsistsof seven species, forming five groups. There is a significanttendency for transformation of the female reproductive structureswithin the generic boundaries ofPhyllocladus—seeds, originallysolitary, tending to aggregate in various kinds of compact clusters.Copyright1999 Annals of Botany Company PhyllocladusL. C. & A. Rich, ex Mirb., seed anatomy, seed morphology, systematics, phylogenetic relationships, Phyllocladaceae, Podocarpaceae s. str., Acmopyleaceae, Nageiaceae, Austrotaxaceae, Amentotaxaceae, Torreyaceae, Taxaceae, s. str., Cephalotaxaceae, Taxales.     

The kinase activity of PKR represses inflammasome activity

The protein kinase R (PKR) functions in the antiviral response by controlling protein translation and inflammatory cell signaling pathways. We generated a transgenic, knock-in mouse in which the endogenous PKR is expressed with a point mutation that ablates its kinase activity. This novel animal allows us to probe the kinase-dependent and -independent functions of PKR. We used this animal together with a previously generated transgenic mouse that is ablated for PKR expression to determine the role of PKR in regulating the activity of the cryopyrin inflammasome. Our data demonstrate that, in contradiction to earlier reports, PKR represses cryopyrin inflammasome activity. We demonstrate that this control is mediated through the established function of PKR to inhibit protein translation of constituents of the inflammasome to prevent initial priming during innate immune signaling. These findings identify an important role for PKR to dampen inflammation during the innate immune response and caution against the previously proposed therapeutic strategy to inhibit PKR to treat inflammation.