Phylogenetic analyses of primate size evolution: the consequences of sexual selection

We have analysed the relationship between primate mating system, size and size dimorphism by utilizing several phylogenetically based methods. An independent contrast analysis of male and female size (log weight) showed that these are tightly correlated and that size dimorphism is not a simple allometric function of size. We found no relationship between mating system and sexual dimorphism in strepsirhines but a strong relationship in haplorhines. By matched-pairs analysis, where sister groups were matched according to whether the mating system predicted higher or lower intrasexual selection for male size, haplorhine species in more polygynous clades (with a predicted higher sexual selection) were significantly more dimorphic, had larger males, and also, but to a lesser degree, larger females. Both independent contrast and matched-pairs analyses are non-directional and correlational. By using a directional test we investigated how a transition in mating system affects size and dimorphism. Here, each observation is the sum of changes in dimorphism or size in a clade that is defined by a common origin of a mating system. Generally, dimorphism, as well as male and female size, increased after an expected increase in sexual selection, and decreased after an expected decrease in sexual selection. The pattern was, however, not significant for all of the alternative character reconstructions. In clades with an expected increase in sexual selection, male size increased more than female size. This pattern was significant for all character reconstructions. The directional investigation indicates that the magnitude of change in haplorhine dimorphism is larger after an increase in sexual selection than after a decrease, and, for some reconstructions, that the magnitude of size increase is larger than the magnitude of size decrease for both sexes. Possible reasons for these patterns are discussed, as well as their implications as being one possible mechanism behind Cope's rule, i.e. general size increase in many phylogenetic lineages.     

Influence of α-interferon therapy on blood lymphoid cells

Summary The influence of natural -interferon (-IFN) therapy (3×10⁶ units i.m. daily) on blood lymphoid cells was studied in 20 patients with gynecological neoplasias (7 patients with condylomata accuminata and 13 patients with ovarian carcinoma). There was a statistically significant increase in the intracellular levels of 2'–5'oligoadenylate synthese 1 day after the first injection of IFN and with few exceptions this activity remained increased during 3 months of treatment. In most of the patients, the capacity of blood lymphoid cells to produce IgA, IgG, and IgM following stimulation with pokeweed mitogen was decreased 1 day after the first injection of IFN and with few exceptions it remained low during 6 months of IFN therapy. In most patients there was a decrease in the capacity of lymphoid cells to act as stimulator or responder cells in a mixed lymphocyte culture during IFN therapy. The -IFN therapy had no major influence on the response of lymphoid cells to mitogens. We conclude, that neither this nor our previous studies on the influence of IFN therapy on immunological functions have given support to the hypothesis that the antitumor action of IFN is mediated by the immune system.     

Covalent modification of phenylalanyl-tRNA synthetase with phenylalanine during the amino acid activation reaction catalyzed by the enzyme

Yeast phenylalanyl-tRNA synthetase (PRS) is shown to undergo autoaminoacylation with phenylalanine under in vitro amino acid activation conditions. Phenylalanyl adenylate enzyme complex yields a covalent phenylalanyl isopeptide exclusively with the beta subunit of the alpha 2 beta 2 enzyme. Contrary to previously reported cases of autoaminoacylation of aspartyl-tRNA synthetase and tryptophanyl-tRNA synthetase, the autoaminoacylation of PRS occurs under a specific set of conditions and results in the identification of only one labeled tryptic peptide on two types of high pressure liquid chromatography columns. The ability of PRS to undergo this covalent modification directly correlates with its ability to catalyze the synthesis of diadenosine 5',5"'-P1,P4-tetraphosphate from enzyme-bound phenylalanyl adenylate. Both reactions require the presence of low levels of zinc or cadmium and are inhibited by tRNAPhe or by low levels of low molecular weight thiols. Since diadenosine 5',5"'-P1,P4-tetraphosphate synthesis is known to be catalyzed in vivo in response to oxidation stress, it is also likely that the autoaminoacylation of phenylalanyl-tRNA synthetase may occur in vivo under a similar set of conditions. These reactions are thus not simply the result of accumulation of phenylalanyl adenylate and probably reflect conformational changes in the protein which are brought about by its interaction with zinc or cadmium.     

Circular dichroism and ordered structure of bisnucleoside oligophosphates and their Zn2+ and Mg2+ complexes

Circular dichroism, absorbance, hypochromicity, and the formation of Mg2+ and Zn2+ complexes have been measured for a series of bisnucleoside oligophosphates that contain adenosine, guanosine, and mixed guanosine/adenosine, guanosine/cytidine, and guanosine/uridine, as well as 7-methylguanosine and ribose-methylated purine nucleosides. All of the metal complex ions have stacking interactions at 2 degrees C, 10 mM tris(hydroxymethyl)aminomethane hydrochloride, pH 8.0. There is a measurable degree of base stacking for all unsubstituted purine nucleotides that differs, however, from that of bases in nucleic acids. The degree of base stacking varies with the length of oligophosphate chains and the state of methylation. The effect of 7-methylation of guanosine is interpreted as causing a switch of nucleic acid base stacking from an atypical to a typical mode, which could be important for cap function in mRNA. The Mg2+ and Zn2+ complexes give rise to characteristic circular dichroism. In all instances excepting 7-methylated bisguanosine oligophosphates, the active secondary structures are disrupted, and in this regard, Zn2+ is more effective than Mg2+. At least two sets of binding sites are involved. A single metal ion is bound tightly. Stability, in terms of equilibrium constants, increases by more than 1000-fold as a function of chain length varying from two to six phosphates. The consequences of methylation are only minor. Electrostatic attraction between metal ions and phosphates is the most likely mechanism of these phenomena as judged by the effect of high ionic strength.     

Inhibition of ATP-regulated K+-channels by a photoactivatable ATP-analogue in mouse pancreatic β-cells

The effects of a photoactivatable (DMNPE-caged) ATP-analogue on ATP-regulated K⁺-channels (K_ATP-channel) in mouse pancreatic β-cells were investigated using the inside-out patch configuration of the patch-clamp technique. The caged precursor caused a concentration-dependent reduction of channel activity with a K_i of 17 μM; similar to the 11 μM obtained for standard Mg-ATP. The small difference in the blocking capacity between the precursor and ATP is probably the reason why no change in channel activity was observed upon photolysis of the caged molecule and liberation of ATP. It is suggested that the part of the ATP molecule involved in the blocking reaction of the K_ATP-channel is not sufficiently protected in DMNPE-caged ATP making this compound unsuitable for studying the rapid kinetics of ATP-induced K_ATP-channel inhibition.     

DIET OF HARBOR PORPOISES IN THE KATTEGAT AND SKAGERRAK SEAS: ACCOUNTING FOR INDIVIDUAL VARIATION AND SAMPLE SIZE

Stomach contents of 112 bycaught harbor porpoises ( Phocoena phocoena ) collected between 1989 and 1996 in the Kattegat and Skagerrak seas were analyzed to describe diet composition and estimate prey size, to examine sample size requirements, and to compare juvenile and adult diets. Although porpoises preyed on a variety of species, only a few contributed substantially to the diet. Atlantic herring ( Clupea harengus ) was the dominating prey species for both juveniles and adults. Our results, in combination with those from previous studies, suggest that where herring is a dominant food source, porpoises prey primarily on size classes containing mature or maturing individuals. Further, we also show that Atlantic hagfish ( Myxine glutinosa ) may be an important food resource, at least for adult porpoises. Examination of sample size requirement showed that, depending on the taxonomic level used to describe the diet, a minimum of 35–71 stomachs are needed to be confident that all common prey species will be found.     

Defective regulation of the cytosolic Ca2+ activity in parathyroid cells from patients with hyperparathyroidism

The parathyroid hormone (PTH) release and cytosolic Ca²⁺ activity were determined in normal bovine parathyroid cells and parathyroid cells obtained from patients with hyperparathyroidism (HPT). There was a sigmoid relation between the cytosolic Ca²⁺ activity and the extracellular calcium concentration between 0.5 and 6.0 mmol/l. The PTH release was inhibited in parallel with the rise in the cytosolic Ca²⁺ activity. Both the hormone release and the cytosolic Ca²⁺ activity were lower in cells from human adenomas and hyperplastic glands~ and in comparison with the bovine preparations these ceils had higher set points for the cytosolic Ca²⁺ activity and PTH release. There was a close correlation between the individual set points for the cytosolic Ca²⁺ activity and PTH release in a material containing both normal and pathological cells. The results indicate that the abnormal PTH release characteristic of HPT is due to a defective regulation of the cytosolic Ca²⁺ activity.     

Prostaglandin I2 stimulation of granulosa cell cyclic AMP production

The ability of prostaglandin I₂ (PGI₂) to stimulate cyclic AMP production by granulosa cells, isolated from intact immature rats, has been demonstrated in vitro. The minimal effective dose was 15 ng/ml, which was comparable to the minimal effective dose for PGE₂. However, a concentration of 15 μg/ml PGI₂ was required to stimulate cyclic AMP production maximally, compared to a concentration of 1 μg/ml PGE₂, which produced the maximum response. It therefore appears that PGI₂ is not more effective than PGE₂ in stimulating cyclic AMP production in granulosa cells, and is possibly less effective. Submaximal concentrations of PGI₂ appeared to be able to modify the stimulation of cyclic AMP production by follicle- stimulating hormone (FSH), but whether or not PGI₂ plays any role in follicular function remains to be established.