HOX cofactors expression and regulation in the human ovary

Background  

HOX cofactors enhance HOX binding affinities and specificities and increase HOX's unique functional activities. The expression and the regulation of HOX cofactors in human ovaries are unknown.     

Time-varying and static magnetic fields act in combination to alter calcium signal transduction in the lymphocyte.

We have tested the hypothesis that extremely low frequency (ELF) time-varying magnetic fields act in combination with static magnetic fields to alter calcium signalling in the lymphocyte. Results indicate that a 60-min exposure of thymic lymphocytes at 37 +/- 0.05 degrees C to a 16 Hz, 421 mG (42.1 microT) magnetic field simultaneously with a colinear static magnetic field of 234 mG (23.4 microT) (a.c./d.c. field intensity ratio = 1.8) inhibits calcium influx triggered by the mitogen Concanavalin A. Significantly, resting lymphocytes do not respond to the fields, thus, only mitogen-activated cells undergoing calcium signalling exhibit a field response. These results indicate that signal transduction involving calcium is an important biological constraint which operates to mediate this field interaction. Additional split field exposures show that the presence of the a.c. field or the d.c. field alone does not produce an effect. This is consistent with a proposed parametric resonance theory of interaction of low intensity magnetic fields with biological systems (L.L. Lednev (1991) Bioelectromagnetics 12, 71-75), which predicts the occurrence of biological effects at specific values for the frequency and field intensity of the ELF and static magnetic fields.     

Multicolor BiFC analysis of competition among G protein β and γ subunit interactions

We have applied multicolor BiFC to study the association preferences of G protein β and γ subunits in living cells. Cells co-express multiple isoforms of β and γ subunits, most of which can form complexes. Although many βγ complexes exhibit similar properties when assayed in reconstituted systems, knockout experiments in vivo suggest that individual isoforms have unique functions. BiFC makes it possible to correlate βγ complex formation with functionality in intact cells by comparing the amounts of fluorescent βγ complexes with their abilities to modulate effector proteins. The relative predominance of specific βγ complexes in vivo is not known. To address this issue, multicolor BiFC can determine the association preferences of β and γ subunits by simultaneously visualizing the two fluorescent complexes formed when β or γ subunits fused to amino terminal fragments of yellow fluorescent protein (YFP-N) and cyan fluorescent protein (CFP-N) compete to interact with limiting amounts of a common γ or β subunit, respectively, fused to a carboxyl terminal fragment of CFP (CFP-C). Multicolor BiFC also makes it possible to determine the roles of interacting proteins in the subcellular targeting of complexes, study the formation of protein complexes that are unstable under isolation conditions, determine the roles of co-expressed proteins in regulating the association preferences of interacting proteins, and visualize dynamic events affecting multiple protein complexes. These approaches can be applied to studying the assembly and functions of a wide variety of protein complexes in the context of a living cell.     

Detection of NAD: arginine ADPribosyltransferases in animal tissues using 125I-labeled 1-(p-hydroxyphenyl) 2-guanidinoethane as ADPribose acceptor

¹²⁵I-labeled 1-(p-hydroxyphenyl) 2-guanidinoethane (N-guanyltyramine), previously used to assay for the bacterial toxin choleragen (Mekalanos, J.J., Collier, R.J. And Romig, W.R. (1979) J. Biol. Chem. 254, 5894-5854) was utilized to identify NAD: arginine ADPribosyltransferases in animal tissues. The use of this radiolabelled ADPribose acceptor, rather than radiolabelled NAD, would bypass the problem posed by the almost ubiquitous presence of enzymes that degrade NAD. With a homogeneous ADPribosyltransferase from turkey erythrocytes, NAD and ¹²⁵I-labelled guanyltyramine as ADPribose acceptor, formation of ADPribosyl ¹²⁵-I-guanyltyramine was linear with time and enzyme concentration. The product was distinguishable on both thin-layer and high-performance liquid chromatography from that formed by cholerangen. Using ¹²⁵I-guanyltyramine, ADPribosyltransferase acitivity was also demonstrated in crude turkey erythrocyte cytosolic and membrane fractions. When rat liver was fractioned, apparent activity was detected primarily in the microsomes. The NAD-dependent product of the microsomal reaction was, however, distinguished from the turkey erythrocyte transferase by thin-layer and DEAE-Sephadex chromatography; this product had a retention time identical to that of free ¹²⁵I on high-performance liquid chromatography. In addition to NAD, the microsomal deiodinase activity was supported by NADH, NADP and NADPH. Phenyl boronate selectively bound ADPribosyl ¹²⁵I-guanyltyramine and other metabolites of ¹²⁵I-guanyltyramine which were formed by microsomes in a NAD-dependent process. These metabolites were distinguished from ADPribosyl ¹²⁵I-guanyltyramine by high-performance liquid chromatography. These results indicate that in some cases, for example, turkey erythrocyte cytosolic and membrane fractions, ¹²⁵I-guanyltyramine can be used to quantify ADPribosyltransferases in crude mixtures, whereas in others, for example, rat liver microsomes, high-performance liquid chromatographic analysis must be used to identify products.     

Field studies on a social lizard: Home range and social organization in an Australian skink,Egernia major

Abstract Although most reptiles have polygynous mating systems without long‐term pair bonds, one lineage of large scincid lizards in Australia is exceptional in this respect. Reports of complex sociality in the genus Egernia led us to conduct the first radiotelemetric field study of a species within this group. Land mullets (Egernia major) are large (60 cm total length), viviparous lizards from rainforest habitats in south‐eastern Australia. To document the spatial ecology and social organization of this species, we captured 12 adult lizards in the Barrington Tops area of eastern New South Wales and implanted them with miniature radiotransmitters. The lizards were released at their sites of capture and located daily for the next 6 weeks. All of the radiotracked lizards had discrete home ranges of approximately 10 000 m², based around well‐defined core areas (approximately 2000–3000 m²). Females tended to move further, and to range over wider areas, than did males. All of the radiotracked lizards lived in social groups consisting of one or more adult males and females plus juveniles of all age classes. Subgroups were apparent within one group of five radio‐tagged lizards: individual animals consistently shared their shelter sites and home ranges with one or more specific individuals. Male/female pairings were more frequent than expected under the null hypothesis of random association among individuals. The data in the present study support anecdotal reports of pair bonds in E. major and support suggestions that the social systems of species in this genus are more complex than those of previously studied reptiles.