Transient appearance of Strongylocentrotus purpuratus Otx in micromere nuclei: Cytoplasmic retention of SpOtx possibly mediated through an α-actinin interaction

At the 16-cell stage, the sea urchin embryo is partitioned along the animal-vegetal axis into eight mesomeres, four macromeres, and four micromeres. The micromeres, unlike the other blastomeres, are autonomously specified to produce skeletogenic mesenchymal cells and are also required to induce the vegetal-plate territory. A long-held belief is that micromeres inherit localized maternal determinants that endow them with their cell autonomous behavior and inducing capabilities. Here, we present evidence that an orthodenticle-related protein, SpOtx appears transiently in nuclei of micromeres but not in nuclei of mesomeres and macromeres. At later stages of development, SpOtx was translocated into nuclei of all cells. To address the possibility that SpOtx was retained In the cytoplasm at early developmental stages we searched for cytoplasmic proteins that interact with SpOtx. A proline-rich region of SpOtx resembling an SH3-binding domain was used to screen an embryo cDNA expression library, and a cDNA clone was isolated and shown to be α-actinin. A yeast two-hybrid analysis showed a specific interaction between the proline-rich region of SpOtx and a putative SH3 domain of the sea urchin α-actinin. Because micromeres lack an actin-based cytoskeleton, the results suggested that, at the vegetal pole of the 16-cell stage embryo, SpOtx was translocated into micromere nuclei, whereas in other blastomeres SpOtx was actively retained in the cytoplasm by binding to α-actinin. The transient appearance of SpOtx in micromere nuclei may be associated with the specification of micromere cell fate. © 1996 Wiley-Liss, Inc.     

Plasma and Urinary Luteinizing Hormone Levels in the Diagnosis of Endocrine Disease

The diagnostic value of measurements of plasma and urinary luteinizing hormone (LH) has been studied in 209 patients with endocrine disease. In 44 patients puberty was either delayed or had failed to occur. In those with chromosomal abnormalities the LH levels were often within the normal range, whereas those with a pituitary cause usually had low levels. In boys with delayed puberty plasma LH levels rose before physical changes occurred and had prognostic value. In patients with later gonadal failure, men with impotence or infertility, and women with secondary amenorrhoea LH assays proved of little value, although in one case a premature menopause was suspected and six patients with anorexia nervosa had low LH levels.Sixty patients with disorders of the hypothalamicpituitary area were studied. Levels of LH were measured and considered in relation to the other anterior pituitary hormones. Impairment of LH secretion was one of the first effects on hormone production of disease affecting this area, and this was, of course, most readily detected in postmenopausal women.The normal ranges of both plasma and urine LH are wide and there seems to be considerable day-to-day variation, especially of urinary output. Several samples should, therefore, be measured if therapeutic decisions are involved.     

Challenges in recruiting older twins for the Sri Lankan twin registry.

The National Twin Registry of Sri Lanka was established in 1997 as a volunteer register. To extend it to a population-based register, we examined the effectiveness of tracing older twins by inspecting birth records and recruiting them by postal invitation and in-person contact. Birth records at a divisional secretariat reported from 2 maternity hospitals between the years of 1954-1970 were scrutinised to identify a random sample of twins. These hospitals had the highest twin delivery rates for the whole country. We identified 620 twins and a questionnaire was mailed to them. Research assistants visited a cohort of non-respondents (71) in the postal survey. These 620 twins were identified after perusing 20700 birth records. The twinning rate was estimated at 29.95 ([620/20700] x 1000) twins per 1000 registered births (CI 27.63-32.27). In the postal survey, 37 (12%) responded and 62 letters were returned (20%). Both twins were still alive in 20 pairs, one was still alive in 15 pairs, and both twins were dead in 2 pairs. During field visits, 42 (59.2%) addresses were located. Information was available on 16 twin pairs. Both twins were alive in 8 pairs, one each in 4 pairs, and both were dead in 4 pairs and at least one twin was traced in 10 pairs (14%). Both the postal and the field survey gave a low yield. This finding is different from tracing younger twins born between 1985-1997 by using the same methods. Migration, urbanization and development in the country might have affected tracing older twins from the birth record addresses, which were decades old.     

Adsorption Mechanism of Cr(VI) onto Coir Pith

Reductive adsorption of Cr(VI) on coir pith (hereafter CP) was examined as a function of pH, ionic strength, and temperature. The CP contains 1.33 meq g^{? 1} phenolic, 0.43 meq g^{? 1} of lactonic, and 0.35 meq g^{? 1} carboxylic sites. Thus the CP surface is enriched with electron-donating oxygen functionalities. As evidenced by infrared (IR) spectroscopy, the Cr(VI) → Cr(III) conversion is facilitated by CP sites that are enriched with O─ O functional groups. The adsorption of reduced Cr(VI) was found to occur via C─ O─ functional groups first forming innersphere complexes with the CP surface, yielding keto (> C═ O) groups on the CP surface. The reductive adsorption of Cr(VI) was almost completed within 3 to 4 h, and it was dependent on pH and background ionic strength, yielding the highest monolayer coverage (9.56E-7 mol m^{? 2}) at pH 3.7 in 0.1 M NaNO₃. The Γ_Cr(III) followed the order with respect to the ionic strength: Γ_{0.1 M} > Γ_{0.01 M} > Γ_{0.001 M}. The initial rate constant, k _i , increased with temperature as k _i ^{313 K} > k _i ^{303 K} > k _i ^{293 K} > k _i ^{283 K}.     

Two Extracellular Matrices From Oocytes of the Marine Shrimp Sicyonia ingentis that Independently Mediate Only Primary or Secondary Sperm Binding

During spawning, female Sicyonia ingentis simultaneously release ova and stored nonmotile sperm and mix them externally to initiate gamete interaction. Sperm bind to a thin vitelline envelope (VE) via their anterior appendage and within seconds are induced to undergo acrosomal exocytosis. The sperm penetrate the VE and become secondarily bound to the surface coat (SC), a glycocalyx on the oocyte surface. In this study, both extracellular matrices were isolated from S. ingentis oocytes. Isolated VEs mediated only primary sperm binding (i.e., before the acrosome reaction), while the isolated SCs mediated only secondary sperm binding (i.e., after acrosomal exocytosis). Isolated S. ingentis VEs were used to characterize primary sperm binding activity. The two extracellular matrices differ morphologically and possess different polypeptide profiles. Soluble fractions of isolated VEs inhibited primary sperm binding in a concentration dependent manner, and immunolocalization of VE components demonstrated highly localized VE binding sites at the tip of the sperm anterior appendage by which sperm bind eggs. Extensive Pronase digestion of VE components did not affect sperm binding activity of solubilized VE components, while complete deglycosylation with trifluoromethanesulfonic acid destroyed sperm binding activity. However, neither alkaline treatment nor enzyme digestion using glycosidases specific for asparagine and serine/ threonine linked oligosaccharides affected sperm binding activity.     

A genome-wide survey of the evolutionarily conserved Wnt pathways in the sea urchin Strongylocentrotus purpuratus

The Wnt pathways are evolutionarily well-conserved signal transduction pathways that are known to play important roles in all Metazoans investigated to date. Here, we examine the Wnt pathway genes and target genes present in the genome of the echinoderm Strongylocentrotus purpuratus. Analysis of the Wnt genes revealed that eleven of the thirteen reported Wnt subfamilies are represented in sea urchin, with the intriguing identification of a Wnt-A ortholog thought to be absent in deuterostomes. A phylogenetic study of the Frizzled proteins, the Wnt receptors, performed throughout the animal kingdom showed that not all Frizzled subfamilies were present in the metazoan common ancestor, e.g. Fz3/6 emerged later during evolution. Using sequence analysis, orthologs of the vast majority of the cellular machinery involved in transducing the three types of Wnt pathways were found in the sea urchin genome. Furthermore, of about one hundred target genes identified in other organisms, more than half have clear echinoderm orthologs. Thus, these analyses produce new inputs in the evolutionary history of the Wnt genes in an animal occupying a position that offers great insights into the basal properties of deuterostomes.     

Pygidial gland chemistry and potential alarm-recruitment function in column foraging,but not solitary,Nearctic Messor harvesting ants (Hymenoptera: Formicidae: Myrmicinae)

We investigated the role of the pygidial gland on foraging behavior in two ecologically dominant column foraging Nearctic harvesting ants (Messor pergandei and Messor andrei). Using chemical analyses and behavioral tests, we show that n-tridecane is the major biologically active compound of pygidial gland secretions in both species, and that this chemical functions as a powerful alarm-recruitment pheromone. Another major compound of pygidial gland contents is benzaldehyde; this substance does not release behavioral reactions in M. pergandei workers but might function as a defensive secretion. Six solitary foraging Nearctic Messor and two column foraging Palearctic Messor species, did not have large pygidial gland reservoirs.