Differences in abundance of individual RNAs in normal and animalized sea urchin embryos

A library of cDNA clones was constructed representing polysomal polyadenylated RNA of mesenchyme blastulae of Strongylocentrotus purpuratus. Using this library, we determined whether or not individual RNA species are associated with animalization of embryos by zinc ions. Clones corresponding to the most actively synthesized RNAs during the period just prior to the mesenchyme blastula stage were selected by screening colonies with in vivo-labeled RNA. The most abundant of these were chosen for further study. Individual RNA abundance was measured as percent of mass of total polyadenylated RNA by hybridizing cDNA exhaustively with cloned DNA on filters. The RNAs in the selected, cloned sequences were present in abundances of 0.01 to 1% of the mass of polyadenylated RNA. Changes in abundance of individual RNA species occurred during normal development and departures from these developmental changes occurred in the zinc-animalized embryos. Two RNA species, which normally increase 10-fold in abundance, are drastically repressed and at least one RNA species increases in abundance dramatically in the animalized embryos. These departures from the normal program of presumptive gene expression may furnish insights into changes in the normal processes of development.     

Development of the skeleton in Japanese quail embryos

In the research fields of experimental embryology, teratological testing, and developmental engineering in avian species, a knowledge of normal embryonic development is necessary so that research may be performed efficiently and precisely. A series of normal stages based on external appearance has been established in both chicken and quail embryos. Those based on skeletal features, however, have not been elucidated. The present study newly established a series of normal stages for the development of the Japanese quail embryo skeleton. This series is composed of 15 stages determined by observing the timing of chondrification and calcification of the skeleton every 24 h, from 3 to 17 days of incubation. Cartilage and ossified bones were stained blue and red with Alcian blue 8GX and alizarin red S, respectively. These skeletogenous stages of the Japanese quail embryo will be useful as a normal control not only in studies of experimental embryology, teratological testing, and developmental engineering, but also in the analysis of mutant embryos with skeletal abnormalities.     

Comparative compositional mapping of chicken and quail chromosomes

The distribution of various isochore families on mitotic chromosomes of domestic chicken and Japanese quail was studied by the method of fluorescence in situ DNA--DNA hybridization (FISH). DNA of various isochore families was shown to be distributed irregularly and similarly on chromosomes of domestic chicken and Japanese quail. The GC-rich isochore families (H2, H3, and H4) hybridized mainly to microchromosomes and a majority of macrochromosome telomeric regions. In chicken, an intense fluorescence was also in a structural heterochromatin region of the Z chromosome long arm. In some regions of the quail macrochromosome arms, hybridization was also with isochore families H3 and H4. On macrochromosomes of both species, the pattern of hybridization with isochores of the H2 and H3 families resembled R-banding. The light isochores (L1 and L2 families) are mostly detected within macrochromosome internal regions corresponding to G bands, whereas microchromosomes lack light isochores. Although mammalian and avian karyotypes differ significantly in organization, the isochore distribution in genomes of these two lineages of the warm-blooded animals is similar in principle. On macrochromosomes of the two avian species studied, a pattern of isochore distribution resembled that of mammalian chromosomes. The main specific feature of the avian genome, a great number of microchromosomes (about 30% of the genome), determines a compositional specialization of the latter. This suggests the existence of not only structural but also functional compartmentalization of the avian genome.     

Distribution of interleukin-1 receptor in chicken and quail brain

Interleukin 1 isoforms (IL-1) are major regulators of vertebrate immune responses. In the mammalian CNS, this function is reflected in physiological and anatomical evidence implicating IL-1 in a suite of behaviors associated with sickness. Although birds show sickness behavior, a parallel role of IL-1 in birds has not been investigated. As proinflammatory effects of IL-1 are mediated via the IL-1 type I receptor (IL-1RI), we investigated the distribution of IL-1RI protein and mRNA after lipopolysaccharide challenge in brains of two avian species, the chicken and Japanese quail. In some respects, the neuroanatomic distribution of IL-1R mRNA and protein in chicken and Japanese quail resembled that reported in mammals and was consistent with its putative role in the physiology and behavior of sickness. For example, we found IL-1RI mRNA or IL-1RI immunoreactivity in lemnothalamic visual projection areas of the pallium, surrounding blood vessels in pallial areas, in the dorsomedial nucleus of the hypothalamus, in the nucleus taenia, in cerebeller Purkinje cells and the motor components of the trigeminal and vagus nuclei. However, in contrast to mammals, we did not find evidence of IL1-RI receptors in medial or lateral pallial structures, paraventricular nucleus, areas homologous to the arcuate nucleus, the choroid plexus, organum vasculosum of the lamina terminalis or the reticular activating system. The distribution of IL-1RI suggests that a role for IL-1 in sickness behavior is conserved in birds, but that roles in other putative mammalian functions (e.g. hypothalamic-pituitary-adrenal and gonadal axes regulation, transport through barrier-related tissues, arousal) may differ.     

Purification and comparison of quail and chicken pepsinogens]

Pepsinogens of quail and chick, specific to adult proventriculus, were purified and their properties were compared. These two pepsinogens are similar in regard to enzymological characters, amino acid compositions, and immunological characters.     

Absorption, transportation and digestion of egg white in quail embryos

The present study was done to reveal how egg white is taken up by embryonic tissues, the pathway through which egg white is transported, and the location where it is digested during the development of the quail Coturnix japonica. Antiserum against quail ovalbumin was raised in rabbit and used as a probe. By immunoelectron microscopy, the uptake of ovalbumin on a small scale by receptor-mediated endocytosis was observed in the ectodermal cells of the yolk sac on days four to seven of incubation. The uptake of egg white on a large scale by fluid-phase endocytosis took place in the cells generally referred to collectively as the 'albumen sac'. The ovalbumin was transported through the albumen sac into the extraembryonic cavity during days eight to 10, and then into the amniotic cavity through the amnion approximately on day 10. Ovalbumin was present in the intestinal lumen on days 11 and 14, but it was not digested in the intestinal epithelial cells. The ovalbumin was detected in the yolk of embryos after day 10. Immunoblot testing, as well as a fluoroimmunoassay, revealed that the location where the amount of ovalbumin was highest changed chronologically from the extraembryonic cavity on day 10 to the amniotic cavity on day 11, the intestinal lumen on day 12 and then to the yolk on day 13. Several low molecular proteins which cross-reacted with the antiserum were observed in the extracts of the yolk. The reaction producing these proteins depended on low pH (approximately 3.0) and was inhibited by pepstatin A. The ovotransferrin was similarly digested. These results indicate that egg white is, for the most part, transported through the albumen sac to the yolk via the extraembryonic cavity, the amniotic cavity, and the intestinal lumen, and is digested in the yolk by aspartic proteinases.     

Sex-specific and left-right asymmetric expression pattern of Bmp7 in the gonad of normal and sex-reversed chicken embryos

A genetic switch determines whether the indifferent gonad develops into an ovary or a testis. In adult females of many avian species, the left ovary is functional while the right one regresses. In the embryo, bone morphogenetic proteins (BMP) mediate biological effects in many organ developments but their roles in avian sex determination and gonadal differentiation remains largely unknown. Here, we report the sex-specific and left-right (L-R) asymmetric expression pattern of Bmp7 in the chicken gonadogenesis. Bmp7 was L-R asymmetrically expressed at the beginning of genital ridge formation. After sexual differentiation occurred, sex-specific expression pattern of Bmp7 was observed in the ovary mesenchyme. In addition, ovary-specific Bmp7 expression was reduced in experimentally induced female-to-male reversal using the aromatase inhibitor (AI). These dynamic changes of expression pattern of Bmp7 in the gonad with or without AI treatment suggest that BMP may play roles in determination of L-R asymmetric development and sex-dependent differentiation in the avian gonadogenesis.     

Novel methods for studying normal and disordered erythropoiesis

Erythropoiesis is a process during which multipotential hematopoietic stem cells proliferate, differentiate and eventually form mature erythrocytes. Interestingly, unlike most cell types, an important feature of erythropoiesis is that following each mitosis the daughter cells are morphologically and functionally different from the parent cell from which they are derived, demonstrating the need to study erythropoiesis in a stage-specific manner. This has been impossible until recently due to lack of methods for isolating erythroid cells at each distinct developmental stage. This review summarizes recent advances in the development of methods for isolating both murine and human erythroid cells and their applications. These methods provide powerful means for studying normal and impaired erythropoiesis associated with hematological disorders.     

Aorta elastin turnover in normal and hypercholesterolemic Japanese quail

The turnover and degradation of mature elastin from the aortae of Japanese quail were estimated following with l-[U-¹⁴C]lysine by measuring the changes in specific activity of l-[U-¹⁴C]lysine and ¹⁴C-labelled desmosine and isodesmosine (crosslinking amino acids derived from lysyl residues) in elastin over a 39-week period. Only 5% of the variation in radioactivity could be attributed to changes in time. Therefore, it was concluded that the best estimates of mature elastin turnover are only quantifiable in years. Dietary cholesterol in amounts sifficient to induce plaque formation and fragmentation of the elastic lamina in the aorta did not significantly influence turnover time. It would appear that once the total pool of elastin in aorta is stabilized as mature fibers it is not subject to proteolysis or resynthesis of sufficient magnitude to result in measurable turnover.     

Equalization of Z and W axes in chicken and quail oocytes.

The different morphological types of ZW pairs have been classified in three main types according to the relative extension of the free segment of the Z axis: 1, "long asynaptic segment;" 2, "medium asynaptic segment;" and 3, "equalized." Pre- and post-pairing types have also been defined. Frequencies of each type were determined at day 20 and day 21 of incubation, and one and three days after hatching. The changing frequencies and the morphological transitions observed show a definite sequence of ZW types that can be used as a timetable for pachytene substaging. Measurements made on each ZW type show that the Z axis of the chicken shortens from 20.6 microns to 13.1 microns. This shortening occurs both in the free segment (at a higher rate) and in the paired segment (at a lower rate). The synaptonemal complex becomes elongated while adjustment occurs. The equalized Z axis makes many twists around the W axis. However, a segment 1 micron long from the synaptic terminus is free from twists and is assumed to be the homologously paired region. The ZW pair of the quail shows a similar behavior but equalization of the Z and W axes ends earlier and forms a straighter synaptonemal complex as compared with the chicken. In both species a recombination nodule is strictly localized near the synaptic terminus. In the ZW pair of the quail the average location of this nodule is 0.14 microns from the synaptic terminus. The meiotic behavior of ZW pairs in birds may be conserved.