Homeotic protein binding sites, origins of replication, and nuclear matrix anchorage sites share the ATTA and ATTTA motifs.

Nuclear matrix organizes the mammalian chromatin into loops. This is achieved by binding of nuclear matrix proteins to characteristic DNA landmarks in introns as well as proximal and distal sites flanking the 5' and 3' ends of genes. Matrix anchorage sites (MARs), origins of replication (ORIs), and homeotic protein binding sites share common DNA sequence motifs. In particular, the ATTA and ATTTA motifs, which constitute the core elements recognized by the homeobox domain from species as divergent as flies and humans, are frequently occurring in the matrix attachment sites of several genes. The human apolipoprotein B 3' MAR and a stretch of the Chinese hamster DHFR gene intron and human HPRT gene intron shown to anchor these genes to the nuclear matrix are mosaics of ATTA and ATTTA motifs. Several origins of replication also share these elements. This observation suggests that homeotic proteins which control the expression level of many genes and pattern formation during development are components of the nuclear matrix. Thus, the nuclear matrix, known as the site of DNA replication, might sculpture the crossroads of the differential activation of origins during development and S-phase and the control of gene expression and pattern formation in embryogenesis.     

Eimeria tenella: Vitamin Requirements for Development in Primary Cultures of Chicken Kidney Cells

SYNOPSIS. Development of Eimeria tenella was studied in primary cultures of chicken kidney cells maintained in Medium 199 lacking each of the following: vitamin A. biotin, p -aminobenzoic acid, folic acid, nicotinamide, Ca pantothenate, pyridoxine, pyridoxal, riboflavin, thiamin, ascorbic acid, calciferol, α-tocopherol, and menadione. Data obtained concerning numbers of mature schizonts or total numbers of parasites or both indicated that all of the vitamins are needed for 1st- and 2nd-generation schizogony, and all except calciferol and folic acid are needed for gametogony.     

Development, adult size and fecundity of Aphidius sonchi reared in two instars of its aphid host, Hyperomyzus lactucae

Development, adult size and fecundity of the aphid parasite, Aphidius sonchi Marshall (Hymenoptera: Aphidiidae), which began their development in the first and third instar nymphs of Hyperomyzus lactucae (L.) (Homoptera: Aphididae), were studied in the laboratory. Survival and development times were almost identical in the two host instars. However, adult parasites reared in the first instar hosts were smaller and had fewer eggs at emergence than those reared from the third instar.Further analysis showed that the size of an adult parasite, irrespective of host stage at reception of the parasite egg, was largely determined by the size of the host when the parasite was in its destructive feeding phase. Furthermore, within parasites reared from each of the two host instars, the earlier emerging individuals were larger and contained more eggs on emergence. However, the relationships between size, development time and fecundity in the parasites differed significantly between cohorts reared from the two host instars.These results indicate that (1) the suitability of the aphid to the development of the parasite varies as the aphid develops, and (2) several aspects of the parasite biology must be studied to show the relative suitability of the aphids of a given instar.

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Résumé L'étude a porté sur le développement, la fécondité et la taille des adultes d'A. sonchi Marshall (Hym: Aphidiidae) qui commence son développement dans le ler et le 3ème stades larvaires d'H. lactucae (Homopt: Aphididae). La survie et la durée de développement sont presque identiques dans les hôtes des deux stades. Cependant les adultes élevés dans le ler stade de l'hôte étaient plus petits et avaient moins d'oeufs à l'émergence que ceux élevés dans le 3ème stade.Des observations ultérieures ont montré que la taille de l'adulte, indépendamment du stade de l'hôte au moment de la réception de l'oeuf, était fortement déterminée par la taille de l'hôte au moment où la larve du parasite était dans sa phase alimentaire destructrice. De plus, parmi les parasites élevés à partir des hôtes de chacun des deux stades, les premiers émergés étaient plus gros et contenaient plus d'oeufs. Cependant la relation entre taille, durée de développement et fécondité des parasites différait significativement suivant les cohortes élevées à partir des hôtes des deux stades.Ces résultats indiquent (1) que l'adéquation du puceron au développement du parasite change pendant que le puceron se développe et (2) que différents aspects de la biologie du parasite doivent être étudiés pour montrer l'adéquation relative des pucerons d'un stade donné.

     

Physiological interaction model of sunflower plant with its nutrient medium during ontogenesis

A study was conducted with sunflower plants (Helianthus annuus, L.) cv. Peredovik in field experiments, one of which included 9 NPK-fertilizer treatments. The intensity of uptake,i.e. the quantity (mg) of nutrient taken up for the accumulation of 1 g dry matter/day, the concentrations of all essential elements in the plant organ tissues and their distribution among above-ground organs, by stages of development, were investigated. The results have revealed the inherent physiological system responsible for the uptake intensity of individual elements, as well as the simultaneous uptake and distribution of all essential elements of the root nutrition by the shoots, throughout the life cycle of the plant.     

A quantitative estimation of sequential foliage development and fertility inDryopteris crassirhizoma

The foliage development ofDryopteris crassirhizoma Nakai was quantitatively estimated by measurements of shape and size of leaves from different developmental stages of sporophytes, to lead to an understanding of the life history characteristics of the species. The number of midrib branches (NV, number of veins) of the leaf corresponds to the leaf-shape complexity (DI, dissection index; shape complexity from a circle) and length of leafblade (BL). Some quantitative characters, such as leaf uniformity (decrease in NV variation), changes in shape and increase in number of leaves, vary progressively during foliage formation. The sequence of foliage development can be quantified using the parameter NV: for example, 15-NV for leaf uniformity, 30-NV for leaf-shape change from triangular to oblanceolate, 60-NV for increase in leaf number and leaf fertility in the course of sporophyte ontogeny. Contribution No. 3297 from the Institute of Low Temperature Science, Hokkaido University.     

Biology and epidemics of Candidatus Liberibacter species,psyllid‐transmitted plant‐pathogenic bacteria

Candidatus Liberibacter species are Gram‐negative bacteria that live as phloem‐limited obligate parasites in plants, and are associated with several plant diseases. These bacteria are transmitted by insects called psyllids, or jumping plant lice, which feed on plant phloem sap. Citrus huanglongbing (yellow shoot) or citrus greening disease is associated with three different species of Ca. Liberibacter – Ca. L. asiaticus, Ca. L. africanus and Ca. L. americanus – all originally found on different continents. Ca. L. asiaticus is the most severe pathogen, spread by Asian citrus psyllid Diaphorina citri and causing devastating epidemics in several countries. Ca. L. africanus occurs in Africa where it is spread by the African citrus psyllid Trioza erytreae. Ca. Liberibacter solanacearum is associated with diseases in several solanaceous plants, and transmitted by potato psyllid Bactericera cockerelli. Zebra chip disease is causing large damage in potato crops in North America. In Europe Ca. Liberibacter solanacearum is associated with diseases of the Apiaceae family of plants, carrot and celery, and transmitted by psyllids Trioza apicalis and Bactericera trigonica. When Ca. Liberibacter is suspected as the disease agent, the diagnosis is confirmed by DNA‐based detection methods. Ca. Liberibacter‐associated plant diseases can be controlled by using healthy plant propagation material, eradicating symptomatic plants, and by controlling the psyllid populations spreading the disease.     

MOLECULAR PHYLOGENETIC ANALYSIS OF LIFE-HISTORY EVOLUTION IN ASTERINID STARFISH

We analyzed phylogenetic relationships among 12 nominal species of starfish in the genera Patiriella and Asterina (Order Valvatida, Family Asterinidae), based on complete sequences for a mitochondrial protein coding gene (cytochrome oxidase subunit I) and five mitochondrial transfer RNA genes (alanine, leucine, asparagine, glutamine, and proline) (1923 bp total). The resulting phylogeny was used to test a series of hypotheses about the evolution of life-history traits. (1) A complex, feeding, planktonic larva is probably ancestral for these starfish, but this is not the most parsimonious reconstruction of ancestral larval states. (2) The feeding larval form was lost at least four times among these species, and three of these losses occurred among members of a single clade. (3) Small adult size evolved before both cases of hermaphroditism and viviparous brooding, but viviparity was not always preceded by an intermediate form of external brooding. (4) An ordered transformation series from feeding planktonic development to viviparous brooding has been predicted for starfish, but we could not find an example of this transformation series. (5) Viviparity evolved recently (< 2 Mya). (6) Both species selection and transformation of lineages may have contributed to the accumulation of species with nonfeeding development among these starfish. (7) Neither Asterina nor Patiriella are monophyletic genera. Larval forms and life-history traits of these starfish have evolved freely under no obvious constraints, contrary to the widely assumed evolutionary conservatism of early development.     

Are there Atlantic salmon in the River Tambre?

Genetic variability and assignment analyses demonstrate that the 60 returning adult salmon to the Tambre River in 2005 were not the product of an incipient wild population, but the result of straying from a neighbouring river.