Modelled population growth based on reproduction differs from life tables based on age determination in Danish raccoon dogs ( Nyctereutes procyonoides )

The population of raccoon dogs (Nyctereutes procyonoides) in Denmark has increased rapidly from 1995 when the first was recorded until today where 3291 raccoon dogs are trapped, shot by hunters or road killed. The aims of this study are to present the first data on reproduction and life tables of raccoon dogs in Denmark and to compare mortality from modelled life tables with game bag records and sampled raccoon dogs in different age groups. In this study, the uteri of 89 adult females (> 10 months) were examined for placental scars (PSC), and 561 individuals (289 males, 272 females) were aged using pulp cavity width and dental lines in canine teeth. The litter size of raccoon dogs in Denmark is to date the largest litter size recorded in the wild (mean ± SE) 10.8 ± 0.4, range 1–16 pubs and fecundity 8.4 ± 0.6 pubs. The percent-reproducing females are 78–83%, based on dark and all PSC, respectively. A significant difference was found between the proportion of individuals composing the different age groups based on age determination of individuals collected (Ntage) and the modelled number of individuals in age groups based on fecundity and different mortality rate (Ntmodel), X2 = 8, p < 0.05. The discrepancy between the relatively high reproduction and lifetables may be due to older and more experienced animals that avoid culling. A low population density in a newly founded Danish population of raccoon dogs, together with a milder climate where raccoon dogs can forage during the winter, may cause an exceptionally high reproduction in Danish raccoon dogs.     

Higher-Order Looping and Nuclear Organization of Tcra Facilitate Targeted RAG Cleavage and Regulated Rearrangement in Recombination Centers

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Highlights? RAG-dependent monoallelic loop formation is linked to monoallelic RAG cleavage ? RAG enrichment, cleavage, and higher-order loop formation occur at the 3′ end of Tcra ? Looping out is a determinant of directed RAG targeting ? ATM-mediated control of looping out is linked to the maintenance of genome stability     

Loss of Drosophila borealin causes polyploidy, delayed apoptosis and abnormal tissue development

The chromosomal passenger complex (CPC) is a key regulator of mitosis in many organisms, including yeast and mammals. Its components co-localise at the equator of the mitotic spindle and function interdependently to control multiple mitotic events such as assembly and stability of bipolar spindles, and faithful chromosome segregation into daughter cells. Here, we report the first detailed characterisation of a CPC mutation in Drosophila, using a loss-of-function allele of borealin (borr). Like its mammalian counterpart, Borr colocalises with the CPC components Aurora B kinase and Incenp in mitotic Drosophila cells, and is required for their localisation to the mitotic spindle. borr mutant cells show multiple mitotic defects that are consistent with loss of CPC function. These include a drastic reduction of histone H3 phosphorylation at serine 10 (a target of Aurora B kinase), a pronounced attenuation at prometaphase and multipolar spindles. Our evidence suggests that borr mutant cells undergo multiple consecutive abnormal mitoses, producing large cells with giant nuclei and high ploidy that eventually apoptose. The delayed apoptosis of borr mutant cells in the developing wing disc appears to cause non-autonomous repair responses in the neighbouring wild-type epithelium that involve Wingless signalling, which ultimately perturb the tissue architecture of adult flies. Unexpectedly, during late larval development, cells survive loss of borr and develop giant bristles that may reflect their high degree of ploidy.     

Condensation of interphase chromatin in nuclei of synchronized chinese hamster ovary (CHO-K1) cells

Reversibly permeabilized cells have been used to visualize interphase chromatin structures in the presence and absence of biotinylated nucleotides. By reversing permeabilization, it was possible to confirm the existence of a flexible chromatin folding pattern through a series of transient geometric forms such as supercoiled, circular forms, chromatin bodies, thin and thick fibers, and elongated chromosomes. Our results show that the incorporation of biotin-11-dUTP interferes with chromatin condensation, leading to the accumulation of decondensed chromatin structures. Chromatin condensation without nucleotide incorporation was also studied in cell populations synchronized by centrifugal elutriation. After reversal of permeabilization, nuclei were isolated and chromatin structures were visualized after DAPI staining by fluorescent microscopy. Decondensed veil-like structures were observed in the early S phase (at an average C-value of 2.21), supercoiled chromatin later in the early S (2, 55 C), fibrous structures in the early mid S phase (2, 76 C), ribboned structures in the mid-S phase (2, 98 C), continuous chromatin strings later in the mid-S phase (3,28), elongated prechromosomes in the late S-phase (3, 72 C), precondensed chromosomes at the end and after the S phase (3, 99 C). Fluorescent microscopy revealed that neither interphase nor metaphase chromosomes are separate entities but form a linear array arranged in a semicircle. Linear arrangement was confirmed by computer image analysis.     

Unusual sialilation of three different rare genetic variants of serum DBP: Gc 1A17, Gc 1A16, and Gc 1A11

Summary The proteins of three anodal Gc1 variants, Gc 1A16, 1A11, and 1A17, are characterized by the most acidic isoelectric points observed so far among the different Gc mutants. Stepwise removal of N-acetylneuraminic acid (NANA) by treatment with neuraminidase was performed to estimate the degree of sialilation of these Gc variants. The results indicate that both proteins, the anodal and the cathodal component of these Gc 1 mutants, carry sialic acid residues. This observation is remarkable in so far as usually only the anodal component of the Gc 1 protein contains NANA and only a single residue. From the experiments carried out it can be deduced that Gc 1A16 has two NANA residues in the anodal and one NANA residue in the cathodal component. Gc 1A16 was found in four members of three generations in a Danish family; the variant segregated as a Mendelian trait. More difficult to interprete are the results obtained with the variants Gc 1A11 and Gc 1A17. Gc 1A11 probably has three NANA residues in the anodal and two NANA residues in the cathodal component. Gc 1A11 has been observed in two mother-child pairs and is presumably also a simple genetic trait. Gc 1A17 has also several NANA residues in both Gc proteins; it is suggested that the anodal component has either three or four NANA residues and the cathodal component either two or three NANA residues. Family information on this variant is not yet available.     

Molecular mechanisms of determination in Drosophila

A number of Drosophila proteins have been identified that play key roles in the establishment of active or inactive states of selector gene expression. Interactions between these proteins and their target selector genes are beginning to be understood, shaping our molecular view as to how stable determination of cells is achieved.