Tempo and mode of concerted evolution in the L1 repeat family of mice

A 300-bp DNA sequence has been determined for 30 (10 from each of three species of mice) random isolates of a subset of the long interspersed repeat family L1. From these data we conclude that members of the L1 family are evolving in concert at the DNA sequence level in Mus domesticus, Mus caroli, and Mus platythrix. The mechanism responsible for this phenomenon may be either duplicative transposition, gene conversion, or a combination of the two. The amount of intraspecies divergence averages 4.4%, although between species base substitutions accumulate at the rate of approximately 0.85%/Myr to a maximum divergence of 9.1% between M. platythrix and both M. domesticus and M. caroli. Parsimony analysis reveals that the M. platythrix L1 family has evolved into a distinct clade in the 10-12 Myr since M. platythrix last shared a common ancestor with M. domesticus and M. caroli. The parsimony tree also provides a means to derive the average half-life of L1 sequences in the genome. The rates of gain and loss of individual copies of L1 were estimated to be approximately equal, such that approximately one-half of them turn over every 3.3 Myr.      

Effects of thymoquinone on liver miRNAs and oxidative stress in Ehrlich acid mouse solid tumor model

We investigated the effects of thymoquinone (TQ) on the expression of liver microRNAs (miRNAs), liver histopathology and oxidative stress in Ehrlich acid solid tumor model induced mice. We used 24 male BALB/c mice divided randomly into three groups. Control (C) group mice were injected intraperitoneally (i.p.) with 0.5 ml saline for four weeks. Tumor (T) group mice were injected i.p. with 0.5 ml saline for four weeks, then Ehrlich acid tumor cells were injected subcutaneously into the neck to induce solid tumor formation. TQ (T + Tq) group mice injected i.p. with 10 mg/kg TQ for four weeks, then Ehrlich acid tumor cells were injected subcutaneously into the neck of the mice in this group to induce solid tumor formation. At the end of the study, liver from all groups were removed for histopathological and miRNAs analysis, and oxidative stress measurement. We found that the expression of miR-206b-3p was up-regulated and the oxidative stress and necrosis increased in the liver tissue of mice with Ehrlich acid solid tumor. TQ application decreased the oxidative stress, prevented necrosis, increased regeneration and down-regulated the expression of miR-206b-3p in the liver tissue.     

Evaluations of wasted mouse fibroblasts and SV-40 transformed human fibroblasts as models of ataxia telangiectasia in vitro

Fibroblast cultures from wasted mice have been derived and the responses of these cultures to bleomycin treatment or gamma-irradiation have been examined. No differences were observed between wasted fibroblasts and littermate controls in the post-treatment inhibition of DNA replication. In contrast, a human SV-40 transformed ataxia telangiectasia fibroblast line mimicked the abnormal response of primary ataxia telangiectasia fibroblasts to gamma-rays or bleomycin and thus appears to be a useful in vitro model of ataxia telangiectasia.     

Autoantibodies specific for apoptotic U1-70K are superior serological markers for mixed connective tissue disease

Modifications occurring on autoantigens during cell death have been proposed to have a role in the initiation of autoimmune diseases. Patients suffering from mixed connective tissue disease (MCTD) produce autoantibodies directed to U1 small nuclear ribonucleoprotein (snRNP), and antibodies against a 70 kDa protein component, the U1-70K (70K) protein, are the most prominent. During apoptosis, 70K is cleaved by caspase-3 to a 40 kDa product, which remains associated with the complex. Autoantibodies preferentially recognizing the apoptotic form of 70K have been described previously, and an apoptosis-specific epitope on 70K has been identified. This study shows that 29 of 53 (54%) MCTD sera preferentially recognize the apoptotic form of 70K over intact 70K. Moreover, we show that antibodies directed to an apoptosis-specific epitope on 70K are more specifically associated with MCTD than other anti-70K antibodies, suggesting that apoptotic 70K is a better antigen for the detection of these antibodies in MCTD patients. Longitudinal analysis of 12 MCTD patients showed in several patients that early sera are relatively enriched with antibodies recognizing an apoptosis-specific epitope, and that the levels of these apoptosis-specific antibodies decrease in time. These findings indicate that the early detection of apoptotic 70K is of considerable interest for anti-U1 snRNP-positive patients.     

Prenatal diagnosis by linkage: hemophilia A and polymorphic glucose-6-phosphate deydrogenase.

Close linkage between the loci for G6PD and hemophilia A allows prenatal diagnosis of hemophilia in the fetuses of certain women who are heterozygous for two electrophoretic types of G6PD. A pregnant woman, whose mother was an obligate heterozygote for hemophilia, had factor VIII levels and a G6PD phenotype that failed to indicate clearly whether or not she was heterozygous for hemophilia. The G6PD phenotype of her male fetus revealed that the fetus was unlikely to have hemophilia.     

Experimental evidence for latent developmental plasticity: intertidal whelks respond to a native but not an introduced predator

Animals with highly inducible traits may show no inducible response when exposed to a related but wholly novel cue. This appears to be true for the intertidal whelk Nucella lamellosa faced with a voracious introduced predator. In the laboratory, we exposed whelks to effluent from two species of predatory crab, the native red rock crab Cancer productus and the invasive European green crab Carcinus maenas. Nucella and Cancer have a long shared history in the northeast Pacific, whereas potential interaction with Carcinus began here less than 10 years ago. Although Nucella responded adaptively to Cancer effluent by increasing shell thickness and decreasing somatic growth, there was no such response to Carcinus. Furthermore, thicker shelled Nucella were less likely to be eaten by Carcinus. Because Nucella produces thicker shells when exposed to Cancer cues, its ability to respond similarly to Carcinus depends only on the coupling of the Carcinus cue to the existing developmental pathways for adaptive changes in shell form. Such coupling of latent plasticity to a novel cue -- via genetic changes or associative learning -- could explain many cases of rapid phenotypic change following a sudden shift in the environment.     

Study of the mitotic and meiotic chromosomes of sotol (<i>Dasylirion cedrosanum</i> Trel.)

The genus Dasylirion is a group of plants typically present in the Chihuahuan Desert, perennial, with a dioecious sexual behavior and commonly called sotoles. This genus has been little studied from the biological point of view, and the bases of its reproductive response remain unknown. In this work we studied the chromosome number and meiotic response of Dasylirion cedrosanum in the county of Saltillo, Coahuila, located at the North East of Mexico. For the preparation of mitotic chromosomes, we used a technique based on enzymatic treatment with pectolyase and cellulase, as well as staining with acetocarmin dye. For the study of meiosis, male flower buds were collected, fixed and stained for analysis with the same dye. As a result, the gametic (n = x = 19) and somatic chromosome (2n = 38) numbers of D. cedrosanum are reported for the first time, being consistent with previous findings in other Dasylirion species, which points to a constant ploidy level across the genus. Variation was observed in the morphology and size of the somatic chromosomes, with types ranging from submetacentric to subtelocentric, and sizes oscillating in a range of 4.43 µm, with an average total length of 112.38 µm for the diploid chromosome complement. This shows that the chromosome complement of D. cedrosanom would belong to a 3B classification of Stebins, with a medium variation between chromosome lengths and low chromosome asymmetry. This variation indicates the feasibility of constructing a chromosome ideotype for this species. The meiotic chromosome pairing showed a chromosome behavior consistent with a disomic inheritance characteristic of a diploid species, with prevalence of ring and chain bivalents, typically without pairing abnormalities. Bivalent configurations in all cases were symmetrical.The normal and symmetrical meiotic pairing indicates a balanced production of gametes, and suggests the absence of heteromorphic sex determination.     

The F-type 5' motif of mouse L1 elements: a major class of L1 termini similar to the A-type in organization but unrelated in sequence

It has previously been shown that the L1 family in the mouse (L1Md) contains two alternative 5' ends called the A- and F-type sequences (1,2). We show here that the F-type element is a major class of murine L1 elements and report on the details of organization of the 5' motif of these F-type elements. Although the A- and F-type 5' sequences share no detectable sequence homology the organization of an F-type 5' end is strikingly similar to that of an A-type. That is, the F-type 5' sequences consist of a tandem array of a small number of 206 bp monomers while the A-type 5' motif consists of a tandem array of 208 bp monomers. All of the A-type elements characterized to date have a truncated monomer at the 5' end of the array. Many of the F-type elements are also terminated at the 5' end by a truncated copy but unlike the A-type elements some F-type elements terminate with a monomer which is within a few nucleotides of being complete. In addition the F-type consensus sequence, in contrast to the A-type sequence, shows homology (70%) to the body of the L1Md starting at the position where the monomer joins the rest of the L1 element.