Emission Inventories for SO2 and NOx in Developing Country Regions in 1995 with Projected Emissions for 2025 According to Two Scenarios

Water, Air, &; Soil Pollution - Top-down inventories of anthropogenic SO2 and NOx emissions were compiled for 1995 for developing country regions. Regional emission factors were used to generate...     

Two mosaic terminal inverted duplications arising post-zygotically: Evidence for possible formation of neo-telomeres

Objective

To elucidate the structure of terminal inverted duplications and to investigate potential mechanisms of formation in two cases where there was mosaicism with cells of apparently normal karyotype.

Results

A karyotype [46,XY,inv dup(4)(p16.3p15.1)/46,XY] performed on blood lymphocytes from a patient referred for developmental delay (case 1) demonstrated a normal karyotype in 60% of cells with a terminal inverted duplication 4p in the remainder. In case 2, referred for multiple fetal anomalies on an ultrasound scan, 33% of amniocyte colonies were karyotypically normal, with a terminal inv dup 10p in the remainder [46,XX,inv dup(10)(p15.3p11)/46,XX]. Duplicated FISH signals for GATA3 and NEBL loci (in case 2), and for the Wolf-Hirschhorn locus (case 1) confirmed the inverted structure of both duplications. In the GTL banded normal cells from both cases, there was a cryptic deletion detected by FISH of one copy of the subtelomere 4p (case 1, probe GS-36P21), and subtelomere 10p (case 2, probe GS-306F7). At pter on both inv dup chromosomes there was no FISH signal present for the specific subtelomere probe. However, a positive pantelomeric probe signal was detected at 4 pter and 10 pter in both the cryptically-deleted chromosomes and the inv dup chromosomes in the respective cell lines of both cases.

Conclusion

An inv dup structure was evident for both cases on GTL bands, and confirmed by the various FISH studies. The presence of telomere (TTAGGG repeat) sequences at pter on the inv dup chromosomes (where more proximal chromosome specific subtelomeric probes were negative) was indicated by the pantelomeric probe signals in both cases. We conclude the most likely mechanism of origin in both cases was by sub-telomeric breakage in the zygote at pter, and delayed repair/rearrangement until after one or more subsequent mitotic divisions. In these divisions, at least one breakage-fusion-bridge cycle occurred, to produce inverted duplications. It is proposed then that two differently "repaired" daughter cells proliferated in parallel. In one daughter cell line (with an overtly normal karyotype) there was deletion of the subtelomere and presumed repair through capping by a neo-telomere (i.e. "healing", as initially proposed by McClintock). This occurred in both cases presented. In the other daughter cell of each case, it is proposed that chromosome stabilization was achieved (after replication) by sister chromatid reunion to form a dicentric, which broke at a subsequent anaphase, to form an inverted duplication (with loss of the reciprocal product, and the other daughter cell line). One inv dup was repaired without an interstitial specific subtelomere (case 1) and one was repaired with a duplicated specific interstitial subtelomere (case 2). After repair TTAGGG repeats were detected by FISH at each respective new pter.

     

Horizontal moment around the hoof centre of pressure during walking on right and left circles

Reasons for performing study: Recent research indicates that the digital joints experience some degree of extrasagittal motion during stance and that the moments under the hoof are asymmetric in horses walking in a straight line. On a circle, these have not been defined. Objectives: To quantify the amplitude and symmetry of horizontal twisting moments around the vertical axis through the hoof's centre of pressure on left and right circles at walk. Methods: Six Thoroughbred horses were led at walk across a Kistler force platform on a left and a right circle of 5 m radius. The resultant moment around the hoof was calculated from the 4 horizontal forces and their moment arms. Results: Five of the 6 horses exerted an internal moment around their left forehoof, and 4 exerted an internal moment around their right forehoof on the left circle. On the right circle, 5 of the 6 exerted an internal moment around the left forehoof and a weak external moment around the right forehoof. The moments under the hind hooves were bilaterally similar for right and left circles. Conclusion: Intrahorse variability in the applied moments is low, but there is some interhorse variability, especially in the forelimb moments, that indicates future studies of movements of the distal limb joints should be bilateral to account for mechanical asymmetry. Potential relevance: The finding that horizontal moments vary between forelimbs in some horses will apply to how exercise on a circle is approached, especially in rehabilitation programmes for horses with orthopaedic injury of the distal limb.     

Chromosome loops arising from intrachromosomal tethering of telomeres occur at high frequency in G1 (non-cycling) mitotic cells: Implications for telomere capture

BACKGROUND: To investigate potential mechanisms for telomere capture the spatial arrangement of telomeres and chromosomes was examined in G1 (non-cycling) mitotic cells with diploid or triploid genomes. This was examined firstly by directly labelling the respective short arm (p) and long arm subtelomeres (q) with different fluorophores and probing cell preparations using a number of subtelomere probe pairs, those for chromosomes 1, 3, 4, 5, 6, 7, 9, 10, 12, 17, 18, and 20. In addition some interstitial probes (CEN15, PML and SNRPN on chromosome 15) and whole chromosome paint probes (e.g. WCP12) were jointly hybridised to investigate the co-localization of interphase chromosome domains and tethered subtelomeres. Cells were prepared by omitting exposure to colcemid and hypotonic treatments. RESULTS: In these cells a specific interphase chromosome topology was detected. It was shown that the p and q telomeres of the each chromosome associate frequently (80% pairing) in an intrachromosomal manner, i.e. looped chromosomes with homologues usually widely spaced within the nucleus. This p-q tethering of the telomeres from the one chromosome was observed with large (chromosomes 3, 4, 5), medium sized (6, 7, 9, 10, 12), or small chromosomes (17, 18, 20). When triploid nuclei were probed there were three tetherings of p-q subtelomere signals representing the three widely separated looped chromosome homologues. The separate subtelomere pairings were shown to coincide with separate chromosome domains as defined by the WCP and interstitial probes. The 20% of apparently unpaired subtelomeric signals in diploid nuclei were partially documented to be pairings with the telomeres of other chromosomes. CONCLUSIONS: A topology for telomeres was detected where looped chromosome homologues were present at G1 interphase. These homologues were spatially arranged with respect to one-another independently of other chromosomes, i.e. there was no chromosome order on different sides of the cell nuclei and no segregation into haploid sets was detected. The normal function of this high frequency of intrachromosomal loops is unknown but a potential role is likely in the genesis of telomere captures whether of the intrachromosomal type or between non-homologues. This intrachromosomal tethering of telomeres cannot be related to telomeric or subtelomeric sequences since these are shared in varying degree with other chromosomes. In our view, these intrachromosomal telomeric tetherings with the resulting looped chromosomes arranged in a regular topology must be important to normal cell function since non-cycling cells in G1 are far from quiescent, are in fact metabolically active, and these cells represent the majority status since only a small proportion of cells are normally dividing.     

Horizontal moment around the hoof's centre of pressure during walking in a straight line

Reasons for performing study: Joint congruity and ligaments restrain the distal limb joints from excessive motion in the transverse and frontal planes, but the magnitudes and direction of the horizontal twisting moments around the hoof's centre of pressure (CoP) that induce these motions are unknown. Objectives: To quantify the horizontal moment around the vertical axis through the hoof's CoP at walk, and to determine whether these are symmetric. Methods: Nine sound Thoroughbred horses (mean age 5.3 years; mean mass 502 kg) were led at walk in a straight line across a Kistler force platform. Five trials were collected for each fore and hindlimb. The resultant moment around the hoof's CoP was calculated from the horizontal moment arms between the calculated CoP and the 4 horizontal forces in the transverse (X) and cranio‐caudal (Y) directions. Results: The calculated moments were consistent within limbs and horses, but variable between horses. Hindlimbs demonstrated a biphasic moment pattern and the largest moments were typically in the first half of stance. Mean ± s.d. peak moments were internal under both hindlimbs (L: Int 14.1 ± 4.6 Nm; R: Int 13.3 ± 5.5 Nm). In the forelimbs, 7/9 horses demonstrated an asymmetric moment pattern, with the left forelimb exerting an internal moment (L: Int 6.9 ± 2.9 Nm) and the right forelimb an external moment (R: Ext 8.4 ± 4.4 Nm), while the remaining 2 horses exerted internal moments in both forelimbs (L: Int 11.7 ± 1.4 Nm; R: Int 6.6 ± 1.9 Nm). Conclusion: In 7/9 horses, the forelimbs exerted asymmetric horizontal moments around the hoof CoP. The hindlimbs appear to behave with mechanical symmetry during stance, exerting an internal moment during retraction. Potential relevance: Extrasagittal joint motions in the forelimb are unlikely to be symmetric and future studies should account for possible bilateral variations.