Chromosome number and chromosome variation in embryos ofEvechinus chloroticus(Echinoidea: Echinometridae): Is there conservation of chromosome number in the Phylum Echinodermata? New findings and a brief review

A very large proportion of plants regenerated from anther culture of triticale F1 hybrids do not show the euploid number of chromosomes. Of 408 androgenetic plants checked for their chromosome numbers, 228 were aneuploid, of which 39 had one or several telosomes. Two observations suggest that most of the chromosome variations observed probably preexist in microspores of the F1 hybrids and would be caused by meiotic irregularities: on the one hand, the majority of these phenomena involve R-genome chromosomes, which also give rise to meiotic univalents; on the other hand, the chromosome number frequency distribution of the microspores from a fairly asyndetic hybrid fits well with that of the androgenetic plants. Thus aneuploidy and chromosome rearrangement do not implicate the in vitro technique itself but rather the choice of the material in triticale.Key words: × triticosecale, in vitro culture, chromosome variation, aneuploidy, C-banding.

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Numerical chromosome polymorphism in Mikania cordifolia Willd. (Asteraceae)

Genetics and Molecular Biology ◽

10.1590/s1415-47571999000400023 ◽

1999 ◽

Vol 22 (4) ◽

pp. 609-612 ◽

Cited By ~ 2

Author(s):

E.M.D. Maffei ◽

M.A. Marin-Morales ◽

P.M. Ruas ◽

C.F. Ruas

Keyword(s):

Chromosome Number ◽

Chromosome Pair ◽

Secondary Constriction ◽

Southeastern Brazil ◽

Chromosome Polymorphism ◽

Chromosome Variation ◽

Numerical Chromosome ◽

Numerical Variation ◽

Cytogenetical Analysis

Cytogenetical analysis of Mikania cordifolia, from southeastern Brazil, using the conventional Feulgen method, showed a chromosome number of 2n = 36. Previous karyotypic descriptions for this species showed a numerical chromosome variation of 2n = 34 to 38. There was a secondary constriction in every metaphase in the first chromosome pair, which constitutes a cytological marker. Small extranumerary chromosomes with numerical variation in the same plant were found in the tenth chromosome pair.

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Chromosome Variation in the Males of Some Australian Lygaeidae (Hemiptera: Heteroptera).

Australian Journal of Zoology ◽

10.1071/zo9790709 ◽

1979 ◽

Vol 27 (5) ◽

pp. 709 ◽

Cited By ~ 1

Author(s):

MB Malipatil

Keyword(s):

Chromosome Number ◽

Chromosome Pair ◽

Sex Chromosome ◽

Supporting Evidence ◽

Chromosome Variation

Twenty-one species of Australian lygaeids belonging to six subfamilies have been examined cytologically. The two species of Lygaeinae both have 2n B = 14 including an XY sex chromosome pair. While all the remaining species were also XY in the male, diploid numbers of 12, 14, 16, 20 and 22 were found. which included a minute m-chromosome pair which is not represented in the Lygaeinae. The observed variation in chromosome number and size provides supporting evidence for the occurrence of both fusion and fission within the Heteroptera.

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Further studies on the ultrastructure of the cochlea

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100159746 ◽

1990 ◽

Vol 48 (3) ◽

pp. 440-441

Author(s):

Zhixian Wang ◽

Pinjin Zhu ◽

Jianhe Sun ◽

Xuezheng Song

Keyword(s):

Hair Cells ◽

Military Medicine ◽

Outer Hair Cells ◽

Apical Surface ◽

Epithelial Surface ◽

Hearing Research ◽

New Findings ◽

Fine Structures ◽

Temporal Bones ◽

Accurate Observation

Hearing research is important not only for clinical, professional and military medicine, but also for toxicology, gerontology and genetics. Ultrastructure of the cochlea attracts much attention of electron microscopists, (1―3) but the research lags far behind that of the other parts of the organnism. On the basis of careful microdissection, technical improvment and accurate observation, we have got some new findings which have not been reported in the literature.We collected four cochleas from human corpses. Temporal bones dissected 1 h after death and cochleas perfused with fixatives 4 h after death were good enough in terms of preservation of fine structures. SEM:The apical surface of OHCs (Outer hair cells) and DTs (Deiters cells) is narrower than that of IPs (Inner pillar cells). The mosaic configuration of the reticular membrane is not typical. The stereocilia of IHCs (Inner hair cells) are not uniform and some kinocilia could be seen on the OHCs in adults. The epithelial surface of RM (Reissner’s membrane) is not smooth and no mesh could be seen on the mesothelial surface of RM. TEM.

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Insights into the biochemical and functional characterization of sortase E transpeptidase of Corynebacterium glutamicum

Biochemical Journal ◽

10.1042/bcj20190812 ◽

2019 ◽

Vol 476 (24) ◽

pp. 3835-3847 ◽

Cited By ~ 1

Author(s):

Aliyath Susmitha ◽

Kesavan Madhavan Nampoothiri ◽

Harsha Bajaj

Keyword(s):

Protein Engineering ◽

Cell Attachment ◽

Functional Characterization ◽

Protein Structures ◽

Structural Similarity ◽

Surface Proteins ◽

Sortase A ◽

Peptide Cleavage ◽

New Findings

Most Gram-positive bacteria contain a membrane-bound transpeptidase known as sortase which covalently incorporates the surface proteins on to the cell wall. The sortase-displayed protein structures are involved in cell attachment, nutrient uptake and aerial hyphae formation. Among the six classes of sortase (A–F), sortase A of S. aureus is the well-characterized housekeeping enzyme considered as an ideal drug target and a valuable biochemical reagent for protein engineering. Similar to SrtA, class E sortase in GC rich bacteria plays a housekeeping role which is not studied extensively. However, C. glutamicum ATCC 13032, an industrially important organism known for amino acid production, carries a single putative sortase (NCgl2838) gene but neither in vitro peptide cleavage activity nor biochemical characterizations have been investigated. Here, we identified that the gene is having a sortase activity and analyzed its structural similarity with Cd-SrtF. The purified enzyme showed a greater affinity toward LAXTG substrate with a calculated KM of 12 ± 1 µM, one of the highest affinities reported for this class of enzyme. Moreover, site-directed mutation studies were carried to ascertain the structure functional relationship of Cg-SrtE and all these are new findings which will enable us to perceive exciting protein engineering applications with this class of enzyme from a non-pathogenic microbe.

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