The discovery of <i>Isocrinus</i> cf. <i>robustus</i> from the Lias Group (Lower Jurassic) near Dunrobin Castle, Sutherland, Scotland

A single stem section (pluricolumnal) belonging to a post-Palaeozoic crinoid (sea lily) is reported from a small outcrop of Lower Jurassic Lias Group strata exposed in low cliff near Dunrobin Castle. This is the first Jurassic crinoid recorded from Eastern Scotland and the small fragment has enough diagnostic characters to be assigned to the species Isocrinus cf. robustus; a crinoid found commonly in the Lower Jurassic of England. The Scottish form collected has unusual morphology that is atypical of the genus

Meiotic Recombination: The Essence of Heredity.

The study of homologous recombination has its historical roots in meiosis. In this context, recombination occurs as a programmed event that culminates in the formation of crossovers, which are essential for accurate chromosome segregation and create new combinations of parental alleles. Thus, meiotic recombination underlies both the independent assortment of parental chromosomes and genetic linkage. This review highlights the features of meiotic recombination that distinguish it from recombinational repair in somatic cells, and how the molecular processes of meiotic recombination are embedded and interdependent with the chromosome structures that characterize meiotic prophase. A more in-depth review presents our understanding of how crossover and noncrossover pathways of meiotic recombination are differentiated and regulated. The final section of this review summarizes the studies that have defined defective recombination as a leading cause of pregnancy loss and congenital disease in humans

The Synthesis and NMR Study of N6', N9-Octa-methylenepurine Cyclophane

N6', N9-Octamethylenepurine cyclophane was synthesized to act as a ¹H NMR probe for the study of the diamagnetic anisotropy about the adenine system. The title compound was formed from 6-chloropurine and cyclooctanone using two variations of the same general approach. The ¹H NMR studies resulted in the assignment and identification of each proton resonance. As a method of confirming the assignments, nuclear Overhauser enhancement studies as well as conformational analysis using X-ray crystallography were completed. Upon correlation of the proton magnetic resonance spectrum with the structure of the title compound, an attempt was made to use a model calculation to determine the diamagnetic shielding anisotropy of adenine by comparison with the methylene proton chemical shifts. Finally, in an effort to further characterize the diamagnetic shielding anisotropy about adenine, a homolog to the title compound, N6',N9-Nonamethylenepurine cyclophane, was synthesized.Doctor of Philosophy (PhD

Mapping meiotic breaks: Spo11 oligonucleotides precisely mark the spots

Initiation sites for meiotic recombination have now been precisely mapped across the budding yeast genome using a widely applicable deep-sequencing approach

Biosynthesis of the modified tetrapyrroles: the pigments of life

Modified tetrapyrroles are large macrocyclic compounds, consisting of diverse conjugation and metal chelation systems and imparting an array of colors to the biological structures that contain them. Tetrapyrroles represent some of the most complex small molecules synthesized by cells and are involved in many essential processes that are fundamental to life on Earth, including photosynthesis, respiration, and catalysis. These molecules are all derived from a common template through a series of enzyme-mediated transformations that alter the oxidation state of the macrocycle, and also modify its size, side chain composition, and the nature of the centrally chelated metal ion. The different modified tetrapyrroles include chlorophylls, hemes, siroheme, corrins (including vitamin B12), coenzyme F430, heme d1 and bilins. After nearly a century of study, almost all of the more than 90 different enzymes that synthesize this family of compounds are now known, and expression of reconstructed operons in heterologous hosts has confirmed that most pathways are complete. Aside from the highly diverse nature of the chemical reactions catalyzed, an interesting aspect of comparative biochemistry is to see how different enzymes and even entire pathways have evolved to perform alternative chemical reactions to produce the same end products in the presence and absence of oxygen. Although there is still much to learn, our current understanding of tetrapyrrole biogenesis represents a remarkable biochemical milestone that is summarized in this review

Centrosome dysfunction associated with somatic expression of the synaptonemal complex protein TEX12

The synaptonemal complex (SC) is a supramolecular protein scaffold that mediates chromosome synapsis and facilitates crossing over during meiosis. In mammals, SC proteins are generally assumed to have no other function. Here, we show that SC protein TEX12 also localises to centrosomes during meiosis independently of chromosome synapsis. In somatic cells, ectopically expressed TEX12 similarly localises to centrosomes, where it is associated with centrosome amplification, a pathology correlated with cancer development. Indeed, TEX12 is identified as a cancer-testis antigen and proliferation of some cancer cells is TEX12-dependent. Moreover, somatic expression of TEX12 is aberrantly activated via retinoic acid signalling, which is commonly disregulated in cancer. Structure-function analysis reveals that phosphorylation of TEX12 on tyrosine 48 is important for centrosome amplification but not for recruitment of TEX12 to centrosomes. We conclude that TEX12 normally localises to meiotic centrosomes, but its misexpression in somatic cells can contribute to pathological amplification and dysfunction of centrosomes in cancers

Thalidomide upper limb embryopathy - : pathogenesis, past and present management and future considerations

Open Access via the Sage AgreementPeer reviewedPublisher PD