Protein constituents of the eggshell: eggshell-specific matrix proteins

In this article, we review the results of recent proteomic and genomic analyses of eggshell matrix proteins and draw attention to the impact of these data on current understanding of eggshell formation and function. Eggshell-specific matrix proteins from avian (ovocleidins and ovocalyxins) and non-avian (paleovaterin) shells are discussed. Two possible roles for eggshell-specific matrix proteins have been proposed; both reflect the protective function of the eggshell in avian reproduction: regulation of eggshell mineralization and antimicrobial defense. An emerging concept is the dual role (mineralization/antimicrobial protection) that certain eggshell matrix proteins can play.     

Noise to order

Patterns in natural systems abound, from the stripes on a zebra to ripples in a riverbed. In many of these systems, the appearance of an ordered state is not unexpected as the outcome of an underlying ordered process. Thus crystal growth, honeycomb manufacture and floret evolution generate regular and predictable patterns. Intrinsically noisy and disordered processes such as thermal fluctuations or mechanically randomized scattering generate surprisingly similar patterns. Here we discuss some of the underlying mechanisms believed to be at the heart of these similarities.     

The complete structure of ryanodine

Zusammenfassung Die Struktur des Ryanodins und die Natur der Ryanodin-Anhydroryanodin-Umlagerung wird diskutiert.     

The distribution of bilirubin in rat liver fractions

Zusammenfassung Die Bilirubinmengen in den Geweben ikterischerGunn-Ratten werden zusammen mit den in den subzellulären Anterilen vorliegenden Bilirubinmengen ikterischerGunn-Rattenlebern bestimmt. Die Bilirubinbestimmung erfolgte nach i.v. Infusion von Bilirubin in die Rattenleber: es findet sich vorwiegend im Leberzellensaft der ikterischenGunn-Ratte, verteilt sich jedoch nach Bilirubininfusion gleichmässig über alle Leberanteile. Die teils bekannten, teils bestätigten Unterschiede können durch Plasma-Eiweiss-Bindung des Bilirubins erklärt werden.

---

---

We would like to thank Professor N. H.Martin for his advice and encouragement and the British Empire Cancer Campaign for financial assistance.     

Resistance to positional noise in human vision

Human eyes are in constant and rapid motion even when observers try to maintain steady fixation. Also, the visual system has a sluggish temporal response. In combination, these two factors would be expected to blur stimuli and reduce spatial sensitivity. But observers are able to detect a difference in separation of a few seconds of arc between two closely spaced parallel lines. Here we report that even very large amounts of positional jitter of the line pair has minimal impact on this ability. This result is in marked contrast to the deterioration observed when targets are swept linearly across the retina, but is consistent with a system that must ignore oculomotor jitter. To explain these results will require a re-evaluation of current models of position coding in human vision.     

Cytoskeletal filaments of heart conducting system localized by antibody against a 55,000 dalton protein

Summary Cow heart conducting cells characteristically contain cytoplasmic intermediate-sized filaments. We report here the preparation of a specific antibody to a 55,000 dalton protein of isolated cow Purkinje fibres. Confirmation has been obtained that these filaments consist of the 55,000 dalton protein, using the indirect immunofluorescence technique. Crossreaction is seen with vascular endothelium and smooth muscle cells of various origin, suggesting close identity of different types of intermediate-sized filaments.     

Alternative exon usage selectively determines both tissue distribution and subcellular localization of the acyl-CoA thioesterase 7 gene products

Acyl-CoA thioesterases (ACOTs) catalyze the hydrolysis of acyl-CoAs to free fatty acids and coenzyme A. Recent studies have demonstrated that one gene named Acot7, reported to be mainly expressed in brain and testis, is transcribed in several different isoforms by alternative usage of first exons. Strongly decreased levels of ACOT7 activity and protein in both mitochondria and cytosol was reported in patients diagnosed with fatty acid oxidation defects, linking ACOT7 function to regulation of fatty acid oxidation in other tissues. In this study, we have identified five possible first exons in mouse Acot7 (Acot7a–e) and show that all five first exons are transcribed in a tissue-specific manner. Taken together, these data show that the Acot7 gene is expressed as multiple isoforms in a tissue-specific manner, and that expression in tissues other than brain and testis is likely to play important roles in fatty acid metabolism. Received 5 February 2007: received after revision 3 April 2007; accepted 19 April 2007