Elizabeth A. Koch

A New Blood Factor, s, Allelic to S

Summary A new blood factor, s, is described with the aid of an antibody produced by transplacental isoimmunization. Evidence is presented to show its genetic relationship to the S factor, which is probably linked to the M and N system.

Hagfish Skin and Slime Glands

The scaleless hagfish employs two modes of secretion, holocrine by the slime glands and to a lesser extent merocrine by the epidermis for release of its voluminous viscous exudate. In both cases, large organized entities of intermediate filaments (IFs) are requisite participants. In the epidermis, each small mucous cell contains an IF-rich, basket-like structure (‘capsule’) which serves to compartmentalize the mucin-rich secretory vesicles within the apical region for subsequent release. Each epidermal thread cell contains at least one large IF-biopolymer (‘thread’) which may affect both the physical properties of the epidermis and the epidermal exudate. By contrast, the single IF-rich thread biopolymer precisely localized in each gland thread cell, interacts synergistically with mucins from the gland mucous cells to loosely organize water into a viscous mass of slime (stage 1), which, after physical perturbation, forms even more massive IF-aggregates (‘cables’) accompanied by the release of water (stage 2). The massive gland thread exhibits a linearly aligned IF/microtubule motif and is destined for extracellular export to function in an aqueous environment. Comparisons of the hagfish thread IF-polypeptide sequences (γ and α, with high threonine-contents) reported herein show no preferred identity to any other type of sequenced IF including those from higher vertebrates, a cephalochordate and invertebrates. Inasmuch as several keratin traits exist, we have characterized γ and α as homologues of type I and II epidermal keratins, respectively.