The green microalga Lobosphaera incisa harbours an arachidonate 15S-lipoxygenase.

The green microalga Lobosphaera incisa is an oleaginous eukaryotic alga that is rich in arachidonic acid (20:4). Being rich in this polyunsaturated fatty acid (PUFA), however, makes it sensitive to oxidation. In plants, lipoxygenases (LOXs) are the major enzymes that oxidise these molecules. Here, we describe, to our best knowledge, the first characterisation of a cDNA encoding a LOX (LiLOX) from a green alga. To obtain first insights into its function, we expressed it in E. coli, purified the recombinant enzyme and analysed its enzyme activity. The protein sequence suggests that LiLOX and plastidic LOXs from bryophytes and flowering plants may share a common ancestor. The fact that LiLOX oxidises all PUFAs tested with a consistent oxidation on the carbon n-6, suggests that PUFAs enter the substrate channel through their methyl group first (tail first). Additionally, LiLOX form the fatty acid hydroperoxide in strict S configuration. LiLOX may represent a good model to study plastid LOX, because it is stable after heterologous expression in E. coli and highly active in vitro. Moreover, as the first characterised LOX from green microalgae, it opens the possibility to study endogenous LOX pathways in these organisms.

Original semiologic standardized evaluation of stratum corneum hydration by Diagnoskin stripping sample.

In a normal and healthy skin, the regular elimination of the superficial corneocytes, called desquamation, is a fundamental physiologic process intended to protect the barrier function of the skin. This invisible loss of corneocytes, individually or in small groups, is incessantly compensated by the divisions of the proliferative layer and the upward cellular maturation in order to maintain the harmonious renewal of the epidermis and the integrity of the stratum corneum. The harmony of this desquamation process is intimately conditioned by a sufficient hydration of the stratum corneum: (i) an abnormal desquamation leads to a disruption of the water barrier function and consequently to a dehydration tendency of the stratum corneum, and (ii) a cutaneous dryness (whatever the cause) is able to disturb the desquamation process. Protecting the water content of the stratum corneum has always been a major preoccupation of the cosmetic industry scientists. Consequently, the moisturizing properties of a cosmetic product are objectively measured by various explorations directly targeted on the hydration (corneometry) and on the level of the water barrier function (transepidermal water loss (TEWL) measurements), which depends directly on the skin hydration state. This intimate linkage of the desquamation process and the water content of the stratum corneum enable us to suggest an indirect assessment of the hydration from a direct study of the desquamation by examining a skin-stripping sample (D-Squames) by an optical microscope (linked to a computer). We will describe this already known technique and mainly its new and unpublished semiologic exploitation, named Diagnoskin, whose advantages are its simplicity and its reproducibility particularly interesting in the case of sequential appraisal of dermatologic or cosmetic treatments.

[Trichothiodystrophy]. / Trichothiodystrophie.

Trichothiodystrophy is a congenital dysplasia of hairs characterized by: a pathognomonic image of the hair shaft under polarized light (the hair is plaited with alternately dark and light oblique bands) and trichoschisis with a clear-cut break; a deficiency of sulphurated aminoacids in the hair. We report a case where trichothiodystrophy was associated with abnormalities of the nails, teeth and eyes, growth and mental retardation, neurological syndrome and hypogonadism. From this case and a review of the cases published so far the following points emerge: 1. Congenital abnormalities of the neuroectodermal system are frequent. They include: skin lesions, such as ichthyosis, photosensitivity and atopic eczema; ungueal dysplasia; dysmorphic syndrome; growth and mental retardation; hypogonadism; neurological and ophthalmic abnormalities. 2. The condition seems to be transmitted as an autosomal recessive trait. A common element, dysplasia, enables us to include in the same nosological group as trichothiodystrophy a number of other pathological conditions, viz.: syndromes hitherto described under various names but almost identical, such as Brown's syndrome and BIDS syndrome (brittle hair, intellectual deficit, decreased fertility, small stature); IBIDS and PIBIDS syndromes which, in addition to the former, comprise ichthyosis and photosensitivity, as well as Tay's syndrome (characterized by the presence in all cases of ichthyosis associated with hair dysplasia); and perhaps some anecdotic cases with either a pathognomonic image under polarized light or a suggestive biochemical profile. Finally, since typical trichothiodystrophy has been reported in patients with Siemens' syndrome or with Marviesco-Sjögren syndrome, these two syndromes may perhaps also be classified in the same category, as borderline forms of the disease.