Albinism and mouse behaviour

This study examines the behavioural effects of the gene for albinism (c-locus) in mice. For this purpose, homozygous albino mutants were compared with heterozygous pigmented mice, all males, in three experimental situations: 1. In order to obtain a general picture of the behavioural phenotype, the frequencies of 22 acts and postures displayed by solitary mice in a large observation cage were observed directly. 2. Using a platform that could be fixed at different heights, the levels and latencies of descent were recorded for the two genotypes. 3. In a pole-climbing test, the climbing latencies of the animals were measured. These experiments indicated that albinos show more fear of heights (are more acrophobic) than wild-type mice. Their visual exploration of space appears to be about normal. The problem of the causation of this acrophobia is discussed.In one single respect (climbing latency) the mutants turned out to be more variable than the controls, a finding which might be explained in terms of a weaker canalization of their phenotype.     

Human Albinism and Animal Models of Albinism

Ten phenotypic forms of oculocutaneous albinism (OCA) and four forms of ocular albinism (OA) have been identified in man. All have optic neuronal decussation defects at the optic chiasm. Thus any proposed animal model for these disorders must share optic neuronal decussation defects in addition to hypopigmentation. Three, tyrosinase-negative (ty-neg), yellow mutant (ym), and platinum (pt), OCA appear to be allelic in humans. Two, ty-neg and pt, OCA appear to be analogous to c-locus mutants c/c and c^p/c^p in mice, but no homologue is known in mice for ym OCA. Tyrosinase-positive (ty-pos) OCA, which is nonallelic with ty-neg OCA, shares many morphological and biochemical features with pink-eyed mice. Chediak-Higashi syndrome (CHS) and Hermansky-Pudlak syndrome (HPS) appear to be due to genes acting extrinsic to the melanin pathway. CHS is homologous with beige in mice. HPS was investigated in northwestern Puerto Rico, where it affects approximately 1 in 2,000 persons. Approximately 68% of 37 deceased HPS patients died from sequelae of ceroid storage disease, restrictive lung disease between ages 35 and 46 years (43%), and granulomatous colitis (8%) or hemorrhage (16%). The most accurate and consistent diagnostic feature of HPS is lack of platelet dense bodies. HPS patients with ceroid storage disease had high urinary levels of long-chain isoprenoid alcohols, dolichols, similar to that seen in the neuronal-ceroid lipofuscinoses (Batten disease). Dolichols are constituents of lysosomes, and their elevation in HPS suggests that this syndrome carries a lysosomal defect. There is no degradative pathway for ceroid and dolichols, which are eliminated by exocytosis. The exocytic process is thought to involve a thioendoproteinase. Pale-ear mice have been proposed as a model for HPS; their platelets lack dense bodies, and they are depigmented. Leupeptin, a thioendoproteinase inhibitor, administered to 100-day-old pale-eared and black wild-type C57 mice for 10 days resulted in the accumulation of ceroid in tissues in the same pattern as that in HPS, but granulomas of gut or fibrosis of lungs were not seen. Determinations of homology between mice and men at the molecular level is now possible with the isolation of mouse tyrosinase by Yamamoto et al. and isolation by Kwon et al. of human tyrosinase mapping at the c-locus in mice.     

Albinism in barley androgenesis

Androgenesis is highly useful for plant breeding, significantly reducing breeding cycle times, as well as in a wide range of biological research. However, for widespread use this process must be efficient. Despite several decades of research on the phenomenon of androgenesis, many processes involved are obscure and there is much to be understood about androgenesis. One of the problems inherent in androgenesis, and reducing its efficiency, is albinism. This article reviews albinism in barley anthers and microspores in vitro cultures. Of special interest is the fate of plastids throughout androgenesis, which is important at several levels, including the genes responsible for driving the green-to-albino ratios. We also summarize the external factors that reduce the incidence of albino plants that are regenerated via androgenesis.     

Tyrp1 and Oculocutaneous Albinism Type 3

Tyrosinase‐related protein 1 (Tyrp1) is a melanocyte‐specific gene product involved in eumelanin synthesis. Mutations in the mouse Tyrp1 gene are associated with brown pelage, and in the human TYRP1 gene with oculocutaneous albinism type 3 (OCA3). In the murine system, Tyrp1 expresses significant dihydroxyindole carboxylic acid oxidase (i.e. DHICA oxidase) activity. However, in humans, TYRP1 is enigmatic in that despite extensive efforts focused on the study of its function, its actual role in the human melanocyte is still unclear. There is mounting evidence demonstrating that in addition to its role in eumelanin synthesis, Tyrp1 is involved in maintaining stability of tyrosinase protein and modulating its catalytic activity. Tyrp1 is also involved in maintenance of melanosome ultrastructure and affects melanocyte proliferation and melanocyte cell death. The current review is an attempt to consolidate our understanding of the role of Tyrp1 in the melanocyte.     

The mouse: genetics meets behaviour

Genetic studies in the mouse are important in the elucidation of molecular pathways that underlie behaviour. The advantages of the mouse for behavioural studies include an extensive array of genetic technologies and an elaborate behavioural repertoire that can be used to create models of human disease. This review discusses the relative advantages of forward and reverse genetic approaches to studying the genetic basis of behaviour in the mouse, and the complexities that behavioural studies need to address, such as phenotypic variability, genetic background effects and pleiotropy.     

白化病的遗传流行病学研究

本文应用分离分析和血缘分析方法,对山东省１００余万人群遗传病调查中发现的３７个白化病核心家系进行了分析。结果表明：白化病存在遗传异质性,为多基因常染色体隐性遗传,最小基因数为８,平均基因频率为０．００２３,群体中致病基因携带者频率为０．０３８３;近亲结婚大大提高白化病的患病率。     

Albinism as a marker in Tetranychus pacificus

An albino male was discovered in a population of Tetranychus pacificus, as a result of spontaneous mutation. It appeared that this albinism was recessive and under monogenic control. A maternal effect was demonstrated. The albinism is a suitable marker for all stages of development in this mite species.

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Albinismus als genetische markierung bei tetranychus pacificus

Zusammenfassung In einer Population von Tetranychus pacificus wurde als Ergebnis spontaner Mutation ein albinotisches Männchen entdeckt. Es wird erwiesen dass dieser Albinismus rezessiv und monogenetisch beding ist. Ein mütterlicher Effekt war nachzuweisen. Der Albinismus ist eine geeignete genetische Markierung für alle Entwicklungsstadien bei dieser Spinnmilben-Art.