Trehalose is a disaccharide with important functional properties. Although these properties have been recognized for many years, trehalose was not produced on an industrial scale. Recently, a novel enzymatic system for the production of trehalose was developed, and the cost has been dramatically reduced enough to permit widespread application. In the present study, the stabilization mechanism of unsaturated fatty acids by trehalose was found. Furthermore, possible suppressive effects of trehalose on osteoporosis development emerged from our experiments. Trehalose is also expected to be used for various applications in the fields of cosmetics and pharmaceuticals. PROPERTIES OF TREHALOSETrehalose is a disaccharide composed of two glucose molecules bound by an alpha, alpha-1, 1 linkage. Since the reducing end of a glucosyl residue is connected with the other, trehalose has no reducing power. Trehalose is widely distributed in nature. It is known to be one of the sources of energy in most living organisms and can be found in many organisms, including bacteria, fungi, insects, plants, and invertebrates. Mushrooms contain up to 10-25 % trehalose by dry weight. Furthermore, trehalose protects organisms against various stresses, such as dryness, freezing, and osmopressure. In the case of resurrection plants, which can live in a dry state, when the water dries up, the plants dry up too. However, they can successfully revive when placed in water. The anhydrobitic organisms are able to tolerate the lack of water owing to their ability to synthesize large quantities of trehalose, and the trehalose plays a key role in stabilizing membranes and other macromolecular assemblies under extreme environmental conditions. The properties of trehalose are shown in Table 1. Its relative sweetness is 45 % of sucrose. Trehalose has high thermostability and a wide pH-stability range. Therefore, it is one of the most stable saccharides. When 4 % trehalose solutions with 3.5 to 10 pH were heated at 100 °C for 24 h, no degradation of trehalose was observed in any case. Because of nonreducing sugar, this saccharide does not show Maillard reaction with amino compounds such as amino acids or proteins. Its particular physical features make it an extremely attractive substance for industrial applications. Furthermore, this saccharide shows good sweetness like sucrose, and in the food industry, this saccharide is used as a sweetener.

Six copies of insertion elements accumulate in the subtelomeric region immediately proximal to the telomeric repeats on Chlorella chromosome I. The elements, designated Zepps, bear the characteristic features of non‐viral (LINE‐like) retrotransposons, including a poly(A) tail, 5′‐truncations, a retroviral reverse transcriptase‐like ORF and flanking target duplications. Detailed sequence analysis of the Chlorella subtelomeric region revealed a novel mechanism of Zepp transposition; successive insertions of each Zepp element into another Zepp as a target, leaving a tandem array of their 3′‐regions with poly(A) tracts facing toward the centromere. Only the most distal Zepp copy was inverted to connect its poly(A) tail with the telomeric repeats. A similar Zepp cluster but without the telomeric repeats was also found at the terminus of another Chlorella chromosome. These structures contrast with that proposed for the addition of HeT‐A and TART elements to Drosophila telomeres. Expression of Zepp elements is induced by heat shock treatment. Possible roles of the subtelomeric retrotransposons in formation and maintenance of telomeres are discussed.

Chaperonin CCT containing t-complex polypeptide 1 is a cytosolic molecular chaperone that assists in the folding of actin, tubulin, and other proteins and is a member of the 60-kDa heat shock protein (Hsp60) family. We examined antibody titers against human CCT and other Hsp60 family members in the sera of patients with rheumatic autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematodes, Sjögren syndrome, and mixed connective tissue disease. Autoantibody titers against not only human mitochondrial Hsp60 but also CCT were significantly higher in the sera of patients with rheumatic autoimmune diseases than in healthy control sera. Although immunoglobulin G (IgG) titers against Escherichia coli GroEL were high in all the groups of sera tested, no significant differences in anti-GroEL responses were detected between patients and healthy controls. IgG titers against mycobacterial Hsp65 showed a similar pattern to titers of autoantibodies recognizing GroEL. Immunoabsorption experiments demonstrated that most of the autoantibodies recognizing CCT were cross-reactive with mitochondrial Hsp60, E coli GroEL, and mycobacterial Hsp65. Although most of the anti-Hsp60 IgG recognized CCT, anti-GroEL (or antimycobacterial Hsp65) IgG contained antibodies specific for GroEL (or mycobacterial Hsp65) in addition to antibodies cross-reactive with CCT and Hsp60. Results from immunoblot analyses, together with weak (15% to 20%) amino acid sequence identities between CCT and the other Hsp60 family members, suggested that CCT-reactive autoantibodies recognize conformational epitopes that are conserved among CCT and other Hsp60 family members.

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By using a plaque assay with the unicellular green alga Chlorella sp. strain NC64A as a host, viruses were screened from natural pond waters collected in Kyoto and Higashi-Hiroshina, Japan. From some samples tested, two kinds of plaques, large (+ = 6 to 10 mm) and small (4 = 2 to 3 mm), were detected with various frequencies. The frequency of plaques in each of the water sources was seasonal; generally, it reached a peak value (8,000 PFU/ml) in May and gradually decreased to the limit of detection (<1) in November before increasing again in early spring. Electron microscopy revealed that the purified and negatively stained viruses were very large (125 to 200 nm) icosahedral particles. The genome isolated from these particles was always a linear double-stranded DNA of 340 to 370 kbp. Electrophoresis patterns of the DNA fragments produced by digestion with restriction enzymes differed considerably from plaque to plaque, even for plaques from the same water source. However, Southern hybridization showed strong homology among all of the virus DNAs tested, indicating relatedness of those viruses. A possible use of the Chlorella virus assay system to monitor the natural population of algal cells and water quality is discussed.