Photosynthesis–nitrogen relationships in species at different altitudes on Mount Kinabalu, Malaysia

In situ photosynthetic nitrogen-use efficiency (PNUE, photosynthetic capacity per unit leaf nitrogen) was investigated in species that commonly distributed at different altitudes (600–3700m above sea level) on Mount Kinabalu. Photosynthetic nitrogen-use efficiency was lower in species at higher altitudes, with a mean PNUE at 3700m being one-third as large as that at 600m. This difference in PNUE was larger than that explained by the biochemical response to lower air pressures only. Across altitudes a negative correlation between ¹³C abundance (¹³C) and PNUE was found. Species at higher altitudes tended to have higher ¹³C, suggesting that they had a lower conductance for CO₂ diffusion from the air to chloroplasts. The lower conductance might be responsible for the lower PNUE in species at higher altitudes. Although leaf nitrogen content per unit area tended to be higher at higher altitudes, it did not seem to contribute to increasing photosynthetic rates. Thus, the idea that a higher nitrogen content at higher altitudes is a compensation for a lower PNUE was not supported. In contrast to the large difference in PNUE among altitudes, PNUE tended to converge within a narrow range among species growing at the same altitude.     

The role of CD98 in astrocytic neoplasms

The high expression of CD98 was reported in some normal tissues, including blood brain barrier, activated lymphocytes, the basal layer of skin, proximal tubles of kidney, placenta, testis and a wide variety of tumors. The CD98 complex consists of an 80-85kD heavy chain (4F2hc/FRP-1) and a 40-45kD light chain. CD98hc, 4F2hc, and FRP-1 are the same glycosylated protein each other and define antigenicity of CD98. LAT1, the sodium-independent L-type amino acid transporter 1, has been identified as a light chain of the CD98 heterodimer from C6 glioma cells. LAT1 also corresponds to TA1, an oncofetal antigen that is expressed primarily in fetal tissues and cancer cells such as glioma cells. Increased LAT1 expression was found in various malignancies including human gliomas. Several studies implicated the important role of LAT1 and 4F2hc in malignant transformation and carcinogenesis. The LAT1-CD98 pathway may represent a unique therapeutic target for cancer intervention.     

Establishment and characterization of a lymphoepithelial-like carcinoma cell line (HUUCLEC) derived from the human uterine cervix

A cell line designated HUUCLEC was established from a human uterine cervical lymphoepithelial carcinoma obtained from a 61-year-old Japanese woman. The cell line has grown slowly without interruption and serial passages were successively carried out 60 times within 3 years. The cultured cells were spindle or round in shape, showing anaplastic and pleomorphic features, a pavement cell arrangement and multilayering without contact inhibition. The population doubling time of the HUUCLEC line was 72 hours while the chromosomal number varied widely and showed aneuploidy. The modal chromosomal number was stable at the triploid range and marker chromosomes were present; the Ebstein-Barr virus was absent in the cultured cells.     

Isolation and characterization of the genes encoding two metalloproteases (MprI and MprII) from a marine bacterium, Alteromonas sp. strain O-7

An extracellular alkaline metalloprotease (MprI) from Alteromonas sp. strain O-7 was purified and characterized. The molecular mass of the purified enzyme was estimated to be 56 kDa by SDS-PAGE. The optimum pH and temperature were pH 10.0 and 60 degrees C, respectively. The gene (mprI) encoding MprI was cloned and its nucleotide sequence was analyzed. The deduced amino acid sequence of MprI showed significant similarity to metalloproteases classified into the thermolysin family. Furthermore, sequence analysis showed that another metalloprotease (MprII)-encoding gene was located downstream from mprI. The deduced amino acid sequence of MprII showed high similarity to metalloproteases of the aminopeptidase family. Similar repeated C-terminal extensions were found in both MprI and MprII.     

Biotransformation of L-lysine to L-pipecolic acid catalyzed by L-lysine 6-aminotransferase and pyrroline-5-carboxylate reductase

The enzyme involved in the reduction of delta1-piperideine-6-carboxylate (P6C) to L-pipecolic acid (L-PA) has never been identified. We found that Escherichia coli JM109 transformed with the lat gene encoding L-lysine 6-aminotransferase (LAT) converted L-lysine (L-Lys) to L-PA. This suggested that there is a gene encoding "P6C reductase" that catalyzes the reduction of P6C to L-PA in the genome of E. coli. The complementation experiment of proC32 in E. coli RK4904 for L-PA production clearly shows that the expression of both lat and proC is essential for the biotransformation of L-Lys to L-PA. Further, We showed that both LAT and pyrroline-5-carboxylate (P5C) reductase, the product of proC, were needed to convert L-Lys to L-PA in vitro. These results demonstrate that P5C reductase catalyzes the reduction of P6C to L-PA. Biotransformation of L-Lys to L-PA using lat-expressing E. coli BL21 was done and L-PA was accumulated in the medium to reach at an amount of 3.9 g/l after 159 h of cultivation. It is noteworthy that the ee-value of the produced pipecolic acid was 100%.     

Radical scavenging activities of niacin-related compounds

We investigated whether niacin-related compounds had radical-scavenging activity by electron spin resonance methods. Many compounds, but not trigonelline, had radical-scavenging activity against hydroxyl radicals. However, for the nitric oxide radical and 1,1-diphenyl-2-picrylhydrazyl radical, only nicotinic acid hydrazide and isonicotinic acid hydrazide had scavenging activities. These results suggest that the moiety of hydrazide might have an important role in scavenging abilities of various radicals.     

Spectroscopic evidence that salicylic acid converts a temporally inactivated form of horseradish peroxidase (compound III) to the irreversibly inactivated verdohemoprotein (P-670)

We obtained spectroscopic evidence in support of salicylate-dependent inactivation of horseradish peroxidase-C. Addition of salicylate to the enzyme arrested at a temporal inactive state (Compound III) in the presence of H2O2, resulted in rapid and irreversible inactivation of the enzyme yielding verdohemoproteins (P-670). Multiple roles for salicylate in peroxidase-catalyzed reactions are discussed.     

Histochemical analysis of macrophage migration inhibitory factor in psoriasis vulgaris

Psoriasis is a persistent cutaneous disease characterized by skin inflammation and infiltration of immunocytes such as lymphocytes and monocytes/macrophages, concomitant with abnormal epidermal hyperproliferation. We previously showed that the serum level of macrophage migration inhibitory factor (MIF) and its production by peripheral blood mononuclear cells of patients with psoriasis were closely correlated with the severity of clinical symptoms; however, the precise role of MIF in psoriatic epidermis remains to be clarified. The current study was carried out to elucidate the possible involvement of MIF in psoriasis, using immunohistochemistry and in situ hybridization. In contrast to elevated serum MIF in psoriasis, MIF-positive staining in the lesional psoriatic epidermis was significantly decreased, as demonstrated by immunohistochemical analysis using an anti-MIF antibody. Consistent with this finding, we found, by in situ hybridization, that MIF mRNA concomitantly decreased in the psoriatic lesions. Although the reason for the different MIF levels in the psoriatic epidermis and in the circulation remains unknown, it is hypothesized that MIF, a potential growth factor, might be decreased in psoriatic lesions to counterregulate the abnormal epidermal proliferation caused by dysregulation of cytokines and growth factors.     

<Emphasis Type="Italic">HrNodal</Emphasis>, the ascidian <Emphasis Type="Italic">nodal</Emphasis>-related gene,is expressed in the left side of the epidermis,and lies upstream of <Emphasis Type="Italic">HrPitx</Emphasis>

The nodal-related genes are well known for their fundamental roles during vertebrate development, including mesoderm induction, neural induction, and left-right axis formation, as several nodal-related genes show left-sided expression in mesodermal lineages. We have isolated the first non-vertebrate nodal-related gene, HrNodal, from the ascidian Halocynthia roretzi. During the late cleavage and gastrula stages, HrNodal is transiently and bilaterally expressed in several different cell lineages. Expression at the tailbud stage is observed asymmetrically in the left side, but unexpectedly only in the epidermis of the embryo. We also demonstrate the relationship of HrNodal with HrPitx, a Halocynthia homologue of the Pitx2 gene. HrNodal overexpression results in the disturbance of left-sided HrPitx expression. Our results demonstrate that left-right specification during ascidian embryogenesis involves the HrNodal gene, and that the left-sidedness of the expression is evolutionarily conserved throughout the chordate clade.