Present status and conservation of the markless forms of stream-resident masu salmon Oncorhynchus masou (the so-called ‘iwame’) in Japanese mountain streams

As a markless form of stream-resident masu salmon (Oncorhynchus masou), the so-called ‘iwame,’ which can be distinguished from the sympatric normal form of the salmon by their plain body pattern, has been previously reported among seven local populations (A–G) in Japanese mountain streams. In the present study, all populations but B (where any information is entirely missing) were surveyed in a snorkeling survey (detection rate: 34.7%) in 2005 to elucidate the recent conditions of the markless forms. The ratios of the markless forms were 13.0% (9/69), 0.0% (0/364), 5.6% (68/1,205), 0.8% (1/132), 0.0% (0/1,181) and 64.6% (155/240) in A, C, D, E, F and G, respectively. Markless forms might indeed be already extinct in C and F where the stocking of non-native hatchery individuals has been carried out extensively. The same survey was repeated in D in 2009: the markless ratio had significantly decreased to 2.4% (19/783), although the reason for this was unknown. In D, the ratio of the markless form was higher in the mainstream as opposed to the tributaries in both 2005 and 2009, which might imply that the habitat of the markless form differs from that of the normal form.     

Photoperiodic modification of negative and positive feedback effects of oestradiol on LH secretion in ovariectomized goats

Ovariectomized Shiba goats carrying an oestradiol implant (4-10 pg/ml) were kept under a short-day light regimen (10L:14D; Group 1, N = 4) or a long-day regimen (16L:8D; Group 2, N = 4). Plasma LH concentrations were lower (P less than 0.05) in Group 2 than in Group 1 between Days 40 and 200, suggesting an enhanced negative feedback effect of oestradiol on LH secretion under a long-day regimen. On Days 30, 60, 100, 149 and 279, an LH surge was induced by i.v. infusion of oestradiol for 48 h; the infusion rate was gradually increased from 0.5 (0 h) to 4.1 (48 h) micrograms/h, thereby mimicking the preovulatory increase of oestradiol secretion. The duration and magnitude of the induced LH surge were indistinguishable between the groups. The latency from the onset of oestradiol infusion to the LH surge was relatively constant in Group 1, 41.1 +/- 0.9 h (mean +/- s.e.m., n = 17) but was shorter in Group 2 (19.7 +/- 3.7 h, P less than 0.05) on Day 149; less oestradiol was therefore required for induction of the LH surge (27.4 vs 89.7 micrograms, P less than 0.01), suggesting an increased sensitivity to the oestradiol positive feedback under a long-day regimen. These results might be interpreted to indicate that the hypothalamic-pituitary axis of the goat becomes hypersensitive to the positive as well as the negative feedback effect of oestradiol under long-day conditions.     

Amino acid substitution in the C-terminal arm domain of HU-2 results in an enhanced affinity for DNA.

Three mutants of the Escherichia coli hupA gene, encoding the HU-2 protein, were constructed by synthetic oligodeoxyribonucleotide-directed, site-specific mutagenesis on M13mp18 vectors. The resulting HupAN10, HupAN11 and HupAN12 proteins contained Thr59-->Lys, Gln64-->Lys and Asn53-->Arg substitutions, respectively. These amino acid (aa) changes increased the positive charge of the N-terminal half of the two-strand, antiparallel beta-ribbon of the arm structure, which is believed to be a domain for DNA binding. The three mutant proteins bound to DNA more tightly than wild-type HU-2, and their affinities for DNA increased in the order of HupAN10, HupAN11, HupAN12. The mutant proteins showed a slightly increased HU activity for supporting Mu phage development. A mutant HU-2 protein with increased basicity, but with an altered aa sequence in the arm region due to a frameshift mutation, was also constructed. This mutant protein showed a reduced affinity to DNA and was unable to support Mu growth, suggesting that a unique aa sequence of the arm domain, rather than mere basicity of this domain, is required for efficient binding to DNA.     

The Duffy binding protein as a key target for a Plasmodium vivax vaccine: lessons from the Brazilian Amazon

Plasmodium vivax infects human erythrocytes through a major pathway that requires interaction between an apical parasite protein, the Duffy binding protein (PvDBP) and its receptor on reticulocytes, the Duffy antigen/receptor for chemokines (DARC). The importance of the interaction between PvDBP (region II, DBPII) and DARC to P. vivax infection has motivated our malaria research group at Oswaldo Cruz Foundation (state of Minas Gerais, Brazil) to conduct a number of immunoepidemiological studies to characterise the naturally acquired immunity to PvDBP in populations living in the Amazon rainforest. In this review, we provide an update on the immunology and molecular epidemiology of PvDBP in the Brazilian Amazon - an area of markedly unstable malaria transmission - and compare it with data from other parts of Latin America, as well as Asia and Oceania.     

Correction to: Resistance Mechanism in a Terbinafine-Resistant Strain of Microsporum canis

Mycopathologia - In the initial online publication, the name of author Hock Siew Han was given incorrectly as Han Hock Siew. The original article has been corrected.     

SV40LT highly mutates and immortalizes two fibroblast strains from patients with Wilms' tumor.

In order to analyze in detail the process of immortalization of human cells, SV40LT was introduced into two chromosome 11p- fibroblast strains from Wilms' tumor patients. Both fibroblasts, hereafter referred to as CM1 and CM2, displayed the mutant phenotype in the crisis stage of cellular aging. In comparison to a control fibroblast, the density of the CM1 strain was abnormally high while the crisis period of the CM2 strain was abnormally long. The CM1 immortalization was 7 times greater than the control and the CM2 strain had the highest frequency of immortalization, 7 times greater than the CM1. These findings indicate that genes associated with chromosome 11p- may be involved in the immortalization of human cells. During their abnormal crisis periods, the cells derived from the patients with Wilms' tumor showed an extremely high frequency of chromosomal aberrations and mutations (6TGs --> 6TGr). These results indicate that when the growth-arrested cells from Wilms' patients are induced to grow with the introduction of SV40LT at the crisis stage they are highly mutable, resulting in their immortalization in vitro.