Variability of uterine cervical anatomy in the white-tailed gnu (Connochaetes gnou)

Examination of the reproductive anatomy of six female white-tailed gnu revealed duplex uterus with varying degrees of cervical division. The division ranged from 36 to 100% of the length of the cervix, with one animal exhibiting double external ossa. This variability in reproductive anatomy could be important in artificial insemination or embryo transfer procedures in this species.     

Expression and characterization of a functional human insulin-like growth factor I receptor

Stable transfectants of Chinese hamster ovary (CHO) cells were developed that expressed the protein encoded by a human insulin-like growth factor I (IGF-I) receptor cDNA. The transfected cells expressed approximately 25,000 high affinity receptors for IGF-I (apparent Kd of 1.5 X 10(-9) M), whereas the parental CHO cells expressed only 5,000 receptors per cell (apparent Kd of 1.3 X 10(-9) M). A monoclonal antibody specific for the human IGF-I receptor inhibited IGF-I binding to the expressed receptor and immunoprecipitated polypeptides of apparent Mr values approximately 135,000 and 95,000 from metabolically labeled lysates of the transfected cells but not control cells. The expressed receptor was also capable of binding IGF-II with high affinity (Kd approximately 3 nM) and weakly recognized insulin (with about 1% the potency of IGF-I). The human IGF-I receptor expressed in these cells was capable of IGF-I-stimulated autophosphorylation and phosphorylation of endogenous substrates in the intact cell. This receptor also mediated IGF-I-stimulated glucose uptake, glycogen synthesis, and DNA synthesis. The extent of these responses was comparable to the stimulation by insulin of the same biological responses in CHO cells expressing the human insulin receptor. These results indicate that the isolated cDNA encodes a functional IGF-I receptor and that there are no inherent differences in the abilities of the insulin and IGF-I receptors to mediate rapid and long term biological responses when expressed in the same cell type. The high affinity of this receptor for IGF-II also suggests that it may be important in mediating biological responses to IGF-II as well as IGF-I.     

Enzymatic mechanism for the hydrolysis of 5,10-methenyltetrahydropteroylglutamate to 5-formyltetrahydropteroylglutamate by serine hydroxymethyltransferase.

Serine hydroxymethyltransferase in the presence of glycine catalyzes the hydrolysis of (6R)-5,10-methenyltetrahydropteroylpolyglutamate to (6S)-5-formyltetrahydropteroylpolyglutamate. The enzyme also catalyzes the formation of (6S)-5-formyltetrahydropteroylpolyglutamate from a compound in equilibrium with (6R)-5,10-methenyltetrahydropteroylpolyglutamate believed to be (6R,11R)-5,10-hydroxymethylenetetrahydropteroylpolyglutamate , a putative intermediate in the nonenzymatic hydrolysis of 5,10-methenyltetrahydropteroylglutamate to 5-formyltetrahydropteroylglutamate [Stover, P., & Schirch, V. (1992) Biochemistry (preceding paper in this issue)]. The enzymatic mechanism for the formation of (6S)-5-formyltetrahydropteroylpolyglutamate from these substrates and the role of glycine in the reaction was addressed. Evidence suggests that (6R,11R)-5,10-hydroxymethylenetetrahydropteroyltetraglutamate++ + is a catalytically competent intermediate in the enzyme-catalyzed hydrolysis of (6R)-5,10-methenyltetrahydropteroyltetraglutamate. The enzyme displays a high Km of 40 microM for (6R)-5,10-methenyltetrahydropteroyltetraglutamate, while the Km for (6R,11R)-5,10-hydroxymethylenetetrahydropteroyltetraglutamate++ + is below 0.5 microM. The kcat values for both reactions are identical and equal to the rate of formation of an enzyme ternary complex absorbing at 502 nm which is formed from glycine and (6S)-5-formyltetrahydropteroylpolyglutamate. The hydrolysis reaction proceeds with exchange of the C11 formyl proton of (6R)-5,10-methenyltetrahydropteroyltetraglutamate, suggesting that the enzyme-catalyzed reaction occurs by the same C11 carbanion inversion mechanism as the nonenzymatic reaction. Isotope exchange experiments using [2-3H]glycine and differential scanning calorimetry data suggest both a catalytic and a conformational role for glycine in the enzymatic reaction. The results are discussed in terms of the similarity in mechanisms of the SHMT-catalyzed retroaldol cleavage of serine and hydrolysis of (6R)-5,10-methenyltetrahydropteroylpolyglutamates.     

Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.     

Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex

The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S nuclear ribosomal DNA sequence and the intervening 5.8S region were sequenced from three individuals in each of eight taxa of the Mimulus guttatus species complex. Three discrete variants, or "types," of ITS sequences were found, among which 30%-40% of sites differed, compared with 1%-2% within types. Dot plots indicate that these types were not related by conspicuous rearrangements or inversions. More than one ITS type was often found in the same taxon, and two of three ITS types span species boundaries, indicating their presence prior to speciation. These ITS sequences showed essentially no positional homology with the nearest sequenced relative, tomato. In contrast, the 5.8S region was relatively unvaried, with 8 of 162 sites varied in the sample among all eight taxa. The phylogeny inferred by the most common ITS sequence type, rooted by the two other ITS types, agreed with isozymes in showing the distinctness of M. nudatus, M. laciniatus, and M. tilingii from the other five taxa.      

Haploinsufficiency of cytosolic serine hydroxymethyltransferase in the Smith-Magenis syndrome.

Folate-dependent one-carbon metabolism is critical for the synthesis of numerous cellular constituents required for cell growth, and serine hydroxymethyltransferase (SHMT) is central to this process. Our studies reveal that the gene for cytosolic SHMT (cSHMT) maps to the critical interval for Smith-Magenis syndrome (SMS) on chromosome 17p11.2. The basic organization of the cSHMT locus on chromosome 17 was determined and was found to be deleted in all 26 SMS patients examined by PCR, FISH, and/or Southern analysis. Furthermore, with respect to haploinsufficiency, cSHMT enzyme activity in patient lymphoblasts was determined to be approximately 50% that of unaffected parent lymphoblasts. Serine, glycine, and folate levels were also assessed in three SMS patients and were found to be within normal ranges. The possible effects of cSHMT hemizygosity on the SMS phenotype are discussed.     

Biological activities of melanotropic peptide fatty acid conjugates.

Four fatty acids (FA, palmitic, myristic, decanoic, hexanoic) were individually conjugated to the N-terminus of the alpha-MSH fragment analog, H-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10-NH2. This resulted in enhanced potency of the conjugates (compared to the unconjugated melanotropin analog) as determined in the lizard skin bioassay and in the mouse melanoma cell tyrosinase bioassay. The shorter conjugates of hexanoic and decanoic acid were at least equipotent to alpha-MSH in the lizard skin bioassay, whereas the longer myristoyl and palmitoyl analogs were 100 times less active. The myristoyl and palmitoyl conjugates exhibited a "creeping" potency in the lizard skin bioassay-that is, potency of the peptides increased with time in contact with the skins. These observations may be related to the more lipid nature of these FA-conjugates. In the tyrosinase assay, the conjugates were 10-100 times more active than alpha-MSH or the unconjugated analog. Each of the FA-melanotropic peptide conjugates exhibited prolonged (residual) melanotropic activity in both the lizard skin and melanoma cell bioassays. In other words, after removal of the melanotropin conjugates from contact with the skins or cells, responses were still manifested for hours or days thereafter. As little as 1 hr of contact with melanoma cells resulted in enhanced enzyme activity as measured 48 hr later. Since the conjugates, but not H-[Asp5, D-Phe7, Lys10]alpha-MSH5-10-NH2, exhibited prolonged activity, the conversion of reversible agonists to irreversible agonists was demonstrated.     

中国小菇属十个新记录种

报道了小菇科小菇属真菌10个中国新记录种,香菌组：橙盖小菇Mycena aurantiidisca、黄白小菇Mycena flavoalba、粉黄小菇Mycena floridula;棘刺组：异刺小菇Mycena heteracantha;纤柄组：碱味小菇Mycena amygdalina;脆足组：粉被小菇Mycena zephirus;冬生组：绣线菊小菇Mycena speirea、冬生小菇Mycena hiemalis;小菇组：绒柄小菇Mycena flos-nivium,分别来自吉林等11个省份、自治区。提供了每个物种的形态描述和线条图,以及与相近种的讨论。共计90条自测及下载ITS序列,在采用贝叶斯法和最大似然法构建的小菇属系统发育树中,新记录种均得到分子数据支持。凭证标本存放于吉林农业大学菌物标本馆（HMJAU）。     

Age‐related deterioration of motor function in male and female 5xFAD mice from 3 to 16 months of age

Alzheimer's disease (AD) is a neurodegenerative disorder that leads to age‐related cognitive and sensori‐motor dysfunction. There is an increased understanding that motor dysfunction contributes to overall AD severity, and a need to ameliorate these impairments. The 5xFAD mouse develops the neuropathology, cognitive and motor impairments observed in AD, and thus may be a valuable animal model to study motor deficits in AD. Therefore, we assessed age‐related changes in motor ability of male and female 5xFAD mice from 3 to 16 months of age, using a battery of behavioral tests. At 9‐10 months, 5xFAD mice showed reduced body weight, reduced rearing in the open‐field and impaired performance on the rotarod compared to wild‐type controls. At 12‐13 months, 5xFAD mice showed reduced locomotor activity on the open‐field, and impaired balance on the balance beam. At 15‐16 months, impairments were also seen in grip strength. Although sex differences were observed at specific ages, the development of motor dysfunction was similar in male and female mice. Given the 5xFAD mouse is commonly on a C57BL/6 × SJL hybrid background, a subset of mice may be homozygous recessive for the Dysf ^im mutant allele, which leads to muscular weakness in SJL mice and may exacerbate motor dysfunction. We found small effects of Dysf ^im on motor function, suggesting that Dysf ^im contributes little to motor dysfunction in 5xFAD mice. We conclude that the 5xFAD mouse may be a useful model to study mechanisms that produce motor dysfunction in AD, and to assess the efficacy of therapeutics on ameliorating motor impairment.