Incorporation of 18O2 and absence of stereospecificity in primary product formation during fungal metabolism of a lignin model compound

The metabolism of a lignin substructure model compound, 1,2-bis(3-methoxy-4-ethoxyphenyl)propane-1,3-diol (Ia) in ligninolytic cultures of Phanerochaete chrysosporium was studied to help elucidate the biochemical mechanism of lignin degradation. The primary reaction was cleavage of the model compound between C₁ and C₂ of the propane moiety to produce 1-(3-methoxy-4-ethoxyphenyl)ethane-1,2-diol and a C₆-C₁ product (probably 3-methoxy-4-ethoxybenzaldehyde). Other identified products arose secondarily; all were further metabolized. Even though the model compound was a mixture of four stereoisomers, no stereoselectivity was observed in its metabolism. In cultures under ¹⁸O₂, the initial cleavage produced the diol product with ≈70% enrichment by ¹⁸O in the benzyl alcohol group. The diol was a mixture of the two possible enantiomers, and the O₂-derived hydroxyl was incorporated at the asymmetric (benzyl) carbon. (Limited optical activity in the diol was traced to selective further metabolism of the D form.) These results show that the primary cleavage reaction lacked stereospecificity and was primarily oxygenative, implicating a nonspecific oxygenase or a nonenzymatic reaction involving activated oxygen. Preliminary experiments demonstrated no cell homogenate activity against Ia.     

Changes in brain muscarinic acetylcholine receptors and behavioral responses to atropine and apomorphine in chronic atropine-treated rats

Chronic blockade of cholinergic transmission with atropine resulted in a decrease in atropine-induced activity in the rats, whereas apomorphine - induced locomotion was enhanced. Maximal binding of ³H-quinuclidinyl benzilate (QNB), a muscarinic antagonist, to homogenate of cerebral cortex, striatum and hippocampus was significantly higher in chronic atropine-treated rats than in control animals. No difference was observed in K_D value of the specific ³H-QNB binding or in ID₅₀ value of oxotremorine in inhibiting ³H-QNB binding. No change in the specific binding of ³H-spiroperidol, a dopaminergic antagonist, was observed in those three regions of brains of chronic atropine-treated rats when it was compared with that of control animals. The role of brain muscarinic acetylcholine receptors in behavioral responses is discussed relating an effect of dopaminergic neurons on cholinergic activities.     

The inheritance mode of simian-type E,F, and GH blood groups in cynomolgus monkeys

The mode of inheritance of four different red cell antigens (E^cy, F^cy, G^cy, and H^cy), detected by alloimmune reagents prepared by us for the cynomolgus monkey, was studied. The results of the segregation analysis suggest that each antigen is inherited in an autosomal dominant manner. Both the random sample analysis and family study revealed that two of these red cell antigens (E^cy and F^cy) probably represent the products of two independent genes while the expression of the other two antigens (G^cy and H^cy is governed by two autosomal codominant alleles. Thus, three simian-type blood group systems could be demonstrated by the four newly developed alloimmune reagents. We use the following nomenclature for these blood groups: the E and F blood groups, each with two phenotypes, antigen positive (E and F) and antigen negative (e and f), and the GH blood group having three phenotypes (G, H, and GH).     

Luteinizing hormone receptors in ovaries of the cynomolgus monkey (Macaca fascicularis) during the menstrual cycle

Ovarian luteinizing hormone (LH) receptors were characterized using ovarian tissues from 17 cynomolgus monkeys at different phases of the menstrual cycle. Low binding affinity receptors for ¹²⁵I-LH were observed throughout the menstrual cycle. The binding affinity of these receptors for LH (< 12 × 10¹⁰ M^?1) was approximately the same as that of ovarian LH receptors previously reported in human and nonhuman primates. In addition, high-affinity receptors (17?85 × 10¹⁰ M^?1) were also detected at the mid-luteal phase, during which a large functional corpus luteum was present. Thus the high-affinity LH receptors appear with the formation of the corpus luteum and disappear with its regression. Almost no fluctuation of binding capacity was observed throughout the menstrual cycle (32?112 fmol/ mg of ovarian tissue). The high-affinity LH receptor was judged to be derived from the functional corpus luteum.     

Involvement of singlet oxygen in the fungal degradation of lignin

The possible involvement of singlet oxygen (¹O₂) in the degradation of lignin by $\text{Phanerochaete}\text{chrysosporium}$ was examined. Ligninolytic cultures and photochemically generated ¹O₂ gave the same oxidation products from the lignin substructure model compound 1,2-bis(3-methoxy-4-alkoxyphenyl)propan-1,3-diol. Fluorescence and near UV absorbance of the specific ¹O₂ trapping agent anthracene-9,10-bisethanesulfonic acid (AES) disappeared in ligninolytic cultures, indicating that ¹O₂ was produced. AES strongly inhibited oxidation of ¹⁴C-lignin, but not ¹⁴C-glucose, to ¹⁴CO₂ in cultures, and also strongly suppressed oxidation of the model compound. These results indicate the ¹O₂ plays an integral role in lignin biodegradation.     

Differentiation of mitochondrial DNA types inMacaca fascicularis

Restriction fragment length polymorphism in the mitochondrial DNA ofMacaca fascicularis from four geographical regions, Indonesia, the Philippines, Malaysia, and Indochina, was analyzed. In total, 21 types of mitochondrial DNA were detected using five restriction enzymes. These types were divided into two main groups based on phylogenetic analyses, one of which corresponded to the types of continental (Malaysia/Indochina) populations and the other to the types of a insular (Philippine) population. The types in the Indonesian population belonged to both groups. In the phylogenetic tree for the four populations, two clusters were constructed, one for the continental populations and the other for the insular ones.