ENZYME ACTIVITIES DURING THE ASEXUAL CYCLE OF NEUROSPORA CRASSA

Abstract

Three enzymes, (a) nicotinamide adenine diphosphate-dependent glutamic dehydrogenase (NAD enzyme), (b) nictoinamide adenine triphosphate-dependent glutamic dehydrogenase (NADP enzyme), and (c) nicotinamide-adenine dinucleotidase (NADase), were measured in separate extracts of Neurospora crassa grown in Vogel's medium N and medium N + glutamate. Specific activities and total units per culture of each enzyme were determined at nine separate intervals phased throughout the asexual cycle. The separate dehydrogenases were lowest in the conidia, increased slowly during germination, and increased rapidly during logarithmic mycelial growth. The amounts of these enzymes present during germination were small when compared with those found later during the production of the conidiophores. The NAD enzyme may be necessary for pregermination synthesis. The NADPenzyme synthesis was associated with the appearance of the germ tube. Although higher levels of the dehydrogenases in the conidiophores resulted in more enzyme being found in the differentiated conidia, the rate of germination was uneffected. The greatest activity for the NADase enzyme was associated with the conidia, early phases of germination, and later production of new conidia. NADase decreased significantly with the onset of logarithmic growth, remained low during the differentiation of conidiophores, and increased considerably as the conidiophores aged.

Enzyme activities during the asexual cycle of Neurospora crassa. III. Nicotinamide adenosine diphosphate glycohydrolase

“…as well as the s~ecific activity for NAD;~~, were 'determined d u h g morphologlThis research was jointly sponsored by the U.S. ical development throughout the-asexual cycle Public Health Service (grant GM07607 to the University (8,9). was dependent on the age of the culture.…”

Carbon Source Regulation of Nicotinamide Adenine Dinucleotide (Phosphate) Glycohydrolase in Neurospora crassa: Induction and Repression of Enzyme Synthesis

“…NAD(P)ase production was induced by the presence of protein as the sole carbon source in the culture medium, and more efficient carbon sources such as sucrose and glucose were repressors of NAD(P)ase production ( Table 1). It is interesting that NAD(P)ase was induced, in the presence of protein, even in shaken cultures, in which NAD(P)ase synthesis has previously been shown to be inhibited (Stine, 1968;Nelson et al, 1976).…”

“…We showed (Jorge & Terenzi, 1980) that the cyclic AMP-deficient, hyperconidiating mutant, strain cr-1 (crisp-1) continuously produces and secretes NAD(P)ase, and that the enzyme level decreases when the mutant is cultivated in the presence of cyclic AMP, which also corrects the morphology defect. However, conidiation does not seem to be a prerequisite for the production of NAD(P)ase, since the aconidial strain Jluffv makes large amounts of the enzyme (Stine, 1968). On the other hand, the absence of NAD(P)ase did not affect the growth of aerial hyphae, conidiation or conidial germination in five defective mutant strains (nada) studied (Nelson et al, 1975).…”

“…Following this discovery Zalokar & Cochrane (1 956) found that NAD(P)ase activity increased sharply during conidiation. Stine (1968) showed that NAD(P)ase activity appeared together with the formation of aerial hyphae, accumulating in conidia and decreasing very fast as the mature conidia germinated. Combkpine & Turian (1970) concluded that NAD(P)ase was important to conidiogenesis.…”

Distribution of Wall-bound Invertase during the Asexual Life-cycle of Neurospora crassa

“…Therefore, most of the invertase activity must be free within the periplasmic space and/or associated with the outside of the plasma membrane. The transition of Neurospora to a highly active metabolic state during germination of conidia and subsequent logarithmic growth is often accompanied by increased enzymatic activities in biosynthetic pathways (Stine, 1968), in respiratory activities (Zalokar, 1959 ;Weiss, 1963), and in various hydrolytic reactions (Hill & Sussman, 1964;Scott & Metzenberg, 1970). The increase in specific activity of total cellular invertase as well as wall-bound invertase observed here probably reflects the active synthesis and secretion of this enzyme during the initial stages of the Neurospora life-cycle.…”