Microorganisms colonizing allochthonous detritus (live oak leaves) incubated in a north Florida estuary show metabolic activity that can be assayed reproducibly by the incorporation of [32P]H3PO4 and [1‐14C] sodium acetate into the lipids in a 2‐h period without introducing subculture bias. Relatively uncolonized live oak leaves show only about 1% of the biosynthetic capacity of leaves incubated in the estuary for 1 week. Lipid synthesis is proportional to time for at least 2 h and also to detrital mass. Random sampling from pooled portions of many leaves greatly reduces the variance of activities from individual leaves. Rates of phospholipid synthesis paralleled the total extractable ATP and the alkaline phosphatase activity during a 6‐week incubation of live oak leaves in Apalachicola Bay. Rates of 14C incorporation into lipids paralleled the respiratory and the α‐d‐mannosidase

Thirty previously unmapped markers have been located; 13 are at newly designated loci. Numerous sequences for previously mapped genes have also been determined. A revised map of linkage group I is presented. The order from conventional mapping has been confirmed by testing recessive markers in IL for coverage by duplications. Assignment of new mutants to linkage groups is greatly facilitated by using gene-tagged multiple translocation strains for linkage detection; these "alcoy" tester strains and procedures for using them are described. Recent mapping data of other workers are compiled. Distal markers are now known for all but one of the 14 chromosome arms, but extensive map segments are still devoid of markers.

Earlier studies have shown that the activity of the estuarine detrital microflora measured by various enzyme activities, muramic acid and adenosine 5'triphosphate (ATP) content, heterotrophic potentials, and respiratory activities correlates with the incorporation of 14C and 32p into the microbial lipids. In this study, these lipids were reproducibly fractionated into neutral lipid, glycolipid, and phospholipid classes. Distinct differences between the active microflora of oak leaves, sweet gum leaves, and pine needles were evidenced both in the rate of lipid synthesis and in the proportions of neutral lipids, glycolipids, and phospholipids. Successional changes in the microflora of leaves incubated in a semitropical estuary, previously suggested by ATP-to-muramic acid ratios and scanning electron micrography, were reflected in changes in the proportions of 14C in major lipid classes when analyzed from the same type of detritus. Short incubation times with 14C gave lipid compositions rich in phospholipids that are typical for the faster-growing bacterial populations; longer incubation with I4C gave lipid compositions richer in neutral and glycolipids, more characteristic of slower-growing eukaryotes or morphologically more complex prokaryotes. The metabolism of the lipids of the estuarine detrital microflora was examined by a pulse-chase experiment with 14C. Glycolipids lost 14C at a rate equal to the loss of '4C of the slow component of muramic acid. Individual phospholipids lost 14C from their backbone glycerol esters at different rates.

D e p n~n~~e n t of Biological Scie~~ces, Stnzford U~~h e~s i t y , Stmaford, C r r l i f o~~~i a Inversion b1(ILR)N1bll'i6 has onc brcak point at thc cxtrcmc right cnd of linlcage group I and thc other distal to mating typc in the left arm. In crosscs of Inversion x Normal thc products of single crossing ovcr within the invcrsion arc complcn~cntary duplication-deficicnc\i classcs. Onc crossover product is viable, \vith a large scgnlcnt of IL duplicatcd and thc dispcnsablc right tip presumably tlcficicnt. This class has low fertility and distinctive morphology. T h e complementary product has a large dcficicncy which results in a pair of white, inviable ascosporcs. Singlc cxchangcs within the hetcrozygous inversion thus producc asci with 6 Black: 2 Whitc spores; four-strand doublc cxchangcs produce 4 B:-l W ; and non-cxcha~~gcs producc asci wit11 8 B:O W. Approximate mapping of brcalc points Xvas accomplished by three-point crosscs. Prccisc placcmcnt of thc lcft brcalc point bctwccn s e~-3 and zn1 (11701t), just left of mating type, is bascd on col-cmgc of marltcrs by thc hctcroiygous duplication. S o crossox-cr has bccn obtained between mating typc and the brcalc point, dcspitc cxtcnsivc efforts. hL(lLR)N~\4176 differs from thc invcrsiocl I?I(ILIZ) H42i0 dcscril)cd by Ncwmcycr and Taylor (1967) in oilc main rcspcct: thc mating typc locus is inclildcd in the invcrtcd scgmcnt of Ni\/I176. Conscqi~cntly, mhcn duplications arc gcncratcd, thc progeny arc unisexual and do not havc thc unstable inhibited phenotype characteristic of H4250 duplication progeny, which arc hctcrozygous for thc mating typc allclcs A and n. Three othcr invcrsions which originated indcpcndcntly of 111(ILR)N1MI76 rcscmblc it closcl!. and havc similar or identical brcalc points.

URING a study of the arginine-1 locus in Neurospora crmsa, one mutant strain (H4250) was found to produce, on crossing to wild type, an unusual class of progeny. These progeny initially show very slow "inhibited" growth with a characteristic spidery morphology, and are darkly pigmented on complete medium; they are therefore called Dark Agars. After several days, they escape from the inhibition and grow like wild type; many of the resulting cultures behave as if both mating-type alleles are present. The present study shows that the Dark Agars are viable duplications produced by crossing over in a pericentric inversion. The initial inhibition appears to be due to heterozygosity for the mating-type locus, which is included in the duplication; the cultures formed after escape from inhibition are mixtures of somatic derivatives that are homozygous or hemizygous for mating type. Somatic segregation for other markers in the duplicated region is also found.The H4250 inversion provides favorable material for studying somatic segregation, because the duplilcation covers 50 map units in a well marked region, and because there is strong selection for the products of somatic segregation, which can be recovered and purified by plating.