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Polyphenol oxidases are known to be produced by a range of ectomycorrhizal (ECM) and ericoid mycorrhizal fungi. These enzymes include laccase (EC 1.10.3.2), catechol oxidase (EC 1.10.3.1) and tyrosinase (EC 1.14.18.1), between which there exists considerable overlap in substrate affinities. In this review we consider the nature and function of these enzymes, along with the difficulties associated with assigning precise enzymatic descriptions. The evidence for production of laccase and other polyphenol oxidases by ECM and ericoid mycorrhizal fungi is critically assessed and their potential significance to the mycorrhizal symbioses discussed.

Summary • Genes for ligninolytic enzymes, normally associated with white-rot fungi, are shown to be widespread in a broad taxonomic range of ectomycorrhizal (ECM) fungi. • ECM fungi were screened for lignin peroxidase (LiP) and manganese peroxidase (MnP) genes by PCR using primers specific for known isozymes in the white-rot fungus Phanerochaete chrysosporium, with DNA sequencing used to confirm the identity of the amplified fragments. • Genes for LiPs were detected in ECM fungi representing the orders Agaricales, Aphyllophorales, Boletales, Cantharellales, Hymenochaetales, Sclerodermatales, Stereales and Thelephorales. MnP genes were detected in only Cortinarius rotundisporus and three ECM Stereales taxa. • The presence of genes for decomposer activities supports putative evolutionary relationships between ECM and saprotrophic fungi. Expression of the lignolytic genes may facilitate ECM fungal access to nutrients associated with dead plant material in soil and potentially a supplementary carbon supply. Strict functional boundaries between ECM and decomposer fungi may be less clear-cut than previously thought.

beta-(25-35) is a synthetic derivative of beta-amyloid, the peptide that is believed to cause Alzheimer's disease. As it is highly toxic and forms fibrillar aggregates typical of beta-amyloid, it is suitable as a model for testing inhibitors of aggregation and toxicity. We demonstrate that N-methylated derivatives of beta-(25-35), which in isolation are soluble and non-toxic, can prevent the aggregation and inhibit the resulting toxicity of the wild type peptide. N-Methylation can block hydrogen bonding on the outer edge of the assembling amyloid. The peptides are assayed by Congo red and thioflavin T binding, electron microscopy, and a 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) toxicity assay on PC12 cells. One peptide (Gly(25) N-methylated) has properties similar to the wild type, whereas five have varying effects on prefolded fibrils and fibril assembly. In particular, beta-(25-35) with Gly(33) N-methylated is able to completely prevent fibril assembly and to reduce the toxicity of prefolded amyloid. With Leu(34) N-methylated, the fibril morphology is altered and the toxicity reduced. We suggest that the use of N-methylated derivatives of amyloidogenic peptides and proteins could provide a general solution to the problem of amyloid deposition and toxicity.

Several reports attest to the apparent ability of some ectomycorrhizal (ECM) and ericoid (ERM) mycorrhizal fungi to produce peroxidase enzyme activities during growth in axenic culture. In critically reviewing these data, we highlight that apparent peroxidase activities have been observed during growth in media containing 60–70 μM Fe. ECM and ERM fungi are known to produce H2O2 via carbohydrate oxidase activity and conditions in common culture media are favourable to the production of hydroxyl radicals, superoxide radicals and ferryl ions via the Fenton reaction. Free radicals so produced can mediate oxidation of substrates commonly used in presumptive peroxidase assays, leading to false-positive results. We argue that there is currently no evidence to support production of peroxidase activity by ECM or ERM fungi, but highlight circumstances in which peroxidase expression might be observed in future work.

SUMMARY Isolates of the ericoid mycorrhizal fungus Hymenoscyphus ericae (Read) Korf et Kernan, and the ectomycorrhizal fungi Suillus variegatus (Swartz ex Fr.) and Pisolithus tinctorius (Pers.) Coker & Couch, along with a Cortinarius sp. and the white rot Phanerochaete chrysosporium Burdsall were examined for the ability to oxidize carbohydrates to their corresponding lactones and to excrete the H202 produced thereby. All except Phanerochaete chrysosporium were found to express cellobiose oxidase (cellobiose dehydrogenase, EC 1. 1. 19.88) and glucose oxidase (/-Dglucose: oxygen 1 -oxidoreductase, EC 1 . 1 . 3.4) when grown on cellobiose and glucose respectively. Production of extracellular H202 was visualized during growth on both substrates using ABTS as the chromogen. According to the Fenton reaction, H202 will react with hydrated or chelated Fe(II) in the environment to produce hydroxyl (Fenton) radicals, HO'. Mycelial extracts from each of the mycorrhizal fungi produced HO in the presence of cellobiose and Fe(II), presumably mediated by H202 produced by cellobiose oxidase activity in the extracts. Conditions favourable to HO production were shown to exist in Modified Melin-Norkrans medium, and the data discussed in relation to previously observed lignin degradation by mycorrhizal fungi.

Hymenoscyphus ericae (Read) Korf & Kernan is known to form mycorrhizas with a number of host plants in the Ericaceae. The fungus produces a range of extracellular enzyme activities which have the potential to mediate utilisation of organic sources of nitrogen and phosphorus in soil. H. ericae has recently been shown also to produce enzyme activities that may allow the fungus to decompose components of the plant cell wall, facilitating access to mineral nutrients sequestered within the walls of moribund plant cells. In this review we assess the evidence for production of cellulolytic, hemicellulolytic, pectinolytic and ligninolytic activities by H. ericae and discuss their likely relevance to nutrient cycling processes.

The cellular production by resident articular cells and infiltrating inflammatory cells of the gelatinase matrix metalloproteinases (MMP) was investigated by tissue culture methods and analysis of cell supernatants by gelatin zymography. Peripheral blood neutrophils in short term culture produced MMP-9, as did peripheral blood monocytes in culture. Isolated articular chondrocytes in monolayer culture produced both MMP-2 and MMP-9, although articular cartilage maintained as explant culture produced MMP-2 alone. Synovial fibroblasts grown in monolayer culture produced MMP-2 alone, although synovial membrane in explant culture produced both MMP-2 and the active form of MMP-2. Lysis of blood polymorph neutrophils produced large quantities of MMP-9, but lysis of blood monocytes, synovial fibroblasts and articular chondrocytes produced little enzyme indicating that, unlike the other cell types, polymorph neutrophils store MMPs intracellularly. Equine MMP-2 was purified from synovial fibroblast cell culture supernatant, and equine MMP-9 from polymorph neutrophil cell culture supernatant, by gelatin-sepharose affinity chromatography. The 2 enzymes were identified from their molecular weights and by their respective N-terminal amino acid sequences which showed homology with the enzymes from other species. The demonstration that invasive cells and resident articular cells can produce enzymes which are capable of digestion of certain component molecules of the articular cartilage matrix, shows that therapeutic targeting of these enzymes could be a valid proposition in the prevention of cartilage destruction in osteoarthritis.

SUMMARY A fl-1,4-endoxylanase from the ericoid mycorrhizal fungus H. ericae has been purified to electrophoretic homogeneity using isoelectric focusing, ion exchange and gel permeation chromatography. The enzyme has an isoelectric point of 4-85-5-20 and a molecular weight of 58 4 kDa. The apparent S0.5 of the enzyme for soluble birchwood glucuronoxylan is 3-75 mg ml-1 and the VTax 468-0 nkatal mg-1 protein. The pH optimum for activity is 4 5 and that for stability is 3 5-4 0; these values are discussed in the context of the pH of the mor humus. The role of wall-degrading activities in the establishment of the ericoid mycorrhizal symbiosis is considered.

Application of the thermoluminescence (TL), fine-grain (4–11 μm) dating method to modern coastal deposits and to tectonically displaced sediments near the Mendocino Triple Junction in northern coastal California demonstrates the suitability and limitations of dune sand, buried soil, estuarine mud, and beach deposits for TL dating. TL measurements on modern estuarine mud, modern beach sediments, and radiocarbon-dated dune sand and soils show that these deposits are suitably zeroed for TL dating under some conditions. A weighted mean TL age of 16.4 ± 1.3 ka was obtained for four samples (two from a buried soil and two from the straddling terrace dune sand), in close agreement with a radiocarbon age of 16.84 ± 0.06 ka B.P. on charcoal from this paleosol. Application to older sediments and soil profiles of similar origin may therefore provide useful geological ages. Deposits associated with deformed marine terraces yielded TL ages of 176 ± 33 ka for a shallow marine mud at the Mad River site and 119 ± 31 ka for nearshore deposits at the Southport Landing site. These age estimates are consistent with the stratigraphic positions of the TL samples relative to deposits having previously inferred ages based upon soil profile correlations to local age assignments, which are in turn based upon uplift rates relating to eustatic sea level stands. These single TL age results suggest that more detailed TL dating applications in this region, and in similar geological settings, could provide accurate estimates of geologic ages and rates of deformation. However, the polymineralic fine grains from two other nearshore deposits (at the Table Bluff and Centerville Beach sites) yielded ambiguous plateau plots and thus can not be considered datable without additional TL experiments. This difficulty may be due to a high quartz/feldspar ratio in sediments from this area.

summary Glycerol, mannitol and proline, compatible solutes produced by fungi in response to salt or water stress, can be involved in futile or substrate cycles. It is argued, on the basis of chemostat cultures with both bacteria and fungi, that substrate cycles which dissipate energy are necessary processes when fungi are subjected to osmotic or water stress. Whether or not the three compounds are also involved in overflow metabolism remains to be established. It is argued that substrate cycles may have more general importance when a fungus is growing under types of stress other than that caused by high concentrations of salt or low availability of water. The arguments put forward strengthen the case for considering the three compounds as part of a general class of physiological buffering agents. A modified version of the mannitol cycle is proposed.

β(25–35) is a fragment of β-amyloid that retains its wild-type properties. N-methylated derivatives of β(25–35) can block hydrogen bonding on the outer edge of the assembling amyloid, so preventing the aggregation and inhibiting the toxicity of the wild-type peptide. The effects are assayed by Congo Red and thioflavin T binding, electron microscopy and an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] toxicity assay. N-methyl-Gly-25 has similar properties to the wild-type, while five other methylation sites have varying effects on prefolded fibrils and fibril assembly. In particular, N-methyl-Gly-33 is able to completely prevent fibril assembly and reduces the toxicity of prefolded amyloid. With N-methyl-Leu-34 the fibril morphology is altered and toxicity reduced. A preliminary study of β(25–35) structure in aqueous solution was made by small-angle neutron scattering (SANS). The protofibrillar aggregates are best described as a disc of radius 140 å and height 53 å (1 å = 0.1 nm), though the possibility of polydisperse aggregates cannot be ruled out. No aggregates form in the presence of N-methyl-Gly-33. We suggest that the use of N-methylated derivatives of amyloidogenic peptides and proteins could provide a general solution to the problem of amyloid deposition and toxicity and that SANS is an important technique for the direct observation of protofibril formation and destruction in solution.

beta-(25-35) is a synthetic derivative of beta-amyloid, the peptide that is believed to cause Alzheimer's disease. As it is highly toxic and forms fibrillar aggregates typical of beta-amyloid, it is suitable as a model for testing inhibitors of aggregation and toxicity. We demonstrate that N-methylated derivatives of beta-(25-35), which in isolation are soluble and non-toxic, can prevent the aggregation and inhibit the resulting toxicity of the wild type peptide. N-Methylation can block hydrogen bonding on the outer edge of the assembling amyloid. The peptides are assayed by Congo red and thioflavin T binding, electron microscopy, and a 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) toxicity assay on PC12 cells. One peptide (Gly(25) N-methylated) has properties similar to the wild type, whereas five have varying effects on prefolded fibrils and fibril assembly. In particular, beta-(25-35) with Gly(33) N-methylated is able to completely prevent fibril assembly and to reduce the toxicity of prefolded amyloid. With Leu(34) N-methylated, the fibril morphology is altered and the toxicity reduced. We suggest that the use of N-methylated derivatives of amyloidogenic peptides and proteins could provide a general solution to the problem of amyloid deposition and toxicity.

Summary A canine gelatinase, with an apparent molecular mass of 62kDa in non-reducing zymography, is produced by fibroblasts, chondrocytes and a myelomonocytic cell line. The enzyme has similar characteristics to human matrix metalloproteinase (MMP) 2 and cross-reacts in Western blotting analysis with a sheep polyclonal antiserum raised against human MMP-2. The 62kDa canine protein was purified from cell culture media, and the N-terminal amino acid sequence determined following blotting on to a polyvinylidene difluoride (PVDF) membrane. The sequence was 87% identical to that published for human MMP-2. We therefore consider this enzyme to be canine MMP-2.

There is increasing evidence that (at least) some ectomycorrhizal fungi produce enzymes capable of degrading components of the plant cell wall (reviewed by Cairney and Burke 1994). The functional significance of such enzymes is not yet clear, but it has been suggested that their production in parts of extramatrical mycelial systems might facilitate degradation of moribund plant wall material in soil. This, in turn, may permit hyphal access to mineral nutrients sequestered therein and/or provide a source of carbon to the fungi supplementary to that obtained from the host plant (Cairney and Burke 1994; Durall et al. 1994). Despite their potential significance to the symbiosis, only a limited number of isolates of a small number of ectomycorrhizal fungal species have been screened for enzyme production under a limited range of conditions. To fully appreciate the roles of plant wall-degrading enzymes in the symbiosis there is a clear need for more comprehensive screening.

Following a retrospective review of tuberculosis cases reported from Ottawa County, Oklahoma, from 1969 through 1973, a selective tuberculosis screening project was implemented. Screening of a "target group" of the population, 519 former miners, greater than or equal to 50 years of age, resulted in the discovery of abnormal chest X-rays in 182; (103 with silicosis, 36 with silicotuberculosis, 12 with inactive tuberculosis, and 31 with other abnormalities). Eighty-five of these persons had positive tuberculin skin tests. Preventive therapy was recommended for 50, and 36 completed the prescribed course of treatment. Eight new bacteriologically confirmed cases of tuberculosis were found and treated. A large number of persons (1,904) residing in the same area who were not part of the target group were also screened for tuberculosis. This group contained a large number of positive tuberculin reactors but very few were candidates for isoniazid preventive therapy. Thirteen persons in this group had abnormal chest X-rays consistent with inactive tuberculosis but 12 had been identified and given preventive therapy before the project began. These data suggest that selective approaches to screening for tuberculosis in a community which are based on an in-depth retrospective review of the tuberculosis case register can be highly successful.

Four valleys, recently studied by other workers, were examined along the eastern Sierra Nevada to refine relative-dating techniques. A variety of weathering parameters and soil properties fail to delineate more than two major post-Sherwin Pleistocene glaciations. We correlate these two glaciations with the Tahoe and Tioga Glaciations. Type Mono Basin Till, usually considered to be pre-Tahoe, exhibits the following weathering similarities with Tahoe Till, if both are under sagebrush: (1) grusification of subsurface granitic boulders; (2) degree of pitting, mineral relief, and rind development on surface granitic boulders; and (3) very slight clay increase in the B horizon. Type Casa Diablo Till also has weathering characteristics similar to Tahoe Till, except a slightly more developed Bt horizon is present. Hence, dates on basalt of 0.126 ± 0.025 and 0.062 ± 0.013 my Casa Diablo Till also has weathering characteristics similar to Tahoe Till, except a slightly more developed Bt horizon is present. Hence, dates on basalt of 0.126 ± 0.025 and 0.062 ± 0.013 my (Bailey et al. 1976), which bracket type Casa Diablo, may provide age control on the Tahoe glaciation. In addition, we are unable to demonstrate that the Tenaya is a separate glaciation. In three of the four valleys studied our weathering data for Tenaya Till are equivalent with those for Tioga Till, but with those for Tahoe Till in the fourth valley. We were not satisfied with our ability to differentiate the Casa Diablo, Mono Basin, and Tenaya as separate glaciations even though data were collected in the type areas for two of these deposits. Reasons for suggesting a change back to a two-fold Tahoe-Tioga glacial sequence, rather than the present five-fold sequence, are that we have measured a greater number of parameters than has been done previously, soils were submitted to detailed laboratory analyses, and surface weathering features were studied under consistent present vegetation cover to avoid possible problems induced by ancient forest fires. Nevertheless our relative-dating scheme does not rule out the possibility of a more detailed glacial sequence.

Soils and subsurface rock-weathering features developed in Sherwin and pre-Sherwin tills were studied in the Sherwin Till type locality and in Bridgeport Basin to determine those characteristics useful (1) in distinguishing these deposits from those of Tahoe age, and (2) in subdividing and correlating pre-Tahoe deposits along the eastern side of the Sierra Nevada. To aid in these two goals, laboratory data were obtained on pH, particle-size distribution, two fractions each of free Fe and free Al, and two P fractions, but only data on particle size and one Fe fraction proved to be useful. If stable surface sites are compared, soils formed in Sherwin Till have much better developed Bt horizons, as indicated by clay content, clay films, and redness, than those in Tahoe Till. Grusification of granitic clasts is about the same in both Tahoe and pre-Tahoe tills, but metamorphic and volcanic rocks are much more weathered in pre-Tahoe deposits. The best developed soils thought to be of Sherwin age are those in Bridgeport Basin, but the correlation with the type locality of the Sherwin Till is uncertain. Soils formed in type Sherwin Till are less well developed than those formed in Bridgeport Basin deposits, probably either because the former soils are younger, having formed on an exhumed surface following the removal of the overlying Bishop Tuff, or because of climatic and lithologic differences. Data on a weakly developed soil in the uppermost part of the type Sherwin Till, buried by the Bishop Tuff, help to confirm Sharp's (1968) estimate of the date of the Sherwin Glaciation at about 0.75 m.y. B.P. Type Sherwin Till buries a soil formed in still older till in Rock Creek gorge, and a minimum time for the formation of that soil is about 100,000 yr.

The most useful and objective classification for alpine glacial deposits, as well as for many other Quaternary deposits, appears to be one based on parameters which vary with age as a result of postdepositional modifications. In areas and units for which radiometrically datable materials are rare, age information is gained primarily from these postdepositional modifications by what are here called relative-dating (RD) methods. In order for alpine glacial deposits to be subdivided and formally named, sufficient field data for consistent recognition and mapping need to be collected. These data include measurements of age-dependent parameters such as soil properties, rock-weathering characteristics, and landform changes. Subdivision and naming of glacial deposits should be no more detailed than the resolution of the RD methods, which generally decreases with time. Only when deposits have been objectively characterized by these relative-dating methods can correlations with deposits in other areas or with other types of records be substantiated.

Soil catena development is traced through time by comparing soil catenas on Tioga, Tahoe, and Mono Basin moraines in two eastern Sierra Nevada, California, valleys, Green Creek and Walker Creek. Shortly after moraine deposition, slope adjustment takes place and a sandy colluvial wedge is deposited at the footslope. Since the Tioga glaciation of about 20,000 yr ago, A/Bw/Cox soil profiles have formed along the catena, and values of the profile development index, and weighted mean and accumulation index of laboratory properties are similar at most sites. Data for the Tahoe and Mono Basin catenas are used to track catena soil development for the preceding approximately 100,000 yr. In the most impressive case (Green Creek), Bt horizons have formed at most sites along the catena and profile development, as judged from both field data and laboratory data on pedogenic clay and iron, is best at footslope sites. However, in the stratigraphically important moraine sequence of Walker Creek, there are little or only subtle differences in total catena development values with time. Comparison with other recent studies indicates that these results are representative of a larger area in the western United States. When using soils for age differentiation of moraines, it is strongly suggested that footslope soils should be included in the analysis.