Divergent fate of unsaturated and saturated ceramides and sphingomyelins in rat liver and cells in culture

The metabolism of sphingomyelins and ceramides with defined labeled fatty acids was compared after injection in vivo or incubation with cultured cells. The liver was the major site of uptake of sphingomyelins and ceramides with 18:2 or 16:0 fatty acids, but with both sphingolipids a higher recovery of radioactivity was found with 16:0 species. The distribution of radioactivity among liver lipids showed that 1.5 h after injection of 18:2 sphingomyelin, only 21% of the label was found as sphingomyelin, and this value was 37% in the case of 16:0 sphingomyelin. There was a very marked difference in the metabolism of 18:2 and 16:0 ceramides. After injection of 18:2 ceramide only 14% of the radioactivity was recovered as sphingomyelin, and this value was more than 50% with 16:0 ceramide. [14C]18:2 ceramide was converted also to glucoceramide and hydrolyzed more extensively than 16:0 ceramide. These observations were extended to sphingomyelins and ceramides with other fatty acids, using Hep-G2 cells in culture. Significantly more radioactivity was recovered as labeled sphingomyelin after incubation with 16:0, 18:0, 20:0 and 24:0 sphingomyelins than with 18:1 and 18:2 sphingomyelins, while more labeled phosphatidylcholine and phosphatidylethanolamine were found with the unsaturated sphingomyelins. In analogy to the findings in vivo, in the Hep-G2 cells more 16:0, 18:0 and 24:0 ceramides were converted to sphingomyelin than 18:1 or 18:2 ceramides. These differences were also seen with cultured macrophages, in which a more marked reutilization for sphingomyelin formation was found with the saturated ceramide series. The sphingomyelin liposomes were tested also for their capacity to mobilize cholesterol, and a rise in plasma unesterified cholesterol occurred after injection of 18:2 sphingomyelin. Marked enhancement of cholesterol efflux from cholesterol ester-loaded macrophages was also seen with 18:1 and 18:2, 20:0 sphingomyelin in the presence of delipidated high-density lipoprotein. The present results demonstrate that the metabolic fate of sphingolipids is related to their fatty acid composition. While ceramides with saturated fatty acids are predominantly reutilized for sphingomyelin formation, those with unsaturated fatty acids undergo probably more rapid hydrolysis with liberation of fatty acids and channeling into glycerolipids.     

War in Guatemala and Exile in Florida

Book reviewed in this article:
Unfinished Conquest: The Guatemalan Tragedy . Victor Perera. Berkeley: University of California Press, 1993. 382 pp. Maya in Exile: Guatemalans in Florida. Allan F. Burns. Philadelphia: Temple University Press, 1993. 208 pp.     

Ceramide and sphingomyelin species of fibroblasts and neurons in culture

The ceramide (Cer) and sphingomyelin (SM) species of cultured differentiated rat cerebellar granule cells and human fibroblasts were characterized by electrospray ionization-mass spectrometry. We identified 35 different species of Cer and 18 species of SM in human fibroblasts, and 35 different species of Cer and 9 species of SM were characterized in rat neurons. The main Cer species of rat cerebellar granule cells contained d18:1 sphingosine linked with palmitic, stearic, or nervonic fatty acid, and the two main SM species were d18:1,16:0 and d18:1,18:0. Both sphingolipids were enriched in detergent-resistant membranes (DRMs; or lipid rafts), and significant differences were found in the sphingolipid patterns of DRMs and of detergent-soluble fractions (DSF) from these cells. In human fibroblasts, the main Cer species were d18:1,16:0, d18:2,16:0, d18:1,24:0, d18:2,24:0, d18:1,24:1, and d18:2,24:1; the most represented species of SM were d18:1,16:0, d18:1,24:0, and d18:1,24:1. In these cells, SM was highly enriched in DRMs and Cer was mainly associated with DSF, and the species found in DRMs were markedly different from those found in DSF.     

Undergraduate teaching in gerodontology in Austria, Switzerland and Germany

Objective: To survey the present state of undergraduate teaching in the domain of gerodontology in Germany, Switzerland and Austria. Study participants: All universities of Austria (A), Germany (D) and Switzerland (CH). Protocol: A questionnaire on undergraduate teaching in gerodontology was mailed to all Deans (A: n = 3; CH: n = 4; D: n = 31) and all independent departments except paediatric dentistry and orthodontics (A: n = 11; CH: n = 15; D: n = 111). Results: The questionnaires were completed and returned by 29 Deans (A: n = 2; CH: n = 4; D: n = 23) and 102 departments (A: n = 7; CH: n = 8; D: n = 87). In Austria, gerodontology is a very small component of the dental curriculum and the Deans did not want this to be increased. Most German universities claimed to teach some aspects of gerodontology to undergraduate students and 87.4% of the Deans voted for separate lectures in gerodontology. In Switzerland, gerodontology seems well established. The results of questionnaires from the independent departments revealed that in all three countries lectures were more prevalent (A: n = 0; CH: n = 4; D: n = 6) than practical training in nursing homes (A: n = 0; CH: n = 3; D: n = 6). Conclusion: Considering the demographical shift which is leading to an increasing proportion of elderly in the population, the weighting of gerodontology in the undergraduate dental curriculum should be considered for revision in Austria and Germany.     

Hesperetin mitigates acrolein-induced apoptosis in lung cells in vitro and in vivo

Objectives: A number of studies have suggested that acrolein-induced lung injury and pulmonary diseases are associated with the depletion of antioxidants and the production of reactive oxygen species. Therefore, compounds that scavenge reactive oxygen species may exert protective effects against acrolein-induced apoptosis. Because hesperetin, a natural flavonoid, has been reported to have an antioxidant activity, we investigated the effect of hesperitin against acrolein-induced apoptosis of lung cells.

Methods: We evaluated the protective role of hesperetin in acrolein-induced lung injury using Lewis lung carcinoma (LLC) cells and mice.

Results: Upon exposure of LLC cells and mice to acrolein, hesperetin ameliorated the lung inbjury through attenuation of oxidative stress.

Conclusion: In the present report, we demonstrate that hesperetin exhibits a protective effect against acrolein-induced apoptosis of lung cells in both in vitro and in vivo models. Our study provides a useful model to investigate the potential application of hesperetin for the prevention of lung diseases associated with acrolein toxicity.     

Fatty acids and the selective alteration of in vitro proliferation in human fibroblast and guinea-pig smooth-muscle cells

Summary Human-foreskin fibroblast (HF) and guinea-pig aorta smooth-muscle (SM) cultures were treated with several saturated and unsaturated fatty acids. Relative plating efficiencies were used to determine the proliferative response to each treatment. At low concentrations (16 to 18 μm), proliferation in HF cultures was inhibited by 8,11,14-eicosatrienoic acid (20:3), and stimulated by both 5,8,11,14-eicosatetraenoic acid (20:4) and 9-octadecenoic acid (18:1). At these levels, proliferation in SM cultures was unchanged by 20:3, inhibited by 20:4, and enhanced by 18:1. At higher concentrations (80 to 90 μm), HF cultures were inhibited by all three unsaturated fatty acids. At these same concentrations, proliferation in SM cultures was inhibited by 20:3 and 20:4, whereas 18:1 continued to stimulate proliferation. Thus proliferative response was a specific effect of the fatty acid used, its concentration, and the cell line involved. Further treatment of SM cultures by tetradecanoic acid (14:0), hexadecanoic acid (16:0), and octadecanoic acid (18:0) showed that their relative abilities to inhibit cell proliferation increased with increasing chain length. Concentrations required for the effective inhibition of proliferation in SM cultures by 14:0, 16:0 and 18:0 were 220 μm, 95μm and 18μm, respectively. The fatty acids used in these studies are all endogenous components of sera used as growth supplements in in vitro systems. Their roles as prostaglandin and hydroperoxy fatty-acid precursors (20:3 and 20:4), inhibitors of prostaglandin biosynthesis (18:1), or as calcium ionophores (14:0, 16:0, and 18:0) may allow them to function as endogenous controls of cell proliferation. This work was supported in part by National Heart and Lung Institute Grant HL-11897.     

Dosing time and sex-related differences in the pharmacokinetics of cefodizime and in the circadian cortisol rhythm

Two g cefodizime i.v. administration at 00:00, 06:00, 12:00 and 18:00 respectively, to 8 male and 8 female, young healthy volunteers, has shown: 1. a sex-related difference in both plasma (AUC) and total cumulative excretion of the agent with larger values in females than in males; 2. a dosing time-related difference in plasma (AUC) with the largest values for Rx at 00:00 and lowest for Rx at 18:00 in both males and females; 3. a dosing time-related difference in urinary concentration of cefodizime with largest values for Rx at 06:00 and lowest for Rx at 12:00. These urinary changes were highly correlated with changes in AUC for each dosing time; 4. no dosing time-related changes were observed for plasma T1/2 as well as cumulative urinary excretion of cefodizime; 5. curve patterns of plasma cortisol had similar aspects for both control and Rx at 00:00 with no sex-related differences. Curve patterns differed from control for other dosing times (p less than 0.005 to p less than 0.001 with ANOVA tests).     

Intestinal Lipid Esterification and Aging in Mice and Rats

The effects of aging on lipid absorption, particularly on fatty acid glycerophospholipid and triacylglycerol esterification, were investigated in 2.5-,12- and 24-month-old mice and rats. Two intestinal mucosa microsomal enzymes, involved in the dietary fatty acid absorption, were assayed:acylCoA:2-monoacylglycerol acyltransferase and acylCoA:1-lysophosphatidylcholine acyltransferase. In both mice and rats, the activities of both enzymes varied with the nature of the acyl-CoA. Indeed acylCoa:2-monoacylglycerol acyltransferase activities were significantly higher with oleoyl-CoA and linoleoyl-CoA than with palmitoyl-CoA and arachidonoyl-CoA, while acylCoA:1-lysophosphatidylcholine acyltransferase activities were highest with arachidonoyl-CoA. AcylCoA:2-monoacylglycerol acyltransferase activity did not decrease significantly with aging in mice or rats, whatever the acyl-CoA used. In contrast, acylCoA:1-lysophosphatidylcholine acyltransferase activity in the 24-month-old rats was significantly lower (−47 %) than in 2.5-month-old rats, with oleoyl-CoA, linoleoyl-CoA and arachidonoyl-CoA. Simultaneously we observed that less glycerophospholipid esterification of oleic and linoleic acid occurs in older rats than in 2.5-month-old rats.     

Bacterial populations and processes involved in acetate and propionate consumption in anoxic brackish sediment

Bacterial populations and pathways involved in acetate and propionate consumption were studied in anoxic brackish sediment from the Grosser Jasmunder Bodden, German Baltic Sea. Uptake of acetate and propionate from the porewater was studied using stable carbon isotope-labeled compounds. Labeled acetate was not produced as an intermediate during propionate uptake experiments, and propionate consumption was not affected by the addition of acetate. In parallel, incorporation of labeled acetate and propionate into phospholipid-derived fatty acids (PLFA) was studied to indicate bacterial populations involved in the consumption of these substrates. The (13)C-acetate label was mainly recovered in even-numbered PLFA (16:1omega7c, 16:0 and 18:1omega7c). In contrast, primarily odd-numbered PLFA (a15:0, 15:0, 17:1omega6 and 17:0) and the even-numbered i16:0 were labeled after incubation with (13)C-propionate. Although single PLFA labeled with propionate are commonly found in sulfate reducers, the complete PLFA-labeling pattern does not resemble any of the know strains. However, the acetate-labeling pattern is similar to Desulfotomaculum acetoxidans and Desulfofrigus spp., two acetate-consuming, sulfate reducers. In conclusion, our data suggest that acetate and propionate were predominantly consumed by different, specialized groups of sulfate-reducing bacteria.     

Molecular Species of Diacylglycerols and Phosphoglycerides and the Postmortem Changes in the Molecular Species of Diacylglycerols in Rat Brains

The molecular species of 1,2-diacyl-sn-glycerol (DAG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylinositol 4-phosphate (PIP), and phosphatidylinositol 4,5-bisphosphate (PIP2) from brains of adult rats (weighing 150 g) were determined. The DAG, isolated from brain lipid extracts by TLC, was benzoylated, and the molecular species of the purified benzoylated derivatives were separated from each other by reverse-phase HPLC. The total amount and the concentration of each species were quantified by using 1,2-distearoyl-sn-glycerol (18:0-18:0) as an internal standard. About 30 different molecular species containing different fatty acids at the sn-1 and sn-2 positions of DAG were identified in rat brains (1 min postmortem), and the predominant ones were 18:0-20:4 (35%), 16:0-18:1 (15%), 16:0-16:0 (9%), and 16:0-20:4 (8%). The molecular species of PC, PE, PS, and PI were determined by hydrolyzing the lipids with phospholipase C to DAG, which was then benzoylated and subjected to reverse-phase HPLC. PIP and PIP2 were first dephosphorylated to PI with alkaline phosphatase before hydrolysis by phospholipase C. The molecular species composition of phosphoinositides showed predominantly the 18:0-20:4 species (50% in PI and approximately 65% in PIP and PIP2). PS contained mainly the 18:0-22:6 (42%) and 18:0-18:1 (24%) species. PE was mainly composed of the 18:0-20:4 (22%), 18:0-22:6 (18%), 16:0-18:1 (15%), and 18:0-18:1 (15%) species. In PC the main molecular species were 16:0-18:1 (36%), 16:0-16:0 (19%), and 18:0-18:1 (14%). Studies on postmortem brains (30 s to 30 min) showed a rapid increase in the total amount (from 40-50 nmol/g in 0 min to 210-290 nmol/g in 30 min) and in all the molecular species of DAG. Comparatively larger increases (seven- to 10-fold) were found for the 18:0-20:4 and 16:0-20:4 species. Comparison of DAG species with the molecular species of different glycerolipids indicated that the rapid postmortem increase in content of DAG was mainly due to the breakdown of phosphoinositides. However, a slow but continuous breakdown of PC to DAG was also observed.     

Changes in moorland and heathland bird abundance in southwest England in relation to environmental change

Capsule: Population changes of many moorland and heathland birds in southwest England show associations with environmental change, and the area supports notable breeding populations of species of conservation concern.

Aims: To quantify changes in moorland and heathland breeding bird abundance in relation to changes in environmental variables.

Methods: A two-visit moorland bird survey method was used to estimate the abundance of 23 target bird species in 2008 and 2014 in Exmoor National Park, southwest England. Data on changes in 25 environmental variables over the same period were used to test associations between changes in bird abundance and environmental change.

Results: Fourteen species increased in abundance and nine decreased. Breeding species which wintered on or close to Exmoor were less likely to show negative population changes than species which migrated to winter in southern Europe or Africa. Change in abundance of 18 species was associated with change in at least one environmental variable, and these relationships were broadly consistent with the known ecology of these species.

Conclusion: Although some moorland species have declined or gone locally extinct, this area of moorland and heathland in southwest England remains an important stronghold for several species of high conservation concern. The maintenance of semi-natural moorland and heathland habitats in areas such as Exmoor may provide important refuges for such species, both now and in the future.     

Factor VIII activity and factor VIII-associated antigen in healthy newborns and in newborns with stressing perinatal factors

Factor VIII coagulation activity (VIII:C) and factor VIII associated antigen (VIII:AGN) were determined in healthy newborns and in children with charging perinatal factors ("risk children"). VIII:C values of healthy newborns may be compared with those of grown-ups with normal coagulation. Risk children have somewhat higher values than newborns, the difference, however, being statistically not significant. The concentration of VIII:AGN is clearly increased in both groups on the first day of life. Moreover, VIII:AGN is being eliminated more slowly in risk children. The increased VIII:AGN concentrations are considered as a sequel of stress conditions caused by birth, whereas the discrepancy between VIII:C and VIII:AGN is due to a thrombin effect.     

Seasonal variation in plasma lipids and lipases in young healthy humans

Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year.

In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am.

Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude).

Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter.

These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.     

The sex ratios of bovine embryos produced in vivo and in vitro

The male:female ratio of developing bovine embryos produced and allowed to develop in vitro and in vivo was determined retrospectively from the cytogenetic analysis of 804 embyos. The overall male:female ratio of the 307 (38%) embryos that could be sexed was 162 (52.8%):145 (47.2%) and did not differ (P>0.05) from the expected 1:1 ratio. Among premorula stage embryos produced in vivo (n = 66) and in vitro (n = 30), the ratios were 1.2:1 and 0.76:1, respectively. Among morulae and blastocysts produced in vivo (n = 74), produced and cultured in vitro (n = 106, and produced in vitro and cultured in vivo (n = 31), the ratios were 1.11:1, 1.3:1 and 0.94:1, respectively, none of which differed significantly from 1:1. There was no difference (P>0.05) in the number of cells or mitotic index between male and female morulae and blastocyst, respectively.     

Expression of meadowfoam Des5 and FAE1 genes in yeast and in transgenic soybean somatic embryos,and their roles in fatty acid modification

Meadowfoam (Limnanthes spp.) species are unique in that their seeds are rich in the unusual fatty acids Δ⁵-eicosenoic acid (C20:1^Δ5) and the diene, C22:2^{Δ5, Δ13}. Previously the cloning of Δ⁵ desaturase (Des5) and fatty acid elongase 1 (FAE1) meadowfoam genes and their expression in soybean were reported. Here, we present the first successful expression of the Limnanthes Des5 in yeast, resulting in the desaturation of C16:0, C18:0 and C20:0 to their corresponding cis Δ⁵ isomers. In soybean (Glycine max L.), Limnanthes Des5/FAE1 double transformant somatic embryos fed with radiolabeled C14:0 or C16:0 could elongate these substrates to C18:0, C20:0 and C22:0 and C24:0. However, radiolabeled C18:1^Δ9 or C20:1^Δ11 were not elongated to their respective monounsaturated very long-chain products, confirming that the cloned Limnanthes FAE1 homolog gene product was specific for elongating saturated fatty acids. To understand better the biosynthetic pathway for C22:2^{Δ5, Δ13}, soybean somatic embryos transformed with the Des5 cDNA were fed in culture with 〚1-¹⁴C〛C 22:1^Δ13 fatty acid, which resulted in the biosynthesis of 〚1-¹⁴C〛-labeled C22:2^{Δ5, Δ13}. Cell-free preparations enriched with detergent-solubilized Δ⁵ desaturase activity extracted from both developing meadowfoam seeds and from Des5 transgenic soybean embryos, produced ¹⁴C-22:2^{Δ5, Δ13} when supplied with 〚1-¹⁴C〛 C22:1-CoA. Thus, both the in vivo and in vitro experiments showed that the biosynthesis of C22:2^{Δ5, Δ13} can occur in somatic soybean embryos transformed with the Limnanthes Des5 cDNA, and confirmed that the pathway for C22:2 biosynthesis in meadowfoam involves further desaturation of erucoyl-CoA by a Δ⁵-regiospecific desaturase.     

Lipids and fatty acids in the copepod Jaschnovia brevis (Jaschnov) and in particulates from Arctic waters

The small, sub-ice copepod Jaschnovia brevis is rich in triacylglycerols, suggesting a feeding behaviour not constrained to the seasonal phytoplankton bloom. The copepod's triacylglycerol reserves contain: the diatom biomarkers 16:1n-7 (23.9%), 20:5n-3 (8.5%) and C16 PUFA (1.3%), the flagellate biomarkers 18:4n-3 (3.7%) and 22:6n-3 (3.3%), and the Calanus copepod biomarkers 20:1n-9 (7.7%) and 22:1n-11 (6.2%). Total lipid from particulates in the water column contained polar lipid (45.0%), wax esters (24.9%) and triacylglycerols (11.2%) as major components. The total lipids in the particulates were rich in 18:1n-9 (31.5%) and 16:0 (21.2%), and relatively rich in 18:0 (7.8%) and 18:2n-6 (9.2%). The triacylglycerols in the particulates contained 16:1n-7 (20.7%), C16 PUFA (4.1%), 18:4n-3 (1.9%), 20:5n-3 (3.6%), 22:6n-3 (1.9%), 20:1n-9 (5.2%) and 22:1n-11 (3.9%). The polar lipids in the particulates contained 16:1n-7 (17.3%), C16 PUFA (7.8%), 18:4n-3 (3.3%), 20:5n-3 (14.5%) and 22:6n-3 (9.6%). The fatty alcohols in the wax esters of the particulates were mainly 16:0 (11.3%), 20:1n-9 (21.1%) and 22:1n-11 (30.6%). The nature of the particulates, their possible origin in living and non-living material, and their role in the nutrition of J. brevis are discussed.     

Glycosylation and its implications in breast cancer

Introduction: For decades, the role of glycans and glycoproteins in the progression of breast cancer and other cancers have been evaluated. Through extensive studies focused on elucidating the biological functions of glycosylation, researchers have been able to implicate alterations in these functions to tumor formation and metastasis.

Areas covered: In this review, we summarize how changes in glycosylation are associated with tumorigenesis, with emphasis on breast cancers. An overview of the changes in N-linked and O-linked glycans associated with breast cancer tumors and biofluids are described. Recent advances in glycomics are emphasized in the context of continuing to decipher the glycosylation changes associated with breast cancer progression.

Expert opinion: While changes in glycosylation have been studied in breast cancer for many years, the clinical relevance of these studies has been limited. This reflects the inherent biological and clinical heterogeneity of breast cancers. Glycomics analysis lags behind the advances in genomics and proteomics, but new approaches are emerging. A summary of known glycosylation changes associated with breast cancer is necessary to implement new findings in the context of clinical outcomes and therapeutic strategies. A better understanding of the dynamics of tumor and immune glycosylation is critical to improving emerging immunotherapeutic treatments.     

Novel peptidoglycans in Caulobacter and Asticcacaulis spp.

Peptidoglycan sacculi free of poly-beta-hydroxybutyric acid were prepared from whole cells of four species of Caulobacter and two species of Asticcacaluis and from morphological mutants of Caulobacter crescentus and Caulobacter leidyi. Acid hydrolysates of the sacculi were analyzed quantitatively, and each of the hydrolysates was found to contain significant amounts of only five ninhydrin-reactive compounds: alanine, glutamic acid, alpha , omega-diaminopimelic acid, muramic acid, and glucosamine. Four types of peptidoglycans were distinguishable on the basis of the molar ratios among these five compounds. The respective ratios were as follows: in C. leidyi, 2:1:1:1:0.8; in Asticcacaulis biprosthecum, 1.7:1.6:1.1:0.7; in the cells of the remaining species, 2:1:1:1.2:0.8; and in stalks shed by the abscission mutant 2NY66, 2:1:1:1:1.67. Thus, in addition to some species differences among these caulobacters, it was found that the peptidoglycan sacculus of the stalked C. crescentus cell is chemically differentiated; the cellular peptidoglycan is richer in muramic acid than is the peptidoglycan of typical gram-negative bacteria, and the peptidoglycan of the stalk is correspondingly rich in glucosamine. Empirical formulas for the repeating units of the peptidoglycans have been inferred on the basis of the molar ratios of their amino components.     

Nature and nurture in the dynamics of C, N and P during litter decomposition in Canadian forests

We measured changes in carbon (C), nitrogen (N) and phosphorus (P) concentrations and mass of 10 foliar litters decomposing over 12 years at 21 sites across Canada, ranging from subarctic to temperate, to evaluate the influence of litter quality (nature) and forest floor (nurture) on N and P dynamics. Most litters lost P faster than N, relative to C, except in one litter which had a high initial C:P quotient (2,122). Net N loss occurred at mass C:N quotients of between 33 and 68, positively correlated with the C:N quotient in the original litter, and net P loss likely occurred at C:P quotients between 800 and 1,200. Forest floor properties also influenced N and P dynamics: the higher the C:N or C:P quotient in the surface soil organic matter, the smaller the proportion of initial N or P left in the decomposing litter, relative to C. There was a convergence of C:N and C:P quotients as the litters decomposed, with an overall mass ratio of 427:17:1 when the litters reached 20% original C remaining. These results, covering a wide range of sites and litters and thus decomposition rates, showed that the C:N:P quotients followed similar trajectories and converged as the litters decomposed. The relative loss of N and P was affected by both the initial litter nutrient concentration and the chemistry of the site forest floor, with the former being more important than the latter, resulting in spatial variations in nutrient content of the forest floor.     

Continuity and Change in Modern India

A Caste in a Changing World: The Chitrapur Saraswat Brahmans, 1700–1935 . Frank F. Conlon. Sponsored by the Center for South and Southeast Asia Studies. Berkeley: University of California Press, 1977. xv + 255 pp. $15.00 (cloth).
Shanti Nagar: The Effects of Urbanization in a Village in North India. Vol. 1: Social Organization . Stanley A. Freed and Ruth S. Freed. Anthropological Papers, 53, Part 1. New York: The American Museum of Natural History, 1976. 254 pp. $13.85 (paper).
Family and Social Change in Modern India . Giri Raj Gupta , ed. Main Currents in Indian Sociology, 2. Durham, N.C.: Carolina Academic Press, 1976. xxxiv + 263 pp. n.p. (cloth).
Caste, Class and Democracy: Changes in a Stratification System . Vijai P. Singh. Cambridge, Mass.: Schenkman, 1976. viii + 158 pp. $12.50 (cloth), $5.95 (paper).
Dimensions of Social Change in India . M. N. Srinivas, S. Seshaiah , and V. S. Parthasarathy , eds. New Delhi: Allied Publishers Private, 1977. xiii + 518 pp. Rs 60.00 (cloth).