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Discrete element modelling (DEM) is one of the most efficient computational approaches to the fracture processes of heterogeneous materials on mesoscopic scales. From the dynamics of single crack propagation through the statistics of crack ensembles to the rapid fragmentation of materials DEM had a substantial contribution to our understanding over the past decades. Recently, the combination of DEM with other simulation techniques like Finite Element Modelling further extended the field of applicability. In this paper we briefly review the motivations and basic idea behind the DEM approach to cohesive particulate matter and then we give an overview of on-going developments and applications of the method focusing on two fields where recent success has been achieved. We discuss current challenges of this rapidly evolving field and outline possible future perspectives and debates.

AbstractDiagnosing the evolution of laser-generated high energy density (HED) systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions. Talbot–Lau interferometry constitutes a promising tool, since it permits simultaneous single-shot X-ray radiography and phase-contrast imaging of dense plasmas. We present the results of an experiment at OMEGA EP that aims to probe the ablation front of a laser-irradiated foil using a Talbot–Lau X-ray interferometer. A polystyrene (CH) foil was irradiated by a laser of 133 J, 1 ns and probed with 8 keV laser-produced backlighter radiation from Cu foils driven by a short-pulse laser (153 J, 11 ps). The ablation front interferograms were processed in combination with a set of reference images obtained ex situusing phase-stepping. We managed to obtain attenuation and phase-shift images of a laser-irradiated foil for electron densities above ${10}^{22}\;{\mathrm{cm}}^{-3}$ . These results showcase the capabilities of Talbot–Lau X-ray diagnostic methods to diagnose HED laser-generated plasmas through high-resolution imaging.

Langes Leben mit kontrollierter Bewegung: Maßgeschneiderte Proteinnanomaschinen mit eindeutigen und anpassbaren Funktionen ermöglichen eine Kontrolle der Bewegung auf nano‐ bis mikroskaligen Biohybrid‐Funktionseinheiten. Myosinmotoren (im Bild ist ein dimerer gezeigt) mit optimierten Eigenschaften hinsichtlich Stabilität und Steuerung, einschließlich schaltbarer Prozessivität und Feinsteuerung der Geschwindigkeit der Bewegung, wurden nun entwickelt.

Abstract: Information on genetic diversity and genetic relationships among genotypes of Brassica carinata is currently limited. The objectives of this study were to evaluate patterns and levels of genetic diversity in B. carinata based on amplified fragment length polymorphisms (AFLP) as compared with Brassica juncea and Brassica nigra, and to evaluate agronomic and seed quality data for plants grown in the field in western Canada. A total of 296 AFLP bands were generated from four primer pair combinations and scored for presence/absence in 66, 20 and 7 accessions of B. carinata, B. juncea and B. nigra, respectively. B. carinata was less genetically diverse than the other two species. Differences in diversity were evident in the proportion of polymorphic loci within each species: 23, 35 and 50% for B. carinata, B. nigra and B. juncea, respectively. Pair-wise similarity measures based on the Jaccard coefficient were highest among accessions of B. carinata and showed the narrowest range: 0.911 (0.810–0.981) compared to B. nigra: 0.569 (0.438–0.660) and B. juncea: 0.715 (0.345–0.951). AFLP-based genetic distance information can be used by plant breeders to select diverse genotypes. AFLPs are also useful for fingerprinting cultivars and two primer pair combinations were sufficient to uniquely identify all the accessions of B. carinata. More variation among accessions was identified in the agronomic trial than had previously been described in studies of B. carinata in western Canada, but the data were too limited to draw conclusions regarding specific accessions. Overall, the findings were in agreement with other published work describing the favourable agronomic potential of this species.

The liquid crystalline and selected physical properties of some vanadyl and manganese(III)-porphyrin-TCNE complexes are discussed. These materials form linear chains from a magnetic point of view and columnar discotic LC phases. Some of the manganese complexes exhibit a bulk magnetic phase below ∼20 K. The discussed materials are studied by means of DSC, X-ray powder diffraction, dielectric spectroscopy, reversal current characterization and magnetic susceptibility measurements. A broader view on some physical properties of columnar paramagnetic metallomesogens is given.

Abstract: Heat flow to [Fe(bzimpy)2](ClO4)2⋅0.25H2O complex (bzimpy=2,6-bis(benzimidazol-2-yl)pyridine) (I) was measured between 300 and 460 K by differential scanning calorimetry. This exhibits a well-developed peak characteristic of the first-order phase transitions at temperature 403 K. The enthalpy and entropy of transition from low-spin to high-spin state has been determined to be ΔH=17 kJ mol−1 and ΔS=43.0 Jmol−1 K−1. Heat flow to [Fe(bzimpy−1H)2]⋅H2O complex (bzimpy −1H=deprotonated bzimpy) (II) was measured between 300 and 580 K. The spin crossover in this system is accompanied with liberation of crystal water on the first heating. To monitor the structural changes during the spin crossover, powder diffraction data have been collected as a function of temperature.

We investigated one-dimensional donor–acceptor chains, built of [Mn^IIIR4TPP]⁺ cations (R4TPP = substituted tetraphenylporphyrin) and [TCNE]^— radical anions (TCNE = tetracyanoethylene) which can exhibit a phase transition to a three-dimensional magnetically ordered state at low temperatures. This transition can be followed by measurements of the dynamic magnetic susceptibility which in this case shows a maximum in the real as well as in the imaginary part. Magnetization measurements give information about characteristic properties like remanence and coercivity (hysteresis), and spin flop behaviour. Despite the fact of large interchain distances between the columns one explanation for the magnetic ordering is a dipolar interaction in combination with the high magnetic anisotropy of the Mn^III ions.

Arabidopsis and other Brassicaceae produce an enormous diversity of aliphatic glucosinolates, a group of methionine (Met)-derived plant secondary compounds containing a beta-thio-glucose moiety, a sulfonated oxime, and a variable side chain. We fine-scale mapped GSL-ELONG, a locus controlling variation in the side-chain length of aliphatic glucosinolates. Within this locus, a polymorphic gene was identified that determines whether Met is extended predominantly by either one or by two methylene groups to produce aliphatic glucosinolates with either three- or four-carbon side chains. Two allelic mutants deficient in four-carbon side-chain glucosinolates were shown to contain independent missense mutations within this gene. In cell-free enzyme assays, a heterologously expressed cDNA from this locus was capable of condensing 2-oxo-4-methylthiobutanoic acid with acetyl-coenzyme A, the initial reaction in Met chain elongation. The gene methylthioalkylmalate synthase1 (MAM1) is a member of a gene family sharing approximately 60% amino acid sequence similarity with 2-isopropylmalate synthase, an enzyme of leucine biosynthesis that condenses 2-oxo-3-methylbutanoate with acetyl-coenzyme A.

We have investigated Mn(III)–porphyrin–TCNE complexes showing peculiar magnetic properties at low temperatures. The tetraphenylporphyrin ligand is substituted on the periphery of the phenyl rings with different groups. Static and dynamic susceptibility measurements have been carried out on the samples.

Most human adults carry the Epstein-Barr virus (EBV) and develop immunological memory against the structural and the virus-encoded cellular proteins. The EBV nuclear antigen 6 (EBNA6) elicits cytotoxic T cell responses and it also maintains a persistent antibody response. The majority of sera from EBV-seropositive individuals reacts with a synthetic peptide, p63, comprising 21 amino acids of a repetitive region of EBNA6. CD4(+) T lymphocytes, with specificity for p63, could be recalled from the T cell repertoire of EBV carriers that expressed certain HLA-DR allotypes which were identified as good binders of p63 by an in vitro flow cytometric assay. Analysis of the HLA-DR/p63 interaction by molecular mechanics calculations indicated the presence of multiple overlapping epitopes which were predicted to bind in a HLA-DRB1 allo- and subtype-specific manner. Specific activation of p63-selected long-term CD4(+) T cell cultures resulted in a proliferative response, in the production of IL-2 and in the secretion of high levels of tumor necrosis factor as measured by bioassays. Proliferation and cytokine production of p63-specific T cells could be induced by p63-loaded HLA-DR-matched antigen-presenting cells and by B cells co-expressing relevant HLA-DR molecules and EBNA6. Our results show that peptides of an EBNA6 repeat region induce CD4(+) T cells which can react with EBNA6-carrying cells in many individuals. We suggest that these T(h) cells may be important in conditioning dendritic cells for initiation potent virus-specific immune responses, provide help for EBV-specific B cells, drive IgG isotype switch and support the sustained effector function of memory cytotoxic T lymphocytes.

Epstein-Barr virus (EBV) episomal DNA is extensively methylated in Burkitt lymphoma derived cell lines. In this study we examined whether lytic viral cycle reactivation is dependent on demethylation of critical viral genes. Viral replication was induced in the Burkitt’s lymphoma cell line Daudi by the combination of 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium-butyrate. Two regions necessary for EBV replication, the BZLF1 immediate early region and the origin of lytic cycle replication (ori Lyt) were demethylated during the early phase of the lytic virus cycle. Demethylation was observed while production of new (unmethylated) viral DNA was blocked by phosphonoformic acid (PFA). This suggests that demethylation, which may be instrumental for the onset of the lytic cycle, is an active process independent of viral DNA repli- cation.

Übersicht Aus den Verlusten und der Geometrie werden der Temperaturverlauf im Zahn, der Stromdichteverlauf durch die Nutwand und die Wicklungserwärmung gegenüber dem als Isotherme betrachteten Nutgrundkreis berechnet. Damit können die thermischen Folgen jeder Änderung im Bereich Ständerzahn-Ständernut vorausbestimmt werden. Dies wird am Beispiel der Nutformoptimierung bei konstanter Nutfläche gezeigt.

Infectious salmon anemia (ISA) virus is the cause of infectious salmon anemia in farmed Atlantic salmon. The virus has been shown to contain RNA with structural characteristics similar to those of accepted members of the Orthomyxoviridae. Further biochemical, physiochemical, and morphological characterization of ISA virus was undertaken to clarify its taxonomic position. The virus was found to be sensitive to chloroform, heat, and low pH and agglutinated erythrocytes from fish. Erythrocytes from mammals or birds were not agglutinated. Receptor-destroying enzyme activity was detected, and the nature of this enzyme was suggested to be an acetylesterase. The buoyant density of the virus was 1.18 g/ml in sucrose and CsCl gradients. The maximum rate of virus replication was observed at 15 degrees C, while no virus was produced at 25 degrees C. Actinomycin D inhibited viral replication, and viral antigen was detected in nuclei by immunofluorescence. The addition of trypsin to the culture medium during virus replication had a beneficial effect on virus replication. ISA virus contains four major polypeptides with estimated molecular sizes of 71, 53, 43, and 24 kDa. Electron microscopy revealed structures closely resembling the nucleocapsids of influenza virus. Mushroom-shaped surface projections were a distinctive morphological feature, which differed from the rod-shaped hemagglutinin projections of the influenza viruses. The data reported here support the relationship of ISA virus to the Orthomyxoviridae, although ISA virus differs from influenza viruses in some morphological characteristics and in showing restricted hemagglutination, in different specificity of the receptor-destroying enzyme, in different polypeptide profile, in being unable to replicate at temperatures above 25 degrees C, and in host range.

Standard synthetic peptide preparations contain numerous peptidic byproducts in small amounts, which may be efficiently recognized by cytotoxic T lymphocytes (CTL). Recognition patterns of such peptide mixtures by CTL may serve as a kind of fingerprint for CTL fine specificity. Three types of H-2Db-restricted CTL were compared in this way. CTL primed in vivo either with A/PR/8/34 influenza virus or with a synthetic lipopeptide vaccine prepared from influenza nucleoprotein (NP) peptide 365-380 showed identical fine specificity. Both recognize virus-infected cells. In contrast, CTL primed in vitro with NP 365-380 had a different fine specificity and they did not recognize virus-infected cells. Most significantly, the two in vivo primed CTL types efficiently recognized the natural viral nonapeptide NP 366-374 presented by virus-infected H-2b cells, whereas the in vitro primed CTL failed to do so.

Virus-specific cytotoxic T lymphocytes (CTL) recognize virus-derived peptides presented by major histocompatibility complex (MHC) class I molecules on virus-infected cells. Such peptides have been isolated from infected cells and were compared to synthetic peptides. We found previously the Kd- or Db-restricted natural influenza nucleoprotein peptides to coelute on reversed phase high performance liquid chromatography columns with certain peptidic by-products present in synthetic peptide preparations. Here we show by extensive biochemical and immunological comparison that the natural peptides in all respects behave as the surmised synthetic nonapeptides, and thus, must be identical to them. The absolute amounts of these natural peptides contained in infected cells could be determined to be between 220 and 540 copies by comparing with defined amounts of pure synthetic nonapeptides. The comparison of the natural Kd-restricted peptide with published synthetic peptides known to contain other Kd-restricted CTL epitopes suggested a new MHC allele-specific T cell epitope forecast method, based on the defined length of nine amino acid residues and on critical amino acid residues at the second and the last position.

The genome of infectious salmon anemia virus (ISAV), which infects farmed Atlantic salmon (Salmo salar L.), is characterized here. The virus has an RNA genome, as shown by using specific DNA virus metabolic inhibitors and radioactive in vivo labeling of ISAV nucleic acid. Electrophoresis of [14C]uridine-labeled ISAV RNA revealed that the ISAV genome is segmented. The genome consists of eight segments that range from 1.0 to 2.3 kb, with a total molecular size of approximately 14.5 kb. One ISAV-specific molecular clone, corresponding to the smallest genome segment, was obtained by cDNA cloning of mRNA from an ISAV-infected cell culture. This clone gave a positive hybridization signal on Northern blots of pelleted ISAV. Pretreatment of the ISAV pellet with RNase A resulted in the disappearance of the positive hybridization signal, demonstrating that the genome is single stranded. Reverse transcriptase PCR with primers corresponding to sequences from the molecular clone and target RNA from ISAV-infected and noninfected fish tissues gave specific positive reactions. Alignments of the nucleotide sequence of the molecular clone did not reveal significant homology with any other available sequence in databases. However, the data presented here, together with morphological and replicational properties previously described, indicate that ISAV has a strong resemblance to members of the Orthomyxoviridae family. This is the first thoroughly characterized orthomyxo-like virus isolated from a teleost.

Nonproductive infection of B lymphocytes by Epstein-Barr virus (EBV) is associated with a highly restricted expression of viral genes. In growth-transformed lymphoblastoid cell lines, the products of these genes include a complex of at least six EBV nuclear antigens (EBNAs) (EBNA-1 through EBNA-6) and one membrane protein (latent membrane protein [LMP]). EBV-carrying Burkitt's lymphoma (BL) biopsies and derived cell lines that have retained a representative phenotype (group I BL lines) express only EBNA-1 (M. Rowe, D. T. Rowe, C. D. Gregory, L. S. Young, P. J. Farrell, H. Rupani, and A. B. Rickinson, EMBO J. 6:2743-2751, 1987). We have found that EBNA-2 through EBNA-6 and LMP can be up regulated by treating the group I BL line Rael with the DNA-demethylating agent 5-azacytidine (5-AzaC). The drug acted in a time- and dose-dependent manner. EBNA-2-positive cells were detected by anti-complement immunofluorescence staining just 12 h after addition of 4 microM 5-AzaC and reached a maximum number at 72 h, when up to 75% of the population was positive. EBNA-2, EBNA-3, EBNA-4, EBNA-4, EBNA-6, and LMP were demonstrated immunoblots starting at 48 h. The EBV-encoded early antigens and viral capsid antigens were also induced but at a lower level. EBNA-2 and the lytic cycle-associated antigens appeared with a different time course and in largely nonoverlapping cell subpopulations, as demonstrated by double fluorescence staining. Thus, EBNA-2 expression was not restricted to lytically infected cells, nor was EBNA-2 required for entry into the lytic cycle. The coding and regulatory sequences of EBNA-2 and LMP were found to be highly methylated in Rael cells and were, as expected, demethylated after 5-AzaC treatment. These findings suggest that DNA methylation may participate in the regulation of growth transformation-associated viral genes in BL cells.

In vitro infection of human B lymphocytes with Epstein-Barr virus (EBV) results in establishment of B lymphoblastoid cell lines that reflect normal B cell phenotypes. In this study we have investigated whether immature B cells from fetal bone marrow and liver can serve as targets for EBV. The fetal bone marrow cells were readily transformed by EBV. Among the resulting cell lines, five were surface Ig (sIg)-negative. Three B cell-associated antigens defined by monoclonal antibodies were expressed to the same extent on the fetal cell lines, whether they belonged to the sIg- or sIg+ group. The various differentiation stages that these cell lines may represent are discussed.

The consensus motifs of HLA-Cw3, -Cw4, -Cw6, and -Cw7 ligands were determined by pool sequencing. Together with information obtained by sequencing of some prominent individual peptides, the results indicate the following: (i) all four HLA-C molecules are associated with peptides. (ii) These peptides adhere to allele-specific motifs that are similar to those of to HLA-A or -B molecules; they have a preferred length of nine amino acids and an anchor residue at the C terminus. (iii) All four HLA-C molecules analyzed exhibit related peptide motifs, although each allelic product shows individual characteristics in fine specificity. (iv) Processing and origin of peptides appear not to be different from that of other class I molecules. (v) No obvious difference at C-terminal position 9 was present in the peptides isolated from the two dimorphic variants of HLA-C that determine dominant resistance to natural killer NK1-specific cells (HLA-Cw4, -Cw6) or to NK2-specific cells (HLA-Cw3, -Cw7) and that differ in two residues in or near the pocket at position 9.

Seven virus-coded proteins, the nuclear proteins EBNA-1 to EBNA-6 and the latent membrane protein (LMP), are regularly expressed in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines. In nasopharyngeal carcinoma (NPC), only EBNA-1 is regularly expressed; LMP is detected in about 65% of the tumors. In Burkitt's lymphoma tumors only EBNA-1 is expressed. We have recently shown that the methylation patterns of the EBV genome varied between these cell types. In virally transformed lymphoblastoid cell lines of normal origin, the EBV DNA is completely unmethylated. In contrast, in the Burkitt's lymphoma-derived cell line Rael and in a nude mouse-passaged NPC tumor, C15, there was an extensive methylation of CpG pairs. The methylation extended into the coding regions of the two expressed genes, EBNA-1 (in both tumor types) and LMP (in C15). Two presumptive control regions were exempted from this overall methylation: the oriP that contains both an origin of DNA replication and an EBNA-1-dependent enhancer and the 5'-flanking region of the BNLF-1 open reading frame that codes for LMP. The latter was only exempted in the LMP expressing NPC. We have now investigated the relation between expression of LMP and methylation of DNA in the 5'-flanking 1 kb region of BNLF-1, coding for LMP. LMP was methylated in 3 of 12 NPC biopsies that did not express LMP but was partially or totally unmethylated in the remaining 9 that expressed the protein. The three BNLF-1 exons were highly methylated in all the tumors. The oriP region was unmethylated in all the tumors, as in the previously studied Rael cell line and nude mouse-passaged NPC. Also, the BamHI W enhancer region involved in the expression of EBNA nuclear proteins was methylated. None of the biopsies expressed EBNA-2. Our data show that the EBV genomes are highly methylated in NPC tumors. The strong reverse correlation between the methylation of the putative control region of the LMP gene and the expression of LMP suggests that methylation has a role in the regulation of this gene.

The strong reaction of T cells against foreign major histocompatibility complex (MHC) antigens, commonly termed "alloreactivity", is not only a nuisance for clinical organ transplantation; it also remains a puzzling question for immunologists. By making use of recent technical developments, alloreactive T cells nominally directed against a mutation in a single MHC class I molecule were found to fall into several major categories. One is recognizing peptides whose occurrence is dependent on one particular MHC allele, another is recognizing peptides supported by several MHC alleles, and a third is recognizing peptides occurring independently of MHC alleles. In a fourth category, the binding to MHC of any of a broad range of peptides appears sufficient. In addition, there are T cells for which no peptide involvement could be detected at all. Even within these categories, the heterogeneity of T cells is considerable: among 16 Kb-reactive T cells analyzed, 15 different modes of reactions were found.

Monosubstituted [4-carboxy-2,6-dinitrophenyl-lysine]cytochromes c were investigated by n.m.r. and e.p.r. Modification of Lys-13 or Lys-72 in ferricytochrome c by 4-chloro-3,5-dinitrobenzoate yields either of two different conformers that are rapidly exchanging in the native form. The equilibrium involves small local changes in the conformation of Met-80 (the sixth ligand) and Phe-82, as a result of whether Lys-13 is the ‘on’ or ‘off’ position in the Lys-13–Glu-90 salt bridge.

Lungs from 191 slaughter pigs with gross lesions indicative of enzootic pneumonia of pigs (EPP) and 80 grossly normal lungs, all originating from 9 different herds, were subjected to microbiological and pathological examinations. The microbiological studies included both bacterial and mycoplasmal culture and also testing for Mycoplasma hyopneumoniaeantigen in tissue by indirect immunofluorescent technique. M. hyopneumoniae, Pasteurella multocidaand Mycoplasma hyorhiniswere detected in 83 %, 43 % and 37 % of the pneumonic lungs, respectively. Mycoplasma floccularewas the most frequently isolated organism in the non-pneumonic lungs. The greatest amounts of macroscopic pneumonia (25.2 %) were recorded in lungs with all the three agents M. hyopneumoniae, P. multocidaand M. hyorhinispresent. The anmounts of pneumonia in lungs with M. hyopneumoniaealone and in concurrence with P. multocida, were 9.3 % and 15.6%, respectively. M. hyorhiniswas also, in this study, associated with higher frequency of diffuse pleuritis. These findings indicate that M. hyorhinismight be involved in the pathogenesis of pneumonia in slaughter pigs. Ninety-six per cent of the isolates of P. multocidafrom pneumonic lungs could be characterized as type A. In the herds which had the most severe pneumonia problems, toxin production was detected in 83 % of the P. multocidastrains while only 28 % were toxigenic in herds with subclinical to moderate pneumonia problems.

The prevalence and pathomorphology of gross lung lesions were studied in 855 slaughter weight pigs from 9 selected herds in south-eastern Norway. Pneumonic or pleuritic lesions were found in 84 % of the lungs, ranging from 37 % in the least affected herd to 97 % in the one most affected. Bronchopneumonia indicative of a primary Mycoplasma hyopneumoniae infection was found in 70 % of the lungs, ranging from 9 % to 82 % in the individual herds. The amount of bronchopneumonic lesions in individual lungs ranged from 0 to 69 %, with an average of 7.8 %. Pleuropneumonia indicative of Actinobacillus (Haemophilus) pleuropneumoniae infection was found in 29 % of the lungs ranging from 0 in the least affected herd to 58 % in the most affected. Diffuse pleuritis was found in 41 % of the lungs and the prevalence ranged from 4 % to 63 %.

The titration curves of solutions of glycine, alanine, α-ammo-butyric acid, leucine, glycyl-glycine, alanyl-glycine, alanyl-alanine, acetone, acetamide, urea, acetic acid, and aceturic acid were determined and some of the relations as dependent upon the chemical structures discussed. The isoelectric points of some of the amphoteric electrolytes were found experimentally. The definition of isoelectric point, its theoretical significance, and method of calculation were considered in some detail.

The saccharogenic enzymes present in potato juice were studied. The actions were followed upon the substances present in the juice and upon added sucrose, maltose, and soluble starch. Sucrase and amylase were found to be present in the juice. No indication of a maltase was obtained. The sucrase showed optimum conditions for action at pH 4 to 5, the amylase at pH 6 to 7, both upon the starch present in the juice and upon added soluble starch. The action of a yeast sucrase preparation upon the juice showed the presence of sucrose (or raffinose) in a concentration of the order of magnitude of 1 per cent.

The ester-hydrolyzing actions of extracts of a number of tissues of rabbits of different ages were studied under comparable conditions. The ages of the rabbits ranged from 8 days before birth to 2162 days. The esters used included phenyl acetate, glyceryl triacetate, methyl butyrate, benzyl acetate, methyl acetate, ethyl acetate, ethyl butyrate, methyl benzoate, ethyl benzoate, and isobutyl acetate. The following tissues were studied: kidney, liver, lung, skin, leg muscle, heart muscle, brain, spleen, stomach, and small intestine. The results, as in previous communications, are presented in the form of plots for the relative enzyme actions, and in tables for the absolute actions. The changes in the curves of the relative actions as the rabbits became older are considered in some detail. The relations between the embryonic state of certain tissues, as shown by their enzyme actions, and the adult state, are described, and compared with their physiological behavior. The probable reversion to a type approaching the embryonic for the oldest rabbits studied is indicated with some of the tissues. The changes in the absolute enzyme actions of the tissues as the rabbits became older are also discussed. The absolute actions do not form as regular a progression as do the relative actions but, at the same time, show marked regularities with increasing age of the rabbits.

The ester-hydrolyzing or lipase actions of extracts of whole rats whose ages ranged from 3 days before birth to 3 years 15 days were tested on ten simple esters by the method described in previous papers. The results are presented in the form of curves, both as absolute actions and as relative actions on the different substrates. The "pictures" of the relative actions changed progressively with increasing age of the rat. For the embryo and the youngest rats, the curves approached those given by the Flexner-Jobling rat carcinoma and by a number of tumors of human origin, changing to a type characteristic of the adult rat, and appearing to revert again to some extent to the embryonic type for the oldest rats. The changes in the actions on individual esters and the relative changes in the actions on different esters are discussed in detail. The greatest increases in actions as the rats became older were found with methyl and ethyl butyrates; at the same time that the actions on some of the other esters were also found to change in characteristic ways. Similar experiments with the protease actions of the extracts of whole rats of different ages on three protein preparations did not give differences similar to those found for the lipase actions. The probable reasons for these observed differences in the two sets of enzyme actions are discussed.

The conditions for the formation of gels from banana extracts were studied. Gels were obtained with extracts more alkaline than pH 7.0 with very small quantities of calcium, strontium, and barium salts, the gel formation with these salts decreasing in the indicated order. In solutions more acid than pH 6.0, no gels were obtained with these salts. Magnesium, lithium, and sodium salts did not cause gel formation either in acid or alkaline solutions. Pancreatine gave a gel on incubation with banana extract at pH 5.0. The gel-forming property of banana extracts was destroyed on boiling.

The ester-hydrolyzing or lipase actions of extracts and whole solids of trout eggs and whole trout of different ages were tested on ten simple esters by the method described in previous papers. Differences in solubility of the enzyme materials of the eggs were found. The "pictures" of the relative enzyme actions changed from a type found with immature eggs to a type which became constant for the fish after they had eaten for 2 weeks. After this, the type did not change up to the age of 4 to 5 years (the oldest trout studied). The absolute ester-hydrolyzing actions of the materials were also presented and discussed.