Diversity and Evolution of the Marsupial Mandibular Angular Process

A medial inflection of the mandibular angular process is present in most marsupials. The few living marsupials that lack this trait either are very specialized forms (e.g., Tarsipes) or show a medial inflection at some point in development that is lost in later ontogenetic stages (cf. Dactylopsila and Phascolarctos). A medially inflected angular process is not present in any known extant or extinct placental (including all Cretaceous taxa that preserve the back of the dentary bone). Some extant placentals with enlarged auditory bullae evolved a medial flange of the angular process as a strategy to increase gape, but this is not homologous to the marsupial condition. We conclude that the medially inflected angular process is a shared derived trait of extant and extinct marsupials. The significant diversity in the form of the medially inflected mandibular angular process in marsupials, documented here for 53 taxa, shows a general relation to dietary adaptations. Herbivores (with well-developed masseter and medial pterygoid muscles) tend to have a shelf-like angular process, while small, insectivorous marsupials generally have a rod-like angular process. A close connection between the angular process and the ectotympanic is maintained during early postnatal development in all marsupials examined, a relation not seen in the placentals examined. A previous hypothesis suggested that the angular process plays a role in hearing in pouch-young Monodelphis. Data on the maturation of the auditory system does not support this hypothesis. Currently there are no data on differences in muscular anatomy or mastication between marsupials and placentals that could serve as a causal explanation for the difference in adult form of the angular process between the two groups.     

The cellular mechanism of circadian rhythms--a view on evidence, hypotheses and problems

A stable period length is a characteristic property of circadian oscillations. The question about whether higher frequency oscillators (0.5-8 hr) contribute to or establish the stable circadian periodicity cannot be answered at present. A sequential coupling of quantal subcycles appears possible on the basis of known "ultradian" oscillations. There is, however, no supporting evidence for such a concept. Phase response curves of the circadian clock derived from various perturbing pulses allow qualitative conclusions concerning the perturbed clock process. Deductions from computer simulations also allow conclusions about the phase of this oscillatory process. The distinction between processes (a) essential to the clock mechanism, (b) maintaining and controlling the clock (inputs) and (c) depending on the clock (outputs) on the basis of "oscillatory" and "change of psi or tau after perturbation" seems to be useful but not stringent. Protein synthesis may be an essential or input process. Oscillatory changes of this process may be due to periodic translational control or RNA-supply. Circadian changes in protein concentration and/or activity may depend on periodic synthesis, proteolysis, covalent modifications or aggregations. Specific essential proteins have not been identified conclusively. The large overlap between the group of agents and treatments that phase shift the clock and the group that induces stress proteins suggest that the latter may play a role in the controlling (input) or essential domain. The role of membranes in the clock mechanism is not clear: concepts assuming an essential function are based on circumstantial evidence. The membrane potential as well as Ca2+ may be involved in either input or essential function. Ca(2+)-calmodulin may also be important as concluded from inhibitor experiments. It is tempting to assume that a calmodulin-dependent kinase is part of a periodic protein phosphorylation process, yet it is not clear whether the periodic protein phosphorylation that has been observed is essential or is just another output process.     

Minimization of excess sludge production by in-situ activated sludge treatment processes — A comprehensive review

The widespread application of conventional activated sludge treatment process has been employed to deal with a variety of municipal and industrial sewage. While the generation of waste activated sludge (WAS) was considerably huge, the management and disposal expenses were substantially costly. A promising process aimed for WAS reduction during the operation process is urgently needed. Thus, increasing attentions emphasizing on the improved or novel sludge reduction processes should be intensively recommended in the future. This review presents the current and emerging technologies for excess sludge minimization within the process of sewage treatment. The ultimate purpose of this paper is to guide or inspire researchers who are seeking feasible and promising technologies (or processes) to tackle the severe WAS problem.     

Expanded bed adsorption in the purification of monoclonal antibodies: a comparison of process alternatives

Expanded bed adsorption (EBA) was examined as the initial capture/purification step in the purification of monoclonal antibodies from Chinese hamster ovary (CHO) cultures. Two process alternatives each using EBA were compared to a conventional Protein A process without EBA. One alternative used Protein A affinity EBA followed by packed-bed cation and anion-exchange steps. The other alternative used cation-exchange EBA as the capture step followed by packed-bed Protein A and anion-exchange steps. The process using Protein A EBA produced comparable purity (host cell protein, DNA, Protein A, antibody aggregate) to the conventional process. However, the Protein A EBA column showed a significant decrease in dynamic capacity with a limited number of cycles. The process using cation EBA achieved comparable levels of host cell proteins (HCP) and DNA but not antibody aggregate or leached Protein A compared to the conventional process.     

Chain termini cross-talk in the swapping process of bovine pancreatic ribonuclease

3D domain swapping is the process by which two or more protein molecules exchange part of their structure to form intertwined dimers or higher oligomers. Bovine pancreatic ribonuclease (RNase A) is able to swap the N-terminal α-helix (residues 1-13) and/or the C-terminal β-strand (residues 116-124), thus forming a variety of oligomers, including two different dimers. Cis-trans isomerization of the Asn113-Pro114 peptide group was observed when the protein formed the C-terminal swapped dimer. To study the effect of the substitution of Pro114 on the swapping process of RNase A, we have prepared and characterized the P114A monomeric and dimeric variants of the enzyme. In contrast with previous reports, the crystal structure and NMR data on the monomer reveals a mixed cis-trans conformation for the Asn113-Ala114 peptide group, whereas the X-ray structure of the C-terminal swapped dimer of the variant is very close to that of the corresponding dimer of RNase A. The mutation at the C-terminus affects the capability of the N-terminal α-helix to swap and the stability of both dimeric forms. The present results underscore the importance of the hydration shell in determining the cross-talk between the chain termini in the swapping process of RNase A.     

Logistic population growth under random dispersal

Various diffusion processes employed for modelling logistic growth are briefly summarized. A discrete-time, discrete-state space stochastic process for population growth is proposed and analyzed with either Bose-Einstein or Maxwell-Boltzmann statistics for the distribution of offspring in available sites in a restricted region. A diffusion approximation is constructed, which differs from those previously employed. The logistic law is a natural deterministic analog of the diffusion process.     

Fermentation database mining by pattern recognition

A large volume of data is routinely collected during the course of typical fermentation and other processes. Such data provide the required basis for process documentation and occasionally are also used for process analysis and improvement. The information density of these data is often low, and automatic condensing, analysis, and interpretation ("database mining") are highly desirable. In this article we present a methodology whereby process variables are processed to create a database of derivative process quantities representative of the global patterns, intermediate trends, and local characteristics of the process. A powerful search algorithm subsequently attempts to extract the specific process variables and their particular attributes that uniquely characterize a class of process outcomes such as high- or low-yield fermentations.The basic components of our pattern recognition methodology are described along with applications to the analysis of two sets of data from industrial fermentations. Results indicate that truly discriminating variables do exist in typical fermentation data and they can be useful in identifying the causes or symptoms of different process outcomes. The methodology has been implemented in a user-friendly software, named db-miner, which facilitates the application of the methodology for efficient and speedy analysis of fermentation process data. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 443-452, 1997.     

The A-minor motifs in the decoding recognition process

The formation of A-minor motifs, mediated by adenines binding into the shallow/minor groove of stacked and helical Watson-Crick base pairs, is described. The conformations of the bacterial ribosomal decoding A site in various crystal structures are reviewed. The adenines A1492 and A1493 of the A site are seen either tucked in within the internal loop or bulging out and poised for interaction. This dynamic equilibrium contributes to the decoding process of the codon:anticodon base pairings. Aminoglycoside antibiotics lock the conformation of the A site in a single state with bulged-out adenines and thereby disrupt regulation of the decoding process.     

The Cellular Mechanism of Orcadian Rhythms–A View on Evidence,Hypotheses and Problems

A stable period length is a characteristic property of circadian oscillations. The question about whether higher frequency oscillators (0.5–8 hr) contribute to or establish the stable circadian periodicity cannot be answered at present. A sequential coupling of quantal subcycles appears possible on the basis of known “ultradian” oscillations. There is, however, no supporting evidence for such a concept. Phase response curves of the circadian clock derived from various perturbing pulses allow qualitative conclusions concerning the perturbed clock process. Deductions from computer simulations also allow conclusions about the phase of this oscillatory process.

The distinction between processes (a) essential to the clock mechanism, (b) maintaining and controlling the clock (inputs) and (c) depending on the clock (outputs) on the basis of “oscillatory” and “change of ? or τ after perturbation” seems to be useful but not stringent. Protein synthesis may be an essential or input process. Oscillatory changes of this process may be due to periodic translational control or RNA-supply. Circadian changes in protein concentration and/or activity may depend on periodic synthesis, proteolysis, covalent modifications or aggregations. Specific essential proteins have not been identified conclusively. The large overlap between the group of agents and treatments that phase shift the clock and the group that induces stress proteins suggest that the latter may play a role in the controlling (input) or essential domain.

The role of membranes in the clock mechanism is not clear: concepts assuming an essential function are based on circumstantial evidence. The membrane potential as well as Ca²⁺ may be involved in either input or essential function. Ca²⁺ -calmodulin may also be important as concluded from inhibitor experiments. It is tempting to assume that a calmodulin-dependent kinase is part of a periodic protein phosphorylation process, yet it is not clear whether the periodic protein phosphorylation that has been observed is essential or is just another output process.     

Bayesian nonparametric inference for panel count data with an informative observation process

In this paper, the panel count data analysis for recurrent events is considered. Such analysis is useful for studying tumor or infection recurrences in both clinical trial and observational studies. A bivariate Gaussian Cox process model is proposed to jointly model the observation process and the recurrent event process. Bayesian nonparametric inference is proposed for simultaneously estimating regression parameters, bivariate frailty effects, and baseline intensity functions. Inference is done through Markov chain Monte Carlo, with fully developed computational techniques. Predictive inference is also discussed under the Bayesian setting. The proposed method is shown to be efficient via simulation studies. A clinical trial dataset on skin cancer patients is analyzed to illustrate the proposed approach.     

Ancestral processes in population genetics-the coalescent

A special stochastic process, called the coalescent, is of fundamental interest in population genetics. For a large class of population models this process is the appropriate tool to analyse the ancestral structure of a sample of n individuals or genes, if the total number of individuals in the population is sufficiently large. A corresponding convergence theorem was first proved by Kingman in 1982 for the Wright-Fisher model and the Moran model. Generalizations to a large class of exchangeable population models and to models with overlying mutation processes followed shortly later. One speaks of the "robustness of the coalescent, as this process appears in many models as the total population size tends to infinity. This publication can be considered as an introduction to the theory of the coalescent as well as a review of the most important "convergence-to-the-coalescent-theorems. Convergence theorems are not only presented for the classical exchangeable haploid case but also for larger classes of population models, for example for diploid, two-sex or non-exchangeable models. A review-like summary of further examples and applications of convergence to the coalescent is given including the most important biological forces like mutation, recombination and selection. The general coalescent process allows for simultaneous multiple mergers of ancestral lines.     

Evaluation of protein engineering and process optimization approaches to enhance antibody drug manufacturability

A potent single digit picomolar fully human monoclonal antibody (hMAb) inhibitor with a high degree of specificity to the antigen of interest was identified from a phage display library. The hMAb, however, exhibited a high degree of hydrophobicity and easily formed insoluble aggregates when purified using a Protein A based generic process. Strategies were designed using both protein engineering and process development approaches to optimize the molecule's amino acid sequence and its behavior in process conditions. The insoluble aggregation issue was brought under control by one single amino acid mutation in CDR region or by switching to non-ProA based purification process. Our study therefore presents the rational manufacturability design for future monoclonal antibody product and its purification process under the quality by design concept by either engineering the drug molecule to adapt existing platform process or optimizing the process to fit the specific properties of the drug product.     

The Cellular Mechanism of Orcadian Rhythms-A View on Evidence, Hypotheses and Problems

A stable period length is a characteristic property of circadian oscillations. The question about whether higher frequency oscillators (0.5-8 hr) contribute to or establish the stable circadian periodicity cannot be answered at present. A sequential coupling of quantal subcycles appears possible on the basis of known “ultradian” oscillations. There is, however, no supporting evidence for such a concept. Phase response curves of the circadian clock derived from various perturbing pulses allow qualitative conclusions concerning the perturbed clock process. Deductions from computer simulations also allow conclusions about the phase of this oscillatory process.

The distinction between processes (a) essential to the clock mechanism, (b) maintaining and controlling the clock (inputs) and (c) depending on the clock (outputs) on the basis of “oscillatory” and “change of φ or τ after perturbation” seems to be useful but not stringent. Protein synthesis may be an essential or input process. Oscillatory changes of this process may be due to periodic translational control or RNA-supply. Circadian changes in protein concentration and/or activity may depend on periodic synthesis, proteolysis, covalent modifications or aggregations. Specific essential proteins have not been identified conclusively. The large overlap between the group of agents and treatments that phase shift the clock and the group that induces stress proteins suggest that the latter may play a role in the controlling (input) or essential domain.

The role of membranes in the clock mechanism is not clear: concepts assuming an essential function are based on circumstantial evidence. The membrane potential as well as Ca²⁺ may be involved in either input or essential function. Ca²⁺ -calmodulin may also be important as concluded from inhibitor experiments. It is tempting to assume that a calmodulin-dependent kinase is part of a periodic protein phosphorylation process, yet it is not clear whether the periodic protein phosphorylation that has been observed is essential or is just another output process.     

Reductive activation of type 2 ribosome-inactivating proteins is promoted by transmembrane thioredoxin-related protein

Members of the type 2 ribosome-inactivating proteins (RIPs) family (e.g. ricin, abrin) are potent cytotoxins showing a strong lethal activity toward eukaryotic cells. Type 2 RIPs contain two polypeptide chains (usually named A, for "activity", and B, for "binding") linked by a disulfide bond. The intoxication of the cell is a consequence of a reductive process in which the toxic domain is cleaved from the binding domain by oxidoreductases located in the lumen of the endoplasmic reticulum (ER). The best known example of type 2 RIPs is ricin. Protein disulfide isomerase (PDI) was demonstrated to be involved in the process of ricin reduction; however, when PDI is depleted from cell fraction preparations ricin reduction can still take place, indicating that also other oxidoreductases might be implicated in this process. We have investigated the role of TMX, a transmembrane thioredoxin-related protein member of the PDI family, in the cell intoxication operated by type 2 RIPs ricin and abrin. Overexpressing TMX in A549 cells resulted in a dramatic increase of ricin or abrin cytotoxicity compared with control mock-treated cells. Conversely, no difference in cytotoxicity was observed after treatment of A549 cells or control cells with saporin or Pseudomonas exotoxin A whose intracellular mechanism of activation is not dependent upon reduction (saporin) or only partially dependent upon it (Pseudomonas exotoxin A). Moreover, the silencing of TMX in the prostatic cell line DU145 reduced the sensitivity of the cells to ricin intoxication further confirming a role for this enzyme in intracellular ricin activation.     

On the stochastic interpretation of a pathological cell renewal system,I: Theoretical basis

The population constituted by parenchymal liver cells is normally a static or slowly expanding one. This is in contrast with “renewal systems,” or cell populations which turn over more or less rapidly. In experimental situations tending to produce cirrhosis of the liver the rate of cell renewal is appreciable. The situation then corresponds to the definition of a “renewal system.” A repeating unit of the liver lattice structure is proposed in which liver cells are assumed to be sequestrated by anatomical constraints on cell migration, and the order of magnitude of its population determined. The characteristics of the simple birth-and-death process are reviewed to show how it leads to greater fluctuation than does a pure birth process with equivalent expected net growth. A hypothetical birth-and-death process is proposed for the renewal of the cell population of the liver unit. The rate of cell proliferation is placed at a level comparable to that found in reports of experimental cirrhosis taken from the literature. This example of a birth-and-death process leads to the prediction of appreciable fluctuation in the population of the liver unit. It is suggested that fluctuations of this kind may account for some of the morphological features of cirrhosis and lead to a new definition of “nodular regeneration.”     

A possible model for receptors in excitable membranes

A model is proposed for receptors in excitable membranes based on the following assumptions. The receptor site and the process it excites in the membrane are located close to each other. The change of the electrostatic potential in the neighbourhood of the receptor site on the adsorption of a molecule (or ion) influences a potential dependent process in the membrane, such as ion permeability, rate of enzymatic reactions, ion binding etc. A comment is also made about the connection between measured physiological activity of a molecule and its ?real” physical activity.     

Synapsin I phosphorylated by Ca2+, calmodulin-dependent protein kinase II is able to self-degrade.

Phosphorylation of the neurospecific protein synapsin I (SI) by various cellular protein kinases was studied. The analysis of functional properties of phosphosynapsins showed that in the case of PK II-mediated modification of the protein, it becomes capable of self-degradation. The latter process was found to be specific and did not appear to be characteristic of the phosphoforms emerging after the protein modification by PK C or PK A. A possible involvement of the process in the regulation of neurotransmitter secretion is discussed.     

A condition for the extinction of a branching process with an absorbing lower barrier

Summary A branching process with an absorbing lower barrier is considered. This is a Galton-Watson process with the condition that at any generation the number of individuals is greater than a lower barrier or it is equal to zero (i.e. all individuals in populations which are too small die and have no offspring). A necessary and sufficient condition is given for the process to become extinct with probability one. At the end of the paper there are three illustrating examples.Now at the Division of Mathematics and Statistics, CSIRO, Canberra, A.C.T. 2601, Australia.     

The role of genome repetitive sequences in primary hypertension

Genetic determining factors of essential hypertension seems to involve a dynamic mutation or a similar process. The mobile elements of the genome: moderately recurrent sequences, play a special role in initiation of such a process. A possible molecular mechanism of the initiation and development of the dynamic mutation, is described.     

猕猴桃优良株系果实生长发育规律研究

猕猴桃果实生长发育过程可分为三个时期。(1)迅速增长期:中华猕猴桃大约从4月中旬至6月上旬;美味猕猴桃大约从4月底或5月初至6月中下旬。(2)缓慢增长期:中华猕猴桃约自6月上旬至7月下旬;美味猕猴桃自6月下旬至7月下旬。(3)停滞增长期:中华猕猴桃从7月下旬至8月底或9月初;美味猕猴桃自8月上旬至9月上中旬。 中华猕猴桃优株果实可溶性固形物含量增长过程可分为四个阶段:(1)微升增长阶段,持续时间5周左右;(2)活跃增长阶段,持续2周左右;(3)迅速增长阶段,持续2周左右;(4)渐缓增长阶段。美味猕猴桃优株及绿果猕猴桃果实固形物含量增大变化的阶段性不明显。