External and internal glucose mass transfers in succinic acid fermentation with stirred bed of immobilized Actinobacillus succinogenes under substrate and product inhibitions

This paper is dedicated to the study on the external and internal mass transfers of glucose for succinic acid fermentation under substrate and product inhibitions using a bioreactor with stirred bed of immobilized Actinobacillus succinogenes cells. By means of the substrate mass balance for a single particle of biocatalysts, considering the kinetic model adapted for both inhibitory effects, specific mathematical models were developed for describing the profiles of the substrate concentration in the outer and inner regions of biocatalysts and for estimating the substrate mass flows in the liquid boundary layer surrounding the particle and inside the particle. The values of the mass flows were significantly influenced by the internal diffusion velocity and rate of the biochemical reaction of substrate consumption. These cumulated influences led to the appearance of a biological inactive region near the particle center, its magnitude varying from 0 to 5.3% of the overall volume of particles.     

Behavioral, metabolic, and molecular stress responses of marine bivalve Mytilus galloprovincialis during long-term acclimation at increasing ambient temperature

The present study aimed to determine the thermal response of the Mediterranean mussel Mytilus galloprovincialis by integrating information from various levels of biological organization including behavior, metabolic adjustments, heat shock protein expression, and protein kinase activity. Behavioral responses were determined by examining the effect of warming on valve closure and opening. Metabolic impacts were assessed by examining the activity of the key glycolytic enzyme pyruvate kinase (PK). Molecular responses were addressed through the expression of Hsp70 and Hsp90 and the phosphorylation of stress-activated protein kinases, p38 mitogen-activated protein kinase (p38 MAPK) and cJun-N-terminal kinases (JNKs). Mussels increased the duration of valve closure by about sixfold when acclimated to 24 degrees C rather than to 17 degrees C. As indicated by the activity of PK, such behavior caused metabolic depression and probably a shift from aerobic to anaerobic metabolism. Acclimation to temperatures higher than 24 degrees C caused an increase in mortality and induced the expression of Hsp72. Increased phosphorylation of p38 MAPK and JNKs indicated activation of MAPK signaling cascades. The potential involvement of MAPKs in the induction of Hsp genes in the tissues of M. galloprovincialis is discussed. In conclusion, it seems that M. galloprovincialis lives close to its acclimation limits and incipient lethal temperature and that a small degree of warming will elicit stress responses at whole organism and molecular levels.     

Female Genito-genital Rubbing in a Group of Captive Chimpanzees

Wild and captive female bonobos exhibit a form of noncopulatory sexual behavior—genito-genital (GG) rubbing—in which 2 individuals rub their genital regions together. GG-rubbing in bonobos occurs in several contexts and may serve several functions, including tension reduction and reconciliation. It has not been reported for chimpanzees. In a study of captive, adolescent chimpanzees at the New Iberia Research Center, I observed that females rubbed genital regions at rates equivalent to those of bonobos, though the form of the behavior differed in significant ways from classic bonobo GG-rubbing. I describe the pattern of GG-rubbing in the chimpanzees and provide preliminary tests of 5 hypotheses for why the behavior occurs. All 4 females in the study group participated in GG-rubbing, though the frequency with which they initiated and participated varied. Females that GG-rubbed the most also groomed each other the most, supporting the hypothesis that GG-rubbing reinforces or at least reflects social bonds. The data do not support the hypothesis that females GG-rub to reconcile conflicts, to reduce tension during feeding, to signal social status, or to attract mates.     

Rapid stimulation of glucose transport by mitochondrial uncoupling depends in part on cytosolic Ca2+ and cPKC

2,4-Dinitrophenol (DNP) uncouples the mitochondrial oxidativechain from ATP production, preventing oxidative metabolism. Theconsequent increase in energy demand is, however, contested by cellsincreasing glucose uptake to produce ATP via glycolysis. In L6 skeletalmuscle cells, DNP rapidly doubles glucose transport, reminiscent of theeffect of insulin. However, glucose transport stimulation by DNP doesnot require insulin receptor substrate-1 phosphorylation and iswortmannin insensitive. We report here that, unlike insulin, DNP doesnot activate phosphatidylinositol 3-kinase, protein kinaseB/Akt, or p70 S6 kinase. However, chelation of intra- andextracellular Ca²⁺ with1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraaceticacid-AM in conjunction with EGTA inhibited DNP-stimulated glucoseuptake by 78.9 ± 3.5%. BecauseCa²⁺-sensitive, conventionalprotein kinase C (cPKC) can activate glucose transport in L6 musclecells, we examined whether cPKC may be translocated andactivated in response to DNP in L6 myotubes. Acute DNP treatment led totranslocation of cPKCs to plasma membrane. cPKC immunoprecipitated fromplasma membranes exhibited a twofold increase in kinase activity inresponse to DNP. Overnight treatment with 4-phorbol 12-myristate13-acetate downregulated cPKC isoforms , , and  and partiallyinhibited (45.0 ± 3.6%) DNP- but not insulin-stimulatedglucose uptake. Consistent with this, the PKC inhibitorbisindolylmaleimide I blocked PKC enzyme activity at theplasma membrane (100%) and inhibited DNP-stimulated2-[³H]deoxyglucoseuptake (61.2 ± 2.4%) with no effect on the stimulation of glucose transport by insulin. Finally, the selective PKC- inhibitorLY-379196 partially inhibited DNP effects on glucose uptake (66.7 ± 1.6%). The results suggest interfering with mitochondrial ATPproduction acts on a signal transduction pathway independent from thatof insulin and partly mediated byCa²⁺ and cPKCs, of which PKC-likely plays a significant role.

     

AVPR1A Variation in Chimpanzees (Pan troglodytes): Population Differences and Association with Behavioral Style

Primates and other mammals show measurable, heritable variation in behavioral traits such as gregariousness, timidity, and aggression. Connections among behavior, environment, neuroanatomy, and genetics are complex, but small genetic differences can have large effects on behavioral phenotypes. One of the best examples of a single gene with large effects on natural variation in social behavior is AVPR1A, which codes for a receptor of the peptide hormone arginine vasopressin. Work on rodents shows a likely causal association between AVPR1A regulatory polymorphisms and social behavior. Chimpanzees also show variation in the AVPR1A regulatory region, with some individuals lacking a ca. 350-bp segment corresponding to a putative functional element. Thus, chimpanzees have a “short” allele (segment deletion) and a “long” allele (no deletion) at this locus. Here we compare AVPR1A variation in two chimpanzee populations, and we examine behavioral and hormonal data in relation to AVPR1A genotypes. We genotyped AVPR1A in a captive population of western chimpanzees (Pan troglodytes verus, New Iberia Research Center; N = 64) for which we had quantitative measures of personality (based on 15 behavioral style indices, calculated from 3 yr of observational data), dominance rank, and baseline testosterone levels. We also provide the first assessment of AVPR1A genotype frequencies in a wild eastern chimpanzee population (Pan troglodytes schweinfurthii, Ngogo community, Kibale National Park, Uganda; N = 26). Our results indicated that the AVPR1A long allele was associated with a “smart” social personality in captive western chimpanzees, independent of testosterone levels. Although the frequency of the long allele was relatively low in captive western chimpanzees (0.23), it was the major allele in wild eastern chimpanzees (0.62). Our finding that allele and genotype frequencies for the AVPR1A polymorphism differ among chimpanzee populations also highlights the need for comparative studies —across subspecies and research sites— in primate behavioral genetics.     

Normal masticatory function partially protects the rat mandibular bone from estrogen-deficiency induced osteoporosis

Background/aim

In a previous study we showed that mandibular alveolar (trabecular) bone appears to be less sensitive to estrogen deficiency than the proximal tibia spongiosa. We hypothesized that the mechanical loading of the alveolar process during mastication may protect the alveolar bone from the detrimental effects observed in other skeletal sites. To test this hypothesis we compared the effect of ovariectomy on the mandibular alveolar bone and the proximal tibia spongiosa of rats fed either a normal (hard) or a soft diet.

Methods

Forty six-month-old female Sprague–Dawley rats underwent trans-abdominal ovariectomy (OVX) or sham operation (SHAM). Half of the animals received their food in the usual form of pellets (hard consistency), while the other half received a soft, porridge-like, isocaloric diet of identical composition (soft consistency). Micro-computed tomographic histomorphometry was used to evaluate the trabecular micro-architecture. A two-factor analysis of variance was used to test for effects and interaction of ovariectomy and/or soft diet.

Results

OVX had a significantly negative effect on the proximal tibia spongiosa (all parameters under study except trabecular thickness; p<0.001) and on the mandibular alveolar bone (trabecular number and spacing; p<0.05). Soft diet led to a further decrease of mandibular BV/TV (p<0.01), trabecular thickness (p<0.05) and number (p<0.05), as well as increase of separation (p<0.001). A significant interaction was observed between OVX and soft diet concerning the mandibular BV/TV, as well as trabecular thickness and spacing (p<0.05).

Conclusion

Normal (hard) diet limited significantly the negative effects of estrogen deficiency on mandibular alveolar bone micro-architecture four months after ovariectomy.     

Field studies on the relation between the accumulation of heavy metals and metabolic and HSR in the bearded horse mussel Modiolus barbatus

The present study aims to examine whether the seasonal changes in the levels of heavy metals Cd and Pb in the gills of sublittoral mussel Modiolus barbatus from populations distributed in Thermaikos Gulf are correlated to seasonal molecular (Heat Shock Response) and metabolic stress responses of this species. Our results indicate a season effect in the accumulation of heavy metals in the gills of bivalves in the area of Thermaikos Gulf, possibly implicating biological (reproductive cycle), natural (rivers' flow) and anthropogenic factors. Among the members of heat shock proteins (Hsps) examined, inducible Hsp70 seemed to play a major cytoprotective role against toxicity of metals. However, bivalves' tolerance against heavy metals may decrease during warming, arising further questions for their survival in context of global warming.     

The Apolipoprotein E (APOE) Gene Appears Functionally Monomorphic in Chimpanzees (Pan troglodytes)

Background

The human apolipoprotein E (APOE) gene is polymorphic, with three primary alleles (E2, E3, E4) that differ at two key non-synonymous sites. These alleles are functionally different in how they bind to lipoproteins, and this genetic variation is associated with phenotypic variation for several medical traits, including cholesterol levels, cardiovascular health, Alzheimer’s disease risk, and longevity. The relative frequencies of these alleles vary across human populations, and the evolution and maintenance of this diversity is much debated. Previous studies comparing human and chimpanzee APOE sequences found that the chimpanzee sequence is most similar to the human E4 allele, although the resulting chimpanzee protein might function like the protein coded for by the human E3 allele. However, these studies have used sequence data from a single chimpanzee and do not consider whether chimpanzees, like humans, show intra-specific and subspecific variation at this locus.

Methodology and Principal Findings

To examine potential intraspecific variation, we sequenced the APOE gene of 32 chimpanzees. This sample included 20 captive individuals representing the western subspecies (P. troglodytes verus) and 12 wild individuals representing the eastern subspecies (P. t. schweinfurthii). Variation in our resulting sequences was limited to one non-coding, intronic SNP, which showed fixed differences between the two subspecies. We also compared APOE sequences for all available ape genera and fossil hominins. The bonobo APOE protein is identical to that of the chimpanzee, and the Denisovan APOE exhibits all four human-specific, non-synonymous changes and appears functionally similar to the human E4 allele.

Conclusions

We found no coding variation within and between chimpanzee populations, suggesting that the maintenance of functionally diverse APOE polymorphisms is a unique feature of human evolution.