The importance of aeration strategy in fuel alcohol fermentations contaminated with Dekkera/Brettanomyces yeasts

Whole corn mash fermentations infected with industrially-isolated Brettanomyces yeasts were not affected even when viable Brettanomyces yeasts out-numbered Saccharomyces yeasts tenfold at the onset of fermentation. Therefore, aeration, a parameter that is pivotal to the physiology of Dekkera/Brettanomyces yeasts, was investigated in mixed culture fermentations. Results suggest that aeration strategy plays a significant role in Dekkera/Brettanomyces-mediated inhibition of fuel alcohol fermentations. Although growth of Saccharomyces cerevisiae was not impeded, mixed culture fermentations aerated at rates of ≥20 ml air l⁻¹ mash min⁻¹ showed decreased ethanol yields and an accumulation of acetic acid. The importance of aeration was examined further in combination with organic acid(s). Growth of Saccharomyces occurred more rapidly than growth of Brettanomyces yeasts in all conditions. The combination of 0.075% (w/v) acetic acid and contamination with Brettanomyces TK 1404W did not negatively impact the final ethanol yield under fermentative conditions. Aeration, however, did prove to be detrimental to final ethanol yields. With the inclusion of aeration in the control condition (no organic acid stress) and in each fermentation containing organic acid(s), the final ethanol yields were decreased. It was therefore concluded that aeration strategy is the key parameter in regards to the negative effects observed in fuel alcohol fermentations infected with Dekkera/Brettanomyces yeasts.     

Phylogeography of the Qinghai-Tibetan Plateau endemic Juniperus przewalskii (Cupressaceae) inferred from chloroplast DNA sequence variation

The vegetation of the northeast Qinghai-Tibetan Plateau is dominated by alpine meadow and desert-steppe with sparse forests scattered within it. To obtain a better understanding of the phylogeography of one constituent species of the forests in this region, we examined chloroplast trnT-trnF and trnS-trnG sequence variation within Juniperus przewalskii, a key endemic tree species. Sequence data were obtained from 392 trees in 20 populations covering the entire distribution range of the species. Six cpDNA haplotypes were identified. Significant population subdivision was detected (G(ST) = 0.772, N(ST) = 0.834), suggesting low levels of recurrent gene flow among populations and significant phylogeographic structure (N(ST) > G(ST), P < 0.05). Eight of the nine disjunct populations surveyed on the high-elevation northeast plateau were fixed for a single haplotype (A), while the remaining, more westerly population, contained the same haplotype at high frequency together with two low frequency haplotypes (C and F). In contrast, most populations that occurred at lower altitudes at the plateau edge were fixed or nearly fixed for one of two haplotypes, A or E. However, two plateau edge populations had haplotype compositions different from the rest. In one, four haplotypes (A, B, D and E) were present at approximately equivalent frequencies, which might reflect a larger refugium in the area of this population during the last glacial period. Phylogenetic analysis indicated that the most widely distributed haplotype A is not ancestral to other haplotypes. The contrasting phylogeographic structures of the haplotype-rich plateau edge area and the almost haplotype-uniform plateau platform region indicate that the plateau platform was recolonized by J. przewalskii during the most recent postglacial period. This is supported by the findings of a nested clade analysis, which inferred that postglacial range expansion from the plateau edge followed by recent fragmentation is largely responsible for the present-day spatial distribution of cpDNA haplotypes within the species.     

Recent, allopatric, homoploid hybrid speciation: the origin of Senecio squalidus (Asteraceae) in the British Isles from a hybrid zone on Mount Etna, Sicily

Homoploid hybrid speciation occurs through stabilization of a hybrid segregate (or segregates) isolated by premating and/or postmating barriers from parent taxa. Theory predicts that ecological and spatial isolation are of critical importance during homoploid hybrid speciation, and all confirmed homoploid hybrid species are ecologically isolated from their parents. Until recently, such species have been identified long after they originated, and consequently it has not been possible to determine the relative importance of spatial and ecological isolation during their origin. Here we present evidence for the recent origin (within the past 300 years) of a new homoploid hybrid species, Senecio squalidus (Asteraceae), in the British Isles, following long-distance dispersal of hybrid material from a hybrid zone between S. aethnensis and S. chrysanthemifolius on Mount Etna, Sicily, Italy. Historical records show that such hybrid material from Sicily was introduced to the Oxford Botanic Garden in Britain in the early part of the 18th century and that S. squalidus began to spread from there after approximately 90 years. A survey of randomly amplified polymorphic DNA/intersimple sequence repeats (RAPD/ISSR) marker variation demonstrated that S. squalidus is a diploid hybrid derivative of S. aethnensis and S. chrysanthemifolius that grow at high and low altitudes, respectively, on Mount Etna and that form a hybrid zone at intermediate altitudes. Senecio squalidus contained 11 of 13 RAPD/ISSR markers that were recorded at high frequency in S. chrysanthemifolius but were absent or occurred at low frequency in S. aethnensis, and 10 of 13 markers for which the reverse was true. Bayesian admixture analysis showed that all individuals of S. squalidus surveyed were of mixed ancestry with relatively high mean proportions of ancestry derived from both S. chrysanthemifolius and S. aethnensis (0.644 and 0.356, respectively). We argue that long-distance isolation of hybrid material from its parents on Mount Etna would have helped favor the origin and establishment of S. squalidus in the British Isles, regardless of whether the initial hybrid material introduced to Britain was preadapted to local conditions.     

Diminished maternal responsiveness during pregnancy in multiparous female common marmosets

Common marmoset monkeys (Callithrix jacchus) live in small groups in which, usually, only a single female breeds and all group members provide infant care. When two females breed concurrently, however, they may commonly kill one another's infants, especially during the peripartum period. To investigate the mechanisms underlying infanticide by breeding females, we characterized responses of multiparous females to infants and determined circulating hormone levels in adult females during early pregnancy, late pregnancy, and the early postpartum period. Additionally, we compared the responses of postpartum females to their own infants and infants of other females (unfamiliar infants). Postpartum females were highly maternal toward both their own and unfamiliar infants, and showed no differences in their behavioral or hormonal responses to the two. During both early and late pregnancy, however, these females exhibited longer latencies to initially approach unfamiliar infants and spent less time carrying unfamiliar infants. Moreover, females spent less time carrying unfamiliar infants during late pregnancy than early pregnancy. Most late pregnant females never carried infants, and those that did rejected them quickly. Prolactin concentrations were higher and progesterone concentrations lower postpartum than in early or late pregnancy, while estradiol concentrations, the estradiol-to-progesterone ratio, and cortisol levels were higher during late pregnancy. Within reproductive conditions, however, maternal behaviors were not correlated with hormone levels. These results suggest that maternal responsiveness in marmosets may be attenuated during pregnancy, especially late pregnancy, and this may contribute to infanticide by breeding females.     

Reproductive isolation of a new hybrid species, Senecio eboracensis Abbott & Lowe (Asteraceae)

The nature and extent of reproductive isolation was examined between a new self-compatible hybrid species Senecio eboracensis (2n=40) and its parents, self-incompatible S. squalidus (2n=20) and self-compatible S. vulgaris (2n=40). The triploid F(1) of S. eboracensis x S. squalidus exhibited very low seed set (x=0.63%), and F(2) and F(3) progeny were able to recover nominal levels of fertility (x=23.9 and 9.7%), while F(1) and F(2) offspring of S. eboracensis x S. vulgaris showed reduced seed set (x=63.8 and 58.8%). In both cases, evidence from previous work indicates that reduced fertility is associated with meiotic chromosome mispairing, and is a likely consequence of recombining both parental genomes within this new taxon. No hybrid offspring between S. eboracensis and S. squalidus were found in the wild, and only one such hybrid was recorded among 769 progeny produced by S. eboracensis surrounded by S. squalidus on an experimental plot. Natural crossing between S. eboracensis and S. vulgaris was recorded to be very low (between 0 and 1.46%) in the wild, but rose to 18.3% when individuals of S. eboracensis were surrounded by plants of S. vulgaris. It was concluded that strong breeding barriers exist between the new hybrid species and its two parents. Prezygotic isolation between S. eboracensis and S. vulgaris is likely to be largely due to both species reproducing by predominant self-fertilisation. However, differences recorded for germination, seedling survival, time of flowering and characters associated with pollinator attraction, plus significant clumping of juvenile and adult conspecifics in the wild, probably also contribute to reproductive isolation and ecological differentiation.     

T47D breast cancer cell growth is inhibited by expression of VACM-1, a cul-5 gene

Vasopressin-activated calcium-mobilizing (VACM-1), a cul-5 gene, is localized on chromosome 11q22-23 close to the gene for Ataxia Telangiectasia in a region associated with a loss of heterozygosity in breast cancer tumor samples. To examine the biological role of VACM-1, we studied the effect of VACM-1 expression on cellular growth and gene expression in T47D breast cancer cells. Immunocytochemistry studies demonstrated that VACM-1 was expressed in 0.6-6% of the T47D cells and localized to the nucleus of mitotic cells. Overexpressing VACM-1 significantly attenuated cellular proliferation and MAPK phosphorylation when compared to the control cells. In addition, VACM-1 decreased egr-1 and increased Fas-L mRNA levels. Further, egr-1 protein levels were significantly lower in the nuclear fraction from VACM-1 transfected cells when compared to controls. These data indicate that VACM-1 is involved in the regulation of cellular growth.     

Effects of enzymatic digestion on compressive properties of rat intervertebral discs

Enzymatic treatments were applied to rat motion segments to establish structure–function relationships and determine mechanical parameters most sensitive to simulated remodeling and degeneration. Rat caudal and lumbar disc biomechanical behaviors were evaluated to improve knowledge of their similarities and differences due to their frequent use during in vivo models. Caudal motion segments were assigned to four groups: soaked (control), genipin treated, elastase treated, and collagenase treated. Fresh lumbar and caudal discs were also compared. The mechanical protocol involved five force-controlled loading stages: equilibration, cyclic compression-tension, quasi-static compression, frequency sweep, and creep. Crosslinking was found to have the greatest effect on IVD properties at resting stress. Elastin's role was greatest in tension and at higher force conditions, where GAG content was also a contributing factor. Collagenase treatment caused tissue compaction, which impacted mechanical properties at both high and low force conditions. Equilibration creep and cyclic compression-tension tests were the mechanical tests most sensitive to alterations in specific matrix constituents. Caudal and lumbar motion segments had many similarities but biomechanical differences suggested some distinctions in collagenous structure and water transport characteristics in addition to the geometric differences. Results provide a basis for interpreting biomechanical changes observed in animal model studies of degeneration and remodeling, and underscore the need to maintain and/or repair collagen integrity in IVD health and disease.     

Beta7 integrin deficiency suppresses B cell homing and attenuates chronic ileitis in SAMP1/YitFc mice

Lymphocyte recruitment to intestinal tissues depends on β(7) integrins. In this study, we studied disease severity and lymphocyte recruitment into the small intestine in SAMP1/YitFc mice, which develop chronic ileitis with similarity to human Crohn's disease. To assess the role of β(7) integrins in chronic ileitis, we generated SAMP1/YitFc lacking β(7) integrins (SAMP1/YitFc Itgb7(-/-)) using a congenic strain developed via marker-assisted selection. We analyzed ileal inflammation in SAMP1/YitFc and SAMP1/YitFc Itgb7(-/-) mice by histopathology and the distribution of T and B lymphocytes in the mesenteric lymph nodes (MLNs) by flow cytometry. Short-term (18 h) adoptive transfer experiments were used to study the in vivo homing capacity of T and B lymphocytes. In both young (<20 wk) and old (20-50 wk) SAMP1/YitFc Itgb7(-/-) mice, ileitis was reduced by 30-50% compared with SAMP1/YitFc mice. SAMP1/YitFc Itgb7(-/-) mice showed a dramatic 67% reduction in the size of their MLNs, which was caused by a 85% reduction in lymphocyte numbers and reduced short-term B cell homing. Flow cytometric analysis revealed a highly significant decrease in the percentage of B cells in MLNs of SAMP1/YitFc Itgb7(-/-) mice. Cotransfer of SAMP1/YitFc MLN B cells but not SAMP1/YitFc Itgb7(-/-) MLN B cells along with CD4(+) T cells resulted in exacerbated ileitis severity in SCID mice. Our findings suggest that β(7) integrins play an essential role in spontaneous chronic ileitis in vivo by promoting homing of disease-exacerbating B cells to MLNs and other intestinal tissues.