Project description:Experimental evolution is a powerful approach to study how ecological forces shape microbial genotypes and phenotypes, but to date strains were predominantly adapted to conditions specific to laboratory environments. The lactic acid bacterium Lactococcus lactis naturally occurs on plants and in the dairy environment and it is generally believed, that dairy strains originate from the plant niche. Here we investigated the adaptive process from the plant to the dairy niche and show that during the experimental evolution of a L. lactis plant isolate in milk, several mutations are selected that affect amino acid metabolism and transport. Three independently evolved strains were characterized by whole genome re-sequencing, revealing 4 to 28 mutational changes in the individual strains. Two of the adapted strains showed clearly increased acidification rates and yields in milk, and contained three identical point mutations. Transcriptome profiling and extensive phenotyping of the wild-type plant isolate compared to the evolved mutants, and a "natural" dairy isolate confirmed that major physiological changes associated with improved performance in the dairy environment relate to nitrogen metabolism. The deletion of a putative transposable element led to a significant decrease of the mutation rate in two of the adapted strains. These results specify the adaptation of a L. lactis strain isolated from mung bean sprouts to growth in milk and they demonstrate that niche-specific adaptations found in environmental microbes can be reproduced by experimental evolution. Multiple loop design with 12 samples and 16 dual label arrays. Each sample is hybrdized at least on two different arrays and with both dyes.
Project description:The ability to produce diacetyl from pyruvate and l-serine was studied in various strains of Pediococcus pentosaceus and Pediococcus acidilactici isolated from cheese. After being incubated on both substrates, only P. pentosaceus produced significant amounts of diacetyl. This property correlated with measurable serine dehydratase activity in cell extracts. A gene encoding the serine dehydratase (dsdA) was identified in P. pentosaceus, and strains that showed no serine dehydratase activity carried mutations that rendered the gene product inactive. A functional dsdA was cloned from P. pentosaceus FAM19132 and expressed in Escherichia coli. The purified recombinant enzyme catalyzed the formation of pyruvate from L- and D-serine and was active at low pH and elevated NaCl concentrations, environmental conditions usually present in cheese. Analysis of the amino acid profiles of culture supernatants from dsdA wild-type and dsdA mutant strains of P. pentosaceus did not show differences in serine levels. In contrast, P. acidilactici degraded serine. Moreover, this species also catabolized threonine and produced alanine and α-aminobutyrate.
Project description:Experimental evolution is a powerful approach to study how ecological forces shape microbial genotypes and phenotypes, but to date strains were predominantly adapted to conditions specific to laboratory environments. The lactic acid bacterium Lactococcus lactis naturally occurs on plants and in the dairy environment and it is generally believed, that dairy strains originate from the plant niche. Here we investigated the adaptive process from the plant to the dairy niche and show that during the experimental evolution of a L. lactis plant isolate in milk, several mutations are selected that affect amino acid metabolism and transport. Three independently evolved strains were characterized by whole genome re-sequencing, revealing 4 to 28 mutational changes in the individual strains. Two of the adapted strains showed clearly increased acidification rates and yields in milk, and contained three identical point mutations. Transcriptome profiling and extensive phenotyping of the wild-type plant isolate compared to the evolved mutants, and a "natural" dairy isolate confirmed that major physiological changes associated with improved performance in the dairy environment relate to nitrogen metabolism. The deletion of a putative transposable element led to a significant decrease of the mutation rate in two of the adapted strains. These results specify the adaptation of a L. lactis strain isolated from mung bean sprouts to growth in milk and they demonstrate that niche-specific adaptations found in environmental microbes can be reproduced by experimental evolution.
Project description:In both beef and dairy cattle, the majority of embryo loss occurs in the first 14 days following insemination. During this period, the embryo is completely dependent on its maternal uterine environment for development, growth and ultimately survival, therefore an optimum uterine environment is critical to embryo survival. We used microarrays to assess endometrial gene expression in high and low fertility heifers during the mid-luteal phase of the estrous cycle.
Project description:In both beef and dairy cattle, the majority of embryo loss occurs in the first 14-16 days following insemination. During this period, the embryo is completely dependent on its maternal uterine environment for development, growth and ultimately survival, therefore an optimum uterine environment is critical to embryo survival. We used microarrays to assess endometrial gene expression in high and low fertility heifers during the late-luteal phase of the estrous cycle.
Project description:Over the past three decades, there has been a significant decline in dairy cattle fertility. A large proportion of pregnancy losses are believed to occur during the pre-implantation period, when the developing embryo is elongating rapidly and signaling its presence to the maternal system. The molecular mechanisms that prevent progression of the estrous cycle and allow the allogenic embryo to survive within the maternal environment are not well understood. To gain a more complete picture of these molecular events, global transcriptional profiling was performed using endometrial tissues from reproductive day 17 pregnant and non-pregnant (cycling) Holstein-Friesian dairy cattle.
Project description:The mammary gland redeveloped to the pre-pregnancy state during involution, which shows that the mammary cells have the characteristics of remodeling. The rapidity and degree of mammary gland involution are different between mice and dairy livestock (dairy cows and dairy goats). However, the molecular genetic mechanism of miRNA in involution and remodeling of goat mammary gland has not yet been clarified. Therefore, this study carried out the RNA-sequencing of nonlactating mammary gland tissue of dairy goats in order to reveal the transcriptome characteristics of miRNA in nonlactating mammary tissues and clarify the molecular genetic mechanism of miRNA in mammary cell involution and remodeling.