Proteomics and SSH Analyses of ALA-Promoted Fruit Coloration and Evidence for the Involvement of a MADS-Box Gene, MdMADS1

Skin color is a key quality attribute of fruits and how to improve fruit coloration has long been a major concern. 5-Aminolevulinic acid (ALA), a natural plant growth regulator, can significantly increase anthocyanin accumulation in fruit skin and therefore effectively improve coloration of many fruits, including apple. However, the molecular mechanism how ALA stimulates anthocyanin accumulation in fruit skin remains unknown. Here, we investigated the impact of ALA on apple skin at the protein and mRNA levels. A total of 85 differentially expressed proteins in apple skins between ALA and water treatment (control) were identified by complementary gel-based and gel-free separation techniques. Most of these differentially expressed proteins were up-regulated by ALA. Function analysis suggested that 87.06% of the ALA-responsive proteins were associated with fruit ripening. To further screen ALA-responsive regulators, we constructed a subtracted cDNA library (tester: ALA treatment; driver: control) and obtained 104 differentially expressed unigenes, of which 38 unigenes were indicators for the fruit ripening-related genes. The differentially changed proteins and transcripts did not correspond well at an individual level, but showed similar regulated direction in function at the pathway level. Among the identified fruit ripening-related genes, the expression of MdMADS1, a developmental transcription regulator of fruit ripening, was positively correlated with expression of anthocyanin biosynthetic genes (MdCHS, MdDFR, MdLDOX, and MdUFGT) in apple skin under ALA treatment. Moreover, overexpression of MdMADS1 enhanced anthocyanin content in transformed apple calli, which was further enhanced by ALA. The anthocyanin content in MdMADS1-silenced calli was less than that in the control with ALA treatment, but higher than that without ALA treatment. These results indicated that MdMADS1 is involved in ALA-induced anthocyanin accumulation. In addition, anthocyanin-related verification in apple calli suggested that the regulation of MdMADS1 on anthocyanin biosynthesis was partially independent of fruit ripening process. Taken together, our findings provide insight into the mechanism how ALA regulates anthocyanin accumulation and add new information on transcriptase regulators of fruit coloration.

Campylobacter jejuni in Musca domestica: An examination of survival and transmission potential in light of the innate immune responses of the house flies

The house fly, Musca domestica, has been implicated as a vector of Campylobacter spp., a major cause of human disease. Little is known whether house flies serve as biological amplifying hosts or mechanical vectors for Campylobacter jejuni. We investigated the period after C. jejuni had been ingested by house flies in which viable C. jejuni colonies could be isolated from whole bodies, the vomitus and the excreta of adult M. domestica and evaluated the activation of innate immune responses of house flies to ingested C. jejuni over time. C. jejuni could be cultured from infected houseflies soon after ingestion but no countable C. jejuni colonies were observed > 24 h postingestion. We detected viable C. jejuni in house fly vomitus and excreta up to 4 h after ingestion, but no viable bacteria were detected ≥ 8 h. Suppression subtractive hybridization identified pathogen-induced gene expression in the intestinal tracts of adult house flies 4-24 h after ingesting C. jejuni. We measured the expression of immune regulatory (thor, JNK, and spheroide) and effector (cecropin, diptericin, attacin, defensing, and lysozyme) genes in C. jejuni-infected and -uninfected house flies using quantitative real time PCR. Some house fly factor, or combination of factors, eliminates C. jejuni within 24 h postingestion. Because C. jejuni is not amplified within the body of the housefly, this insect likely serves as a mechanical vector rather than as a true biological, amplifying vector for C. jejuni, and adds to our understanding of insect-pathogen interactions.

Characteristics and Expression Profile of KRT71 Screened by Suppression Subtractive Hybridization cDNA Library in Curly Fleece Chinese Tan Sheep

As an important commercial trait for sheep, curly fleece has a great economic impact on production costs and efficiency in sheep industry. To identify genes that are important for curly fleece formation in mammals, a suppression subtractive hybridization analysis was performed on the shoulder skin tissues exposed to two different growth stages of Chinese Tan sheep with different phenotypes (curly fleece and noncurling fleece). BLAST analysis identified 67 differentially expressed genes, of which 31 were expressed lower and 36 were expressed higher in lambs than in adult sheep. Differential expressions of seven randomly selected genes were verified using quantitative real-time polymerase chain reaction (qRT-PCR). KRT71 gene was selected for further study due to its high correlation with the curly hair phenotype in various mammal species. Semi-qPCR showed distinctively high expression of KRT71 in skin tissues. Moreover, qPCR result showed a significantly higher expression of KRT71 in curly fleece than noncurling Tan sheep. The luciferase assay and electrophoresis mobility shift assay showed that there were transcription factor binding sites in the promoter region of KRT71 related to the differential expression of KRT71 at the two growth stages of Tan sheep. Online bioinformation tools predicted MFZ1 as a transcriptional factor that regulates the expression of KRT71. These studies on KRT71 gene revealed some mechanisms underlying the relationship between the KRT71 gene and the curly fleece phenotype of Tan sheep.

Probing the Energetic Metabolism of Resting Cysts under Different Conditions from Molecular and Physiological Perspectives in the Harmful Algal Blooms-Forming Dinoflagellate Scrippsiella trochoidea

Energetic metabolism is essential in maintaining the viability of all organisms. Resting cysts play important roles in the ecology of dinoflagellates, particularly for harmful algal blooms (HABs)-causative species. However, the energetic metabolism underlying the germination potency maintenance of resting cysts of dinoflagellate have been extremely scarce in studies from physiological and, particularly, molecular perspectives. Therefore, we used the cosmopolitan Scrippsiella trochoidea as a representative of HABs-forming and cyst-producing dinoflagellates in this work to obtain novel insights into the molecular mechanisms, regulating the energetic metabolism in dinoflagellate resting cysts, under different physical condition. As the starting step, we established a cDNA subtractive library via suppression subtractive hybridization (SSH) technology, from which we screened an incomplete sequence for the β subunit of ATP synthase gene (β-F1-ATPase), a key indicator for the status of cell's energetic metabolism. The full-length cDNA of β-F1-ATPase gene from S.trochoidea (Stβ-F1-ATPase) was then obtained via rapid amplification of cDNA ends (RACE) (Accession: MZ343333). Our real-time qPCR detections, in vegetative cells and resting cysts treated with different physical conditions, revealed that (1) the expression of Stβ-F1-ATPase in resting cysts was generally much lower than that in vegetative cells, and (2) the Stβ-F1-ATPase expressions in the resting cysts under darkness, lowered temperature, and anoxia, and during an extended duration of dormancy, were significantly lower than that in cysts under the condition normally used for culture-maintaining (a 12 h light:12 h dark cycle, 21 °C, aerobic, and newly harvested). Our detections of the viability (via Neutral Red staining) and cellular ATP content of resting cysts, at the conditions corresponding to the abovementioned treatments, showed that both the viability and ATP content decreased rapidly within 12 h and then maintained at low levels within the 4-day experimentation under all the three conditions applied (4 °C, darkness, and anoxia), which are well in accordance with the measurements of the transcription of Stβ-F1-ATPase. These results demonstrated that the energy consumption of resting cysts reaches a low, but somehow stable, level within a short time period and is lower at low temperature, darkness, and anoxia than that at ambient temperature. Our work provides an important basis for explaining that resting cysts survive long-term darkness and low temperature in marine sediments from molecular and physiological levels.

Identification of differentially expressed genes associated with precocious puberty by suppression subtractive hybridization in goat pituitary tissues

The aim of this study was to identify genes related to precocious puberty expressed in the pituitary of goats at different growth stages by suppression subtractive hybridization (SSH). The pituitary glands from Jining Gray (JG) goats (early puberty) and Liaoning Cashmere (LC) goats (late puberty) at 30, 90, and 180 days were used in this study. To identify differentially expressed genes (DEGs) in the pituitary glands, mRNA was extracted from these tissues, and SSH libraries were constructed and divided into the following groups: juvenile group (30-JG vs. 30-LC, API), puberty group (90-JG vs. 180-LC, BPI), and control group (90-JG vs. 90-LC, EPI). A total of 60, 49, and 58 DEGs were annotated by 222 Gene Ontology (GO) terms and 75 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Most of the DEGs were significantly enriched in GO terms related to 'structural constituent of ribosome', 'translation' and 'GTP binding', and numerous DEGs were also significantly enriched in KEGG terms related to the Jak-STAT signaling and oocyte meiosis pathways. Candidate genes associated with precocious puberty and sexual development were screened from the SSH libraries. These genes were analyzed to determine if they were expressed in the pituitary tissues of the goats at different growth stages and to identify genes that may influence the hypothalamic-pituitary-gonadal (HPG) axis. In this study, we found precocious puberty-related genes (such as PRLP0, EIF5A, and YWHAH) that may be interesting from an evolutionary perspective and that could be investigated for use in future goat breeding programs. Our results provide a valuable dataset that will facilitate further research into the reproductive biology of goats.

Efficient Anchoring of Erianthus arundinaceus Chromatin Introgressed into Sugarcane by Specific Molecular Markers

Erianthus arundinaceus is a valuable gene reservoir for sugarcane improvement. However, insufficient molecular markers for high-accuracy identification and tracking of the introgression status of E. arundinaceus chromatin impede sugarcane breeding. Fortunately, suppression subtractive hybridization (SSH) technology provides an excellent opportunity for the development of high-throughput E. arundinaceus-specific molecular markers at a reasonable cost. In this study, we constructed a SSH library of E. arundinaceus. In total, 288 clones of E. arundinaceus-specific repetitive sequences were screened out and their distribution patterns on chromosomes were characterized by fluorescence in situ hybridization (FISH). A subtelomeric repetitive sequence Ea086 and a diffusive repetitive sequence Ea009, plus 45S rDNA-bearing E. arundinaceus chromosome repetitive sequence EaITS were developed as E. arundinaceus-specific molecular markers, namely, Ea086-128, Ea009-257, and EaITS-278, covering all the E. arundinaceus chromosomes for high-accuracy identification of putative progeny. Both Ea086-128 and Ea009-257 were successfully applied to identify the authenticity of F1, BC1, BC2, BC3, and BC4 progeny between sugarcane and E. arundinaceus. In addition, EaITS-278 was a 45S rDNA-bearing E. arundinaceus chromosome-specific molecular marker for rapid tracking of the inherited status of this chromosome in a sugarcane background. Three BC3 progeny had apparently lost the 45S rDNA-bearing E. arundinaceus chromosome. We reported herein a highly effective and reliable SSH-based technology for discovery of high-throughput E. arundinaceus-specific sequences bearing high potential as molecular markers. Given its reliability and savings in time and efforts, the method is also suitable for development of species-specific molecular markers for other important wild relatives to accelerate introgression of wild relatives into sugarcane.