Identification, Pathogenicity, and Genetic Diversity of Fusarium spp. Associated with Maize Sheath Rot in Heilongjiang Province, China.

Maize sheath rot is a prevalent maize disease in China. From 2020 to 2021, symptomatic samples were collected from the main maize-growing regions of Heilongjiang province. To clarify the population and genetic diversity, as well as the virulence of pathogens responsible for maize sheath rot, a total of 132 Fusarium isolates were obtained and used for follow-up studies. Ten Fusarium species were identified based on morphological characteristics, and phylogenetic analysis was conducted using the TEF-1α gene sequences, including F. verticillioides (50.00%), F. subglutinans (18.94%), the Fusarium incarnatum-equiseti species complex (14.39%), F. temperatum (5.30%), F. acuminatum (3.03%), F. solani (2.27%), F. sporotrichioides (2.27%), F. tricinctum (1.52%), F. asiaticum (1.52%), and F. proliferatum (0.76%). All 10 Fusarium species could produce oval-to-annular lesions on maize sheath, and the lesions were grayish yellow to dark brown in the center and surrounded by a dark gray-to-dark brown halo. Of these, F. tricinctum and F. proliferatum showed significantly higher virulence than the other Fusarium species. In addition, haplotype analysis based on the concatenated sequences of the ITS and TEF-1a genes showed that 99 Fusarium isolates which belonged to the Fusarium fujikuroi species complex-consisting of F. verticillioides isolates, F. subglutinans isolates, F. temperatum isolates, and F. proliferatum isolates-could be grouped into 10 haplotypes, including 5 shared haplotypes (Haps 1, 2, 4, 5, and 6) and 5 private haplotypes (Haps 3, 7, 8, 9, and 10). Furthermore, the F. verticillioides clade in the haplotype network was radial with the center of Hap 2, suggesting that population expansion occurred. This research showed that Fusarium species associated with maize sheath rot in Heilongjiang province are more diverse than previously reported, and this is the first time that F. subglutinans, F. temperatum, F. solani, F. sporotrichioides, F. tricinctum, and F. acuminatum have been confirmed as the causal agents of maize sheath rot in Heilongjiang province.

[Methods used for gene manipulation in mammal female germ cells and early embryos].

For sexual reproduction, oocytes are mammalian female germ cells that provide the majority of maternal genetic material for early stage embryo production and development. Early stage embryos begin the process of multicellular organism formation through cell differentiation. Studies on mammalian female germ cells (oocytes) not only reveal its unique physiological characteristics, but also help understand the mechanism involved in cell differentiation of other cell types. However, because it is difficult to culture in vitro, our understanding of the function of oocytes and early stage embryos remains very limited. Gene editing or manipulation is one of the most commonly used method, which is also useful in the field of gametes study. In this review, we summarized the principles, advantages and disadvantages of techniques, which include conditional knockout, RNA interference, Morpholino, Trim-Away and antibody-mediated inhibition of protein function, currently used for gene manipulation in oocytes and early stage embryos. We also discuss the issues the investigators need to consider. Finally, we highlight the future directions for gene manipulation or editing in female germ cells and early stage embryos.

C-phycocyanin improves the developmental potential of cryopreserved human oocytes by minimizing ROS production and cell apoptosis.

PURPOSE: The cryopreservation process damages oocytes and impairs development potential. As a potent antioxidant, C-phycocyanin (PC) regulates reproductive performance. However, its beneficial effects on vitrified human oocytes remain unknown. METHODS: In this study, human GV-stage oocytes obtained from controlled ovarian hyperstimulation (COH) cycles were randomly allocated to three groups: fresh oocyte without freezing (F group), vitrification in medium supplemented with PC (P group), and vitrification in medium without PC as control group (C group). After warming, viable oocytes underwent in vitro maturation. RESULTS: Our results showed that 3 µg/mL PC treatment increased the oocyte maturation rate after cryopreservation. We also found that PC treatment maintains the regular morphological features of oocytes. After PC treatment, confocal fluorescence staining showed a significant increase in the mitochondrial membrane potential of the vitrified oocytes, along with a notable decrease in intracellular reactive oxygen species and the early apoptosis rate. Finally, after in vitro maturation and parthenogenetic activation, vitrified oocytes had a higher potential for cleavage and blastocyst formation after PC treatment. CONCLUSION: Our results suggest that PC improves the developmental potential of cryopreserved human GV-stage oocytes by attenuating oxidative stress and early apoptosis and increasing the mitochondrial membrane potential.

C-Phycocyanin improves the quality of goat oocytes after in vitro maturation and vitrification.

In vitro maturation (IVM) and cryopreservation of goat oocytes are important for establishing a valuable genetic bank for domesticated female animals and improving livestock reproductive efficiency. C-Phycocyanin (PC) is a Spirulina extract with antioxidant, antiinflammatory, and radical scavenging properties. However, whether PC has positive effect on goat oocytes IVM or developmental competence after vitrification is still unknown. In this study, we found that first polar body extrusion (n = 293), cumulus expansion index (n = 269), and parthenogenetic blastocyst formation (n = 281) were facilitated by adding 30 µg/mL PC to the oocyte maturation medium when compared with the control groups and that supplemented with 3, 10, 100 or 300 µg/mL PC (P < 0.05). Although PC supplementation did not affect spindle formation or chromosome alignment (n = 115), it facilitated or improved cortical granules migration (n = 46, P < 0.05), mitochondria distribution (n = 39, P < 0.05), and mitochondrial membrane potential (n = 46, P < 10-4). Meanwhile, supplementation with 30 µg/mL PC in the maturation medium could significantly inhibit the reactive oxygen species accumulation (n = 65, P < 10-4), and cell apoptosis (n = 42, P < 0.05). In addition, PC increased the oocyte mRNA levels of GPX4 (P < 0.01), and decreased the mRNA and protein levels of BAX (P < 0.01). Next, we investigated the effect of PC supplementation in the vitrification solution on oocyte cryopreservation. When compared with the those equilibrate in the vitrification solution without PC, recovered oocytes in the 30 µg/mL PC group showed higher ratios of normal morphology (n = 85, P < 0.05), survival (n = 85, P < 0.05), first polar body extrusion (n = 62, P < 0.05), and parthenogenetic blastocyst formation (n = 107, P < 0.05). Meanwhile, PC supplementation of the vitrification solution increased oocyte mitochondrial membrane potential (n = 53, P < 0.05), decreased the reactive oxygen species accumulation (n = 73, P < 0.05), promoted mitochondria distribution (n = 58, P < 0.05), and inhibited apoptosis (n = 46, P < 10-3). Collectively, our findings suggest that PC improves goat oocyte IVM and vitrification by reducing oxidative stress and early apoptosis, which providing a novel strategy for livestock gamete preservation and utilization.

mRNA 3' -UTR-mediate translational control through PAS and CPE in sheep oocyte.

In oocytes, the cytoplasmic polyadenylation and maternal mRNAs translation is regulated by cis-elements, including polyadenylation signal (PAS) and cytoplasmic polyadenylation element (CPE) in 3'-UTR. Recent studies illustrate non-canonical polyadenylation mechanisms of translational regulation in mouse oocytes, which is different from that in Xenopus oocytes. However, it is still unclear if this regulation in rodent oocytes functions in the domestic animal oocyte. Here, by using sheep as an animal model, we cloned the 3'-UTRs of Cpeb1 or Btg4 and ligated it into the pRK5-Flag-Gfp vector. Variant numbers and positions of PASs and CPEs within the 3'-UTRs were constructed to detect their effects on translational control. After in vitro-transcription and microinjection into sheep fully grown germinal vesicle stage oocytes, the expression efficiency of mRNAs was detected by the GFP and flag expression. Our results show that: (i) PAS located at the proximal end of 3'-UTR can mediate the translation of the maternal mRNAs, as long as they locate far from CPEs; (ii) The proximal PAS has higher efficiency in regulating transcription than the distal one; (iii) increase of PAS number can promote the translational activity more efficiently; (iv) a single CPE located close to PAS (<50 bp) in 3'-UTRs of Cpeb1 or Btg4 could partially repress translation. In 3'-UTRs of Btg4, two CPEs have a higher inhibitory effect, and three CPEs can completely inhibit mRNA translation. These results confirm the existence of the non-canonical mechanism in domestic animal oocytes.