Improvement in Ovarian Tissue Quality with Supplementation of Antifreeze Protein during Warming of Vitrified Mouse Ovarian Tissue

Ice easily recrystallizes during warming after vitrification, and antifreeze protein (AFP) can inhibit the re-crystallization. However, no study has evaluated the effect of AFP treatment only thereon during warming. This study sought to compare AFP treatment protocols: a conventional protocol with AFP treatment during vitrification and first-step warming and a new protocol with AFP treatment during the first-step warming only. According to the protocols, 10 mg/mL of LeIBP (a type of AFP) was used. Five-week-old B6D2F1 mouse ovaries were randomly divided into a vitrified-warmed control and two experimental groups, one treated with the conventional AFP treatment protocol (LeIBP-all) and the other with the new AFP treatment protocol (LeIBP-w). For evaluation, ratios of ovarian follicle integrity, apoptosis, and DNA double-strand (DDS) damage/repairing were analyzed. The LeIBP-treated groups showed significantly higher intact follicle ratios than the control, and the results were similar between the LeIBP-treated groups. Apoptotic follicle ratios were significantly lower in both LeIBP-treated groups than the control, and the results were not significantly different between the LeIBP-treated groups. With regard to DDS damage/repairing follicle ratio, significantly lower ratios were recorded in both LeIBP-treated groups, compared to the control, and the results were similar between the LeIBP-treated groups. This study demonstrated that both protocols with LeIBP had a beneficial effect on maintaining follicle integrity and preventing follicle apoptosis and DDS damage. Moreover, the new protocol showed similar results to the conventional protocol. This new protocol could optimize the mouse ovary vitrification-warming procedure using AFP, while minimizing the treatment steps.

Effects of supplementation with antifreeze proteins on the follicular integrity of vitrified-warmed mouse ovaries: Comparison of two types of antifreeze proteins alone and in combination / 대한생식의학회지

OBJECTIVE: The aim of this study was to analyze the effect of supplementing vitrification and warming solutions with two types of antifreeze proteins (AFPs) and the combination thereof on the follicular integrity of vitrified-warmed mouse ovaries. METHODS: Ovaries (n=154) were obtained from 5-week-old BDF1 female mice (n=77) and vitrified using ethylene glycol and dimethyl sulfoxide with the supplementation of 10 mg/mL of Flavobacterium frigoris ice-binding protein (FfIBP), 10 mg/mL of type III AFP, or the combination thereof. Ovarian sections were examined by light microscopy after hematoxylin and eosin staining, and follicular intactness was assessed as a whole and according to the type of follicle. Apoptosis within the follicles as a whole was detected by a terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling assay. RESULTS: The proportion of overall intact follicles was significantly higher in the type III AFP-supplemented group (60.5%) and the combination group (62.9%) than in the non-supplemented controls (43.8%, p<0.05 for each). The proportion of intact primordial follicles was significantly higher in the FfIBP-supplemented (90.0%), type III AFP-supplemented (92.3%), and combination (89.7%) groups than in the non-supplemented control group (46.2%, p<0.05 for each). The proportions of non-apoptotic follicles were similar across the four groups. CONCLUSION: Supplementation of the vitrification and warming solutions with FfIBP, type III AFP, or the combination thereof was equally beneficial for the preservation of primordial follicles in vitrified mouse ovaries.

Yeast expression and application of an antifreeze protein from the desert beetle Microdera punctipennis / 生物工程学报

Insect antifreeze protein (AFP) has high antifreeze activity. Antifreeze proteins can be used in cryopreservation of biological tissues and cells. We expressed an antifreeze protein from the desert beetle Microdera punctipennis in yeast and determined the function of the protein at low temperatures. Yeast expression vector, pPIC9K-Mpafp698, was constructed and transformed into Pichia pastoris GS115. The expression of MpAFP698 was induced by methanol, and identified by tricine SDS-PAGE and Western blotting. Mpafp698 gene was inserted into the genome of the host yeast strain GS115, and correctly expressed. Hardly any yeast's own protein was secreted into the media. Cryoprotective experiments showed that MpAFP698 can significantly protect mouse liver as well as other mouse organs from cold damage compared with those in the control of Bovine serum albumin (BSA) addition. Besides, the hemolysis of blood cells protected by MpAFP698 at 4 degrees C was reduced and the survival rate of SF9 cells protected by MpAFP698 after freezing and thawing was increased compared to those of the control with BSA addition. Our results showed that MpAFP698 can be expressed in yeast, which allows a convenient purification of the MpAFP protein that has the cryoprotective effect.

Effect of Antifreeze Protein on Mouse Ovarian Tissue Cryopreservation and Transplantation

PURPOSE: To investigate the effect of antifreeze protein (AFP) supplementation on ovarian vitrification and transplantation. MATERIALS AND METHODS: In this experimental study, we researched a total of 182 ovaries from 4-week-old ICR mice. The equilibration solution included 20% ethylene glycol (EG), and the vitrification solution included 40% EG, 18% Ficoll, and 0.3 M sucrose. Intact ovaries were first suspended in 1 mL of equilibration solution for 10 min, and then mixed with 0.5 mL of vitrification solution for 5 min. Ovaries were randomly assigned to 3 groups and 0, 5, or 20 mg/mL of type III AFP was added into the vitrification solution (control, AFP5, and AFP20 groups, respectively). The vitrified ovaries were evaluated after warming and 2 weeks after autotransplantation. The main outcome measurements are follicular morphology and apoptosis assessed by histology and the TUNEL assay. RESULTS: A significantly higher intact follicle ratio was shown in the AFP treated groups (control, 28.9%; AFP5, 42.3%; and AFP20, 44.7%). The rate of apoptotic follicles was significantly lower in the AFP treated groups (control, 26.6%; AFP5, 18.7%; and AFP20, 12.6%). After transplantation of the vitrified-warmed ovaries, a significantly higher intact follicle ratio was shown in the AFP20 group. The rate of apoptotic follicles was similar among the groups. CONCLUSION: The results of the present study suggest that supplementing AFP in the vitrification solution has beneficial effects on the survival of ovarian tissue during cryopreservation and transplantation.

Protein electrophoretic patterns and antifreezing activity in the leaf apoplast in the tropical andean species Senecio niveoaureus

Tropical high mountain plants have different adaptations to survive extreme daily temperature fluctuations and specially freezing night conditions. In winter plant species, survival to low temperatures is related to the ability of the cell to produce specific low molecular weight proteins (antifreezing proteins) and to export them to the apoplast. In order to see if high mountain tropical plants survive to low temperatures through the same mechanism we collected, during a 24 hourperiod, leaves from Senecio niveoaureus growing at 3,300 and 3,600 m.o.s.l, in the Páramo de Palacio, Chingaza, Colombia. Leaf apoplast proteins had MW between 3512 kDa. Electrophoretic patterns were different depending on the altitude and the time of sampling. However the observed variations could not be linked to changes in temperature or to the altitudinal gradient. Antifreeze activity was detected in leaf apoplast of plants at different altitudes. This is the first report of antifreeze activity in a high mountain tropical species.

Mechanism of bacterial adaptation to low temperature.

Survival of bacteria at low temperatures provokes scientific interest because of several reasons. Investigations in this area promise insight into one of the mysteries of life science - namely, how the machinery of life operates at extreme environments. Knowledge obtained from these studies is likely to be useful in controlling pathogenic bacteria, which survive and thrive in cold-stored food materials. The outcome of these studies may also help us to explore the possibilities of existence of life in distant frozen planets and their satellites.