Ugly Cute Mouse In The House by Jesther Chong See Mun https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj B6 nude is an immunodeficient (T-cell deficient) mouse due to the lack of thymus and is furless. These phenotypes occur due to the intentional inactivating mutation of the Foxn1 gene. en-us 2022-03-31 15:36:48 UTC 2022-04-26 08:54:23 UTC hello@padlet.com https://padlet-uploads.storage.googleapis.com/1650327133/a9d27392cf9c572ebe3d6719c8283981/nci_vol_1970_72.jpg Taxonomy JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2127013204 2022-04-03 08:56:38 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2127013204 Strain or Stock? 🤔🤔🤔🤔 JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2127018834 Stocks refer to outbreeding of the laboratory animals while Strains refer to inbreeding of the  laboratory animal.

B6 nude is a strain - More specifically, it is a congenic strain! 

Congenic strains are produced from backcrossing to a parental inbred strain, with selection from the donor strain for at least 10 generations (The Jackson Laboratory, 2021).]]> 2022-04-03 09:06:22 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2127018834 Morphology JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2127021786 Homozygous B6 Nude: 
  • Lack of Thymus
  • Furless 
  • Wrinkled Body
  • Black Colour 
  • Small in Size

Heterozygous B6 Nude:
  • Has a Thymus (Low Thymus Weight)
  • Has Fur
  • Black Colour
  • Small in Size
]]> 2022-04-03 09:11:36 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2127021786 History & Origin JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146534190 Before the usage of nude mice, researchers would have to perform thymectomy procedure to other laboratory mouse models. Nude mice is the main reason why thymectomy procedure has reduced significantly for research.

In 1980, the National Institute of Health Animal Genetic Resource received the B6 Nude Spontaneous mutant model. The mice were backcrossed nine generations (N9). In 2007 an additional backcross was completed to bring to N10.(The Jackson Laboratory, 2022)

B6 Nude originated from C57BL/6. In Taconic Biosciences, B6 Nude was produced from Foxn1nu mutation backcrossed to the C57BL/6 inbred strain for ten generations. (Taconic Biosciences, 2022)

]]> 2022-04-18 03:47:28 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146534190 Uses in Biomedical Research #1 JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146534517 To study human tumor pathogenesis in vivo

Link: http://jorjanijournal.goums.ac.ir/article-1-665-en.pdf 

Cancer stem cells (CSC) are the main reason of the failure of cancer therapy due to cancer relapse and metastasis. In this research by Ayyoob Khosravi and his team, with the title, ' Tumorigenicity of Esophageal Cancer Stem Cells (ECSCs) in nude mouse xenograft model' they aimed to monitor the CSC tumorigenicity using xenograft B6 Nude mouse. They stated that studying CSC in vitro and in vivo produce different results as both give rise to different environment to the CSC which can cause changes in tumorigenicity mechanisms in both cases.  In vivo study will definitely provide an environment as similar as possible to that in human. In this study, B6 Nude mice were injected with YM1 cancer stem-like cells enriched by sphere formation assay. Then, the ability of CSC, isolated with sphere formation assay, to form xenograft tumors in B6 nude mice was monitored. The results showed that the size of tumors was appropriate to the number of cells injected and the minimum cell number required for tumor formation in the study was 4×104 cells. Thus,  YM1 cancer stem-like cells enriched by sphere formation assay were able to make subcutaneous tumors in B6 nude mouse models. This further supporting that nude mouse models are practical method to stimulate and study human cancer in vivo (Ayyoob Khosravi et al, 2019)]]> 2022-04-18 03:47:54 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146534517 Physiology JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146535019 Immune System:
B6 Nude is an immunodeficient (T cell deficient) mouse because it lacks a thymus, whereby maturation of T lymphocytes normally takes place. Without T lymphocytes in this mouse's body, the body immune system is compromised as it cannot detect pathogen or non-self cells in the body. It's cell-mediated immunity is lost. Therefore, this condition makes it suitable for xenograft studies and cancer studies.

Although there are still some B lymphocytes in the B6 nude mouse's body despite having defects in development of B lymphocytes, immune response still requires T lymphocytes to activate B lymphocytes to produce antibodies during the first exposure. So, activation of B lymphocytes still cannot take place.

Reproduction:
B6 nude females follow 4 phases of estrous cycle which are diestrus, proestrus, estrus and metestrus. the estrus and metestus phases are suitable for mating period. However, females are not effective breeders. Ovulation starts late at 2.5 months and ends early at four months. B6 nude female mouse can produce an average of 8 pups in a litter.

Integumentary System:
The mutation (Foxn1nu) results in the B6 nude mouse to have functional but abnormal or faulty hair growth follicles which contributes to the hairless appearance.

Skeletal System:
According to the vertebral formula C7 T13 L6 S4 C28,  B6 nude has 7 cervical vertebrae, 13 thoracic vertebrae, 6 lumbar vertebrae, 4 sacral vertebrae and 28 caudal vertebrae. ]]> 2022-04-18 03:48:39 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146535019 Gender Difference JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146535118 Similar to other types of mouse, looking at the distance between the anus and the genital can differentiate the gender. But, it can be tricky especially in newborns and few days old pups. 

Males have a longer anal-genital distance while females have a shorter anal-genital distance. ]]> 2022-04-18 03:48:49 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146535118 Nomenclature JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146536102 The nomenclature for B6 Nude is B6.Cg/NTac-Foxn1nu NE10.

B6 refers to B6 or Black 6 nude mouse. Cg refers to complex genetics. N refers to the brand. Tac refers to the company, Taconic Biosciences. Foxn1 refers to targeted gene mutation. nu which means nude, refers to the allele. 

NE refers to N equivalent whereby it is expressed in cases of complex mating systems. Thus, NE10 refers to backcrossing for 10 generations. It does not involve brother x sister mating (The Jackson Laboratory, 2022).]]> 2022-04-18 03:50:07 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2146536102 What does BACKCROSSING mean? JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2147097640 Backcrossing is the crossing of a hybrid with one of its parent or an adult genetically similar to the parent to produce offspring that are almost genetically identical to the parent. 

The purpose of backcrossing is to obtain a line as identical as possible to the recurrent parent with the addition of the gene of interest that has been added through breeding (The Jackson Laboratory, 2022).]]> 2022-04-18 15:06:19 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2147097640 JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2147136215 2022-04-18 15:36:05 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2147136215 References JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2148586294 2022-04-19 13:31:38 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2148586294 Uses in Biomedical Research #2 JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2148588373 To study on mechanisms on stem cell regulation in skin

Link: https://doi.org/10.1371/journal.pone.0064223

This study focuses on hair cycling mechanism which was poorly understood in the past. B6 nude is a hairless mouse so it is ironic to use this mouse as a model of study. However, researchers of this study have found that the Foxn1 mutation in the B6 Nude is very useful to demonstrate the effects of a blockage in the expression of keratins on epithelial lineage differentiation, even down to the level of the least-committed epithelial stem cells. Foxn1 deficiency in B6 Nude has found to caused an upregulation of Lhx2 gene which promotes hair cycling but downregulation of other markers such as CyclinD1 which leads to poor extension of epithelial stem cell niches in skin. Therefore, researchers of this study found that Foxn1 mutation has a strong impact on mechanism of the terminal keratinocytic differentiation (Bohr S, 2013).


]]> 2022-04-19 13:32:56 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2148588373 Uses of Biomedical Research #3 JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2148588812 To study on regenerative skin wound healing

Link: https://doi.org/10.1186/s12864-016-3401-z 

Neotenic phenomenon has been observed in B6 Nude mice. Neoteny is the retainment of juvenile characteristics in adulthood. Based on this study, the Foxn1 gene appears to be the main reason for controlling the developmental program and skin maturation. In B6 nude, this gene is mutated to be inactive. So, an inactive form of the Foxn1 gene causes the thymus agenesis and deficiency of T-cells. 
This study suggests that deficiency of Foxn1 gene plays a crucial role in skin regeneration which leads to scar-free injury. This makes B6 Nude a potential model for regenerative healing (Kur-Piotrowska et al, 2017).]]> 2022-04-19 13:33:11 UTC https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2148588812 Animal Husbandry JestherChong_u2004178 https://padlet.com/JestherChong_u2004178/p9s7mrpbcsh6fkaj/wish/2148593077 MICROENVIRONMENT
B6 Nude are housed in a specific pathogen-free room since these mice are very susceptible to any infections from mild to severe. Therefore, a high barrier of protection is needed to protect them. Use of microisolator, individually ventilated cage (IVC) is recommended for these strain of mice. Food, water, bedding, enrichment and anything that will be in contact with the mice are required to be sterilized beforehand. (Jim Yeadon, 2013)

MACROENVIRONMENT
Light-Dark Cycle:
14-hour light/10-hour dark cycle or 12 light/12 dark cycle.

Temperature and Humidity:
Temperature of 18°C - 23°C is optimal. Humidity of 40% - 60% is preferred.

Noise Level:
Less than 65 decibles

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