Ultrastructure of initial nasal process cell fusion in spontaneous and 6-aminonicotinamide-induced mouse embryo cleft lip

A search was made for cell ultrastructure differences in the initial fusion process of the medial and lateral nasal processes in mouse embryos of the following types: A/J with 12% cleft lip (CL), CL/Fr with 23% CL--both cleft-lip-predisposed strains, CL/Fr 6-aminonicotinamide (6AN)-treated (94% CL) and controls from the C57BL/6 strain (0% CL) and dancer stock (0% CL). No detectable differences were found between the A/J and CL/Fr strains and the controls in the epithelial cells showing initial contact and fusion. Epithelial surfaces not in contact in controls and where clefts were developing were smooth. Cells approaching or in contact had cell projections, intercellular junctions, desmosomes, and microfilaments demonstrating firm contact between the apposed epithelia. It has been postulated that spontaneous cleft lip was due to a predisposing face shape bringing about a failure of contact in some embryos and in others where contact was achieved fusion was normal. These data support this view. The situation, however, in 6AN-treated embryos is different. A few 6AN-treated embryos showed abnormal contact that appeared malpositioned and tenuous. The teratogen also caused increased cell death and a denser epithelium and mesenchyme. Thus 6AN-induced cleft lip could be due to the epithelial cell changes and/or to the reduction in size of the nasal processes.     

Interaction between the splotch mutation and retinoic acid in mouse neural tube defects in vitro

The interaction between the splotch gene (Sp) and all-trans retinoic acid (RA) was investigated using cytogenetically marked Sp/+ and +/+ mouse embryos cultured in the presence of RA. Retinoic acid retarded the development of and had a teratogenic effect on mouse embryos in culture. In particular, RA had seemingly opposite effects on the posterior neural tube, inducing abnormally early fusion in some embryos and causing a dose-dependent delay in others. When the effects of RA on identified Sp/+ and +/+ embryos were compared, the only observed difference in their responses was in the degree of the delay in posterior neuropore (PNP) closure. At the end of the culture period, among the untreated control embryos, the Sp heterozygotes showed retardation of PNP closure compared to +/+ embryos. In addition, the RA treatment was found to have induced a greater delay in posterior neural tube closure in Sp/+ than in +/+ embryos. The basis for this difference in response to RA is presumed to be the retardation of PNP closure that is caused by the Sp gene in heterozygous form. The effects of the gene and the teratogen are additive and the gene carriers thus have greater mean PNP lengths at the end of culture. Since the length of the PNP is an indication of an embryo's likelihood of developing spina bifida, this provides an explanation for the observation that Sp/+ embryos are more sensitive to the spina bifida-causing effects of RA than are +/+ embryos.     

Increased susceptibility to 6-aminonicotinamide-induced cleft lip of heterozygote Dancer mice

Dancer heterozygotes (Dc/+) very rarely have cleft lip and show a dancing behaviour due to inner ear defects while homozygotes (Dc/Dc) have cleft lip. Males of the two genotypes Dc/+ and +/+ were mated to C3H strain and R stock females and Dc/+ males to Dc/+ females. On day 10/8 of gestation females were treated with 6-aminonicotinamide (6AN) at either 19 mg/kg or 28.5 mg/kg followed 3 h later by a protective dose of nicotinamide. Controls were untreated. Both 6AN treatments caused a significant increase in cleft lip to between 25% and 29% for crosses of Dc/+ males to C3H and R females whereas crosses with +/+ males gave 0% cleft lip. In the controls the cleft lip frequency was: for Dc/+ X Dc/+ 14%, Dc/+ X C3H 1.4%, and for the other three crosses 0%. The four crosses given the high dose of 6AN and the +/+ X C3H and Dc/+ X R cross at the low dose showed significantly increased resorption rates to between 23% and 47% over the control rates of from 5% to 11%. The presence of the Dc gene increased the susceptibility to cleft lip caused by 6AN.     

Abnormalities of neural tube formation in pre-spina bifida splotch-delayed mouse embryos

The splotch-delayed homozygous mutant (Spd/Spd) develops spina bifida with or without exencephaly, has spinal ganglia abnormalities, and delays in posterior neuropore closure and neural crest cell emigration. The heterozygote (Spd/+) has a pigmentation defect, and occasionally neural tube defects. To investigate the underlying mechanisms, we compared the neuroepithelium in the posterior neuropore region of cytogenetically identified 15-18 somite pair Spd/Spd, Spd/+, and +/+ mouse embryos by transmission electron and light microscopy. The notochordal area and cell number in the non-fused neuroepithelium region of Spd/Spd and Spd/+ embryos were significantly reduced compared to those of normal (+/+) embryos, which suggests an abnormality in notochord elongation. In the mesoderm, the mean cell number and mean ratio of cell number to area in the non-fused region were significantly lower in the Spd/Spd compared with +/+ embryos. The distance of exposed neuroepithelium above the mesoderm in the just-fused region was significantly lower in the Spd/Spd versus +/+ embryos, which may indicate an insufficient force exerted by the mesoderm during neural tube closure. Within the neuroepithelium, significantly more intercellular space was found in Spd/Spd than in +/+ embryos indicating disorganization. The basal lamina was poorly organized and the formation delayed around the neural tube in Spd/Spd and Spd/+ embryos. All together, these results suggest an early abnormality in interactions among the neuroepithelium, mesoderm, and notochord, which may lead to the delay or inhibition of neural tube closure observed in Spd/Spd mutants.     

Enhanced susceptibility of mouse embryos heterozygous for oligosyndactyly (Os/+) to mitomycin C-induced skeletal abnormalities

The mouse mutation, oligosyndactyly (Os), results in syndactyly, muscle anomalies, and deficiency of nephrons in heterozygous animals and early embryonic lethality in homozygotes. Since the homozygous lethality results from mitotic arrest with intact spindles at the time of implantation, we have hypothesized that the heterozygous manifestations may result from impairment of cell proliferation in regions with high proliferative rates. To test this hypothesis, Os/+ and +/+ mouse embryos at 6.5 days of gestation were exposed to mitomycin C (MMC), an agent that causes a high degree of embryonic cell death which is "compensated" for by a period of rapid cell proliferation. 17.9% of MMC-treated +/+ fetuses had fused vertebrae, a significant increase over untreated fetuses, and this frequency was further increased to 33.6% in MMC-treated Os/+ fetuses. Saline treated Os/+ and +/+ fetuses showed the same low rate (0-3%) of vertebral fusion. These results indicate that Os/+ embryos have an increased sensitivity to the vertebral fusion-inducing effect of MMC at 6.5 days of gestation, a finding compatible with the hypothesis that rapid cell proliferation may be impaired in Os/+ embryos and fetuses.     

Mutant gene expression in mouse aggregation chimeras. 8. The effect of the white gene on coat pigmentation

Aggregation of mouse embryos produced 11 chimaeras Miwh/+C/C----+/+c/c and 8 chimaeras +/+C/C----+/+c/c (control). Chimaerism was detected by mosaicism of coat retinal pigment epithelium and by electrophoretic pattern of glucose phosphate isomerase. All chimaeras showed a common pattern of pigmented and unpigmented hair regions that alternated as stripes of different length and width and extended from spine in lateral-ventral direction. However, white coat color predominated in Miwh/+C/C----+/+c/c chimaeras due to a higher proportion of unpigmented zones as well as to weakening of hair color in pigmented areas. Besides, distal regions of limbs were always unpigmented in Miwh/+C/C----+/+c/c chimaeras and completely or partially pigmented in +/+C/C----+/+c/c chimaeras. Pigmented hair regions are often located on the ventral trunk surface where the Miwh/+ heterozygotes usually had an unpigmented spot. The examination of hairs, taken from the same regions of gray coloration, revealed the presence of pigmented, unpigmented and mosaic hairs. The proportion of unpigmented hairs was much higher in Miwh/+C/C----+/+c/c chimaeras than in +/+C/C----+/+c/c chimaeras. The data obtained indicate that a single Miwh gene dose reduced proliferative activity of melanoblasts which resulted in weakening of coat pigmentation.     

Evidence for Mitotic Recombination in W(ei)/+ Heterozygous Mice

A number of alleles at coat color loci of the house mouse give rise to areas of wild-type pigmentation on the coats of otherwise mutant animals. Such unstable alleles include both recessive and dominant mutations. Among the latter are several alleles at the W locus. In this report, phenotypic reversions of the Wei allele at the W locus were studied Mice heterozygous in repulsion for both Wei and buff (bf) [i.e. Wei+/+bf] were examined for the occurrence of phenotypic reversion events. Buff (bf) is a recessive mutation, which lies 21 cM from W on the telomeric side of chromosome 5 and is responsible for the khaki colored coat of nonagouti buff homozygotes (a/a; bf/bf). Two kinds of fully pigmented reversion spots were recovered on the coats of a/a; Wei+/+bf mice: either solid black or khaki colored. Furthermore phenotypic reversions of Wei/+ were enhanced significantly following X-irradiation of 9.25-day-old Wei/+ embryos (P less than 0.04). These observations are consistent with the suggestion of a role for mitotic recombination in the origin of these phenotypic reversions. In addition these results rise the intriguing possibility that some W mutations may enhance mitotic recombination in the house mouse.     

Motility characteristics of sperm from the uterus and oviducts of female mice after mating to congenic males differing in sperm transport and fertility

Motile sperm were videotaped after removal from the uterus and isthmus of the oviducts of female mice 1 h after mating with congenic males carrying none, one, or two t complexes. Males carrying one t complex (tw32/+) are fertile, and sperm carrying the t complex have an advantage in fertilization; males carrying two complexes (tw32/t0) are sterile. For each sperm, 2 sec of movement of the head-midpiece junction were traced from the videotape. For each tracing, five motility parameters were used: curvilinear velocity (Vc), and index of the sperm's mean swimming speed; coefficient of variation of move length (CVML), an index of speed constancy; progressiveness ratio (PR), an index of all deviation of the sperm's movement from a straight line; linear index (LI), an index of the straightness of the sperm's trajectory; and curvilinear progressiveness ratio (PRc), an index of the degree of lateral oscillation about that trajectory. Uterine sperm from fertile males were progressive, with straight trajectories and little lateral oscillation. There were no consistent differences in any motility parameter between uterine sperm from tw32/+ and congenic +/+ males. Uterine sperm from sterile tw32/t0 males were extremely slow and showed very little progressive movement, which could explain their lack of transport to the oviduct. For all fertile males, isthmic oviductal sperm differed significantly from uterine sperm in every motility parameter except Vc: isthmic sperm were less consistent in swimming speed, and less progressive with less straight trajectories and more lateral movement. One or more of these motility characteristics may be related to hyperactivation. A large proportion of isthmic sperm from tw32/+ males had nonlinear trajectories (LI less than .50); these nonlinear sperm were faster than nonlinear isthmic sperm from congenic +/+ males. These motility characteristics of isthmic sperm from tw32/+ males may be related to hyperactivation, or to their previously observed abnormal transport within the oviduct.     

Reduced epithelial surface activity is related to a higher incidence of facial clefting in A/WySn mice

The epithelial surfaces of the facial primordia were evaluated by scanning electron microscopy (SEM) during primary palatogenesis in two genetically related mouse strains, the A/J and the A/WySn strains. These two strains were selected because the reported frequency of spontaneous cleft lip with or without cleft palate [CL(P)] in the A/J strain approximates 0%, whereas the spontaneous frequency of CL(P) in the A/WySn strain is 20-30%. The embryos were examined prior to (two to six tail somites), during (seven to ten tail somites), and after (ten to 14 tail somites) primary palate fusion. During fusion, epithelial surface activity (characterized as cellular debris, dissociated cells, cellular projections, and epithelial bridging) was more pronounced in A/J embryos. A/WySn embryos with spontaneous cleft lip exhibited a marked deficiency in epithelial activity when compared to their normal littermates. No discernible differences were detected in the facial morphology, with the exception of the distal end of the medial nasal prominence, which appeared longer in the A/J strain. This study suggests that the degree of epithelial surface activity at the putative site of fusion and the relative length of the medial nasal prominence may account for the observed differences in facial clefting of the two strains. Face shape, related to prominence divergence, was similar in the two strains and could not explain the higher incidence of clefting observed in the A/WySn strain.     

Morphological observations in normal primary palate and cleft lip embryos in the Kyoto collection

Normal developmental events during human primary palate formation and alterations associated with cleft lip remain poorly defined. The purpose of this study was to analyze serially sectioned human embryos to identify morphological changes during normal palatal closure and alterations associated with failure of palatal formation. Normal and cleft embryos from the histological collection at the Congenital Anomaly Research Center at the University of Kyoto were studied and photographed for detailed evaluation. Seven serially sectioned cleft lip embryos of stages shortly after primary palate formation (Streeter-O'Rahilly stages 19, 20, and 22) with unilateral or bilateral clefts with varying degrees of clefting were studied. In the normal Kyoto embryos, initial nasal fin (epithelial seam) formation was observed between the medial nasal process and the lateral nasal and maxillary processes at stage 17. During stages 18 and 19, the nasal fin epithelium was replaced by an enlarging mesenchymal bridge, as the maxillary processes united with the medial nasal processes to form the primary palate. The most prominent features observed in the cleft embryos were a reduced thickness of mesenchymal bridging between the medial nasal and maxillary processes, with an excessive amount of epithelium at the junctions between these processes. With ingrowth of the maxillary processes, greater cell dispersion and apparent extracellular matrix accumulation were observed in the medial nasal region. During closure of the primary palate, terminal branches of the maxillary nerve crossed the mesenchymal bridge to the medial nasal region. The partial clefts had reduced maxillary ingrowth and smaller union areas with the medial nasal process. Detailed studies of experimental animal models are required to identify regional growth required for contact between the facial prominences, to clarify the mechanisms of mesenchymal ingrowth and epithelial displacement during palatal formation, and to identify local and/or general factors causing alterations that lead to primary palatal clefting.     

Adipose tissue in offspring of Lepr(db/+) mice: early-life environment vs. genotype

Gravidas with obesity and diabetes ("diabesity") may transmit this syndrome to their children through genetic and nongenetic mechanisms. Here, we used the Lepr(db/+) diabese mouse to examine the magnitude of these transmission modes, focusing on adipose tissue (AT). We compared the following six groups: wild-type (+/+) offspring from +/+ or db/+ dams (different early life environment) and db/+ offspring from db/+ dams, fed a standard or high-fat diet. Weight gain (0-8 wk) was higher in +/+ offspring from db/+ vs. +/+ mothers, and even higher in db/+ vs. +/+ offspring from db/+ mothers. In addition, we observed a stepwise increase in AT and adipocyte size in +/+ from +/+ mice, +/+ from db/+ mice, and db/+ mice at 8 wk. Differences in weight and adiposity between +/+ offspring from db/+ vs. +/+ dams were more pronounced in males than in females. Leptin and apelin mRNA levels in white and brown AT were higher in +/+ offspring from db/+ vs. +/+ dams; however, leptin, apelin, and tumor necrosis factor-alpha expression were boosted more robustly in db/+ offspring. The high-fat diet amplified AT differences between db/+ vs. +/+ offspring from db/+ dams, but not between +/+ offspring from db/+ vs. +/+ dams. Moreover, db/+ but not +/+ offspring from db/+ mothers were insulin-resistant and hyperinsulinemic after a glucose challenge. In conclusion, the genetic transmission of the diabesity phenotype clearly prevailed, but the early-life diabesity environment had discernible effects on postnatal weight gain as well as on adipocyte size and adipokine expression at a postpubertal age.     

Histological studies of normal and mutant mouse embryo hearts (a glycogen content study)

Mutant tail-short (Ts/+) embryos are developmentally retarded compared with normal +/+ litter mates. The development of the heart of Ts/+ embryos is severely affected if the tail-short gene is transferred to a new genetic (50% A/Gr) background. The aim of the present study was to investigate the glycogen content of the sinus muscle, the cushion and the atrial and ventricular walls of the heart. In normal embryos the sinus muscle is well developed by the 15th day post coitum (d.p.c.) and is crowded with glycogen granules. In Ts/+ mutant embryos, on the other hand, the development of this muscle is retarded and it contains only a little, diffusely distributed glycogen. The atrial and ventricular walls of embryos with a normal heart are well trabeculated and contain a large quantity of glycogen granules, while in mutant embryos they are less well trabeculated and contain only a little glycogen in a diffuse of finely granular form.     

Nasal pit formation in the hamster: a transmission and scanning electron microscopic study

The surface morphology of cells comprising the nasal placode and adjacent body surface was examined by transmission and scanning electron microscopy during nasal pit formation in hamster embryos ranging in age from $\text{8}\text{1}\text{4}$ to $\text{9}\text{1}\text{2}$ days post coitum. A sharp distinction between the apical surface appearance of cells of the nasal epithelium and cells of the surrounding periderm develops at the periphery of the nasal placode. Periderm cells increase in surface area, exhibit a change in the distribution of surface microvilli, and many acquire a single cilium per cell. Cells of the nasal placode retain a dense surface coat of microvilli and exhibit relatively smaller apical surface areas. Olfactory rods can be positively identified on the basis of their ultrastructure at the nasal groove stage. The ventral margin of the nasal groove does not initially depend on the maxillary process, but is bounded by the lateral and medial nasal processes. From their earliest development the oral and nasal cavities appear to be separated in this species.     

Do endogenous opioid peptides mediate the effects of photoperiod on release of luteinizing hormone and prolactin in ovariectomized ewes?

Three experiments were done to determine if endogenous opioid peptides (EOPs) mediate the effects of photoperiod on release of luteinizing hormone (LH) and prolactin (Prl) in ovariectomized (OVX) ewes. Intravenous infusions of 0.5 naloxone X h-1 X kg body weight-1 for 3.5 h increased (P less than 0.01) mean plasma concentrations of LH and decreased (P less than 0.025) mean interpulse interval (period) of LH pulses in OVX ewes exposed to long day lengths (16L:8D). Infusions of either 1.0 or 2.5 mg morphine-SO4 X h-1 X kg-1 for 3 h increased (P less than 0.005) the period of LH pulses and increased (P less than 0.005) concentrations of Prl in OVX ewes during the breeding season. In OVX ewes exposed to long (16L:8D) or short (8L:16D) day lengths infusions of naloxone increased (P less than 0.05) mean concentrations of LH, whereas morphine decreased (P less than 0.01) mean concentrations of LH. These effects were attributed to changes in period of LH pulses (P less than 0.001). The drug X photoperiod interactions were not significant for LH parameters. Naloxone did not affect Prl release in either long- or short-day groups, but morphine increased (P less than 0.001) Prl release during long and short day lengths. The effect of morphine on Prl release was more pronounced in ewes exposed to long day lengths than in those exposed to short day lengths. In conclusion, EOPs inhibit the LH pulse generator in OVX ewes. However, it is doubtful that the EOPs mediate the steroid-independent effects of photoperiod on LH release. The results also suggest that photoperiod may influence Prl release via opiate neurons.     

Cranial anomaly of homozygous rSey rat is associated with a defect in the migration pathway of midbrain crest cells

Craniofacial development of vertebrates depends largely on neural crest contribution and each subdomain of the crest-derived ectomesenchyme follows its specific genetic control. The rat small eye ( rSey ) involves a mutation in the Pax-6 gene and the external feature of rSey homozygous embryos exhibits craniofacial defects in ocular and frontonasal regions. In order to identify the mechanism of craniofacial development, we examined the cranial morphology and migration of cephalic crest cells in rSey embryos. The chondrocranial defects of homozygous rSey embryos primarily consisted of spheno-orbital and ethmoidal anomalies. The former defects appeared to be brought about by the lack of the eye. In the ethmoid region, the nasal septum and the derivative of the medial nasal prominence were present, while the rest of the nasal capsule, as well as the nasal and lachrymal bones, were totally absent except for a pair of cartilaginous rods in place of the nasal capsule. This suggests that the primary cranial defect is restricted to the lateral nasal prominence derivatives. Dil labeling revealed the abnormal migration of crest cells specifically from the anterior midbrain to the lateral nasal prominence in homozygous rSey embryos. Pax-6 was not expressed in the crest cells but was strongly expressed in the frontonasal ectoderm. To determine whether or not this migratory defect actually resides in environmental cues, normal midbrain crest cells from wild-type embryos were labeled with Dil and were orthotopically injected into host rSey embryos. Migration of the donor crest cells into the lateral nasal prominence was abnormal in homozygous host embryos, while they migrated normally in wild-type or heterozygous embryos. Therefore, the cranial defects in rSey homozygous embryos are due to inappropriate substrate for crest cell migration towards the lateral nasal prominence, which consistently explains the cranial morphology of homozygous rSey embryos.     

Site of fidget gene action and its interaction with the ocular retardation gene in cultured mouse embryo retinas

The eye rudiments of 10 and 11 days old mouse embryos of the genotypes +/+ +/+, fi/fi +/+, +/+ or/or, fi/fi or/or and 11 days old embryos of the genotype fi/+ or/+ were cultivated in vitro during 24, 48 and 72 hrs. The expression of the fi gene was shown in the cells of the cultivated fi/fi +/+ retina: its proliferative activity was inhibited. The fi gene was not active in the cells of the developing lens and the anomalies of the latter in homozygotes arose secondarily, due to the inhibition of growth of the retinal rudiment. The fi and or genes interacted synergically in the cultivated fi/fi or/or retina, thus resulting in the marked inhibition of its mitotic activity. This suggests that both the genes act in the retinal cells and, apparently, affect different links of the biochemical chain of events in the preparation of DNA replication.     

A relationship between cerebellar Purkinje cells and spatial working memory demonstrated in a lurcher/chimera mouse model system

New emphasis has been placed upon cerebellar research because of recent reports demonstrating involvement of the cerebellum in non-motor cognitive behaviors. Included in the growing list of cognitive functions associated with cerebellar activation is working memory. In this study, we explore the potential role of the cerebellum in spatial working memory using a mouse model of Purkinje cell loss. Specifically, we make aggregation chimeras between heterozygous lurcher (Lc/+) mutant embryos and +/+ (wildtype) embryos and tested them in the delayed matching-to-position (DMTP) task. Lc/+ mice lose 100% of their Purkinje cells postnatally due to a cell-intrinsic gain-of-function mutation. Lc/+<->+/+ chimeras therefore have Purkinje cells ranging from 0 to normal numbers. Through histological examination of chimeric mice and observations of motor ability, we showed that ataxia is dependent upon both the number and distribution of Purkinje cells in the cerebellum. In addition, we found that Lc/+ mice, with a complete loss of Purkinje cells, have a generalized deficit in DMTP performance that is probably associated with their motor impairment. Finally, we found that Lc/+<->+/+ chimeric mice, as a group, did not differ from control mice in this task. Rather, surprisingly, analysis of their total Purkinje cells and performance in the DMTP task revealed a significant negative relationship between these two variables. Together, these findings indicate that the cerebellum plays a minor or indirect role in spatial working memory.     

Resistance artery remodeling in deoxycorticosterone acetate-salt hypertension is dependent on vascular inflammation: evidence from m-CSF-deficient mice

Deoxycorticosterone acetate (DOCA)-salt hypertension has an important endothelin-1 (ET-1)-dependent component. ET-1-induced vascular damage may be mediated in part by oxidative stress and vascular inflammation. Homozygous osteopetrotic (Op/Op) mice, deficient in macrophage colony-stimulating factor (m-CSF), exhibit reduced inflammation. We investigated in osteopetrotic (Op/Op) mice the effects of DOCA-salt hypertension on vascular structure, function, and oxidative stress, the latter as manifested by reduced nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase activity. Mice were implanted with DOCA (200 mg/mouse, under 5% isofluorane anesthesia) and given saline for 14 days. Systolic blood pressure (mmHg) was significantly increased (146 +/- 2 and 138 +/- 1; P < 0.001 vs. basal 115 +/- 3 and 115 +/- 3, respectively) by DOCA-salt in wild-type (+/+) and heterozygous (Op/+) mice, but not in Op/Op mice (130 +/- 1 vs. basal 125 +/- 3). Norepinephrine contractile response was significantly enhanced, while acetylcholine endothelium-dependent vasodilation was significantly impaired in DOCA-salt-treated +/+ and Op/+ mice compared with control mice. No changes in norepinephrine-induced contraction and acetylcholine-induced relaxation were observed in DOCA-salt Op/Op mice. DOCA-salt +/+ and Op/+ mice had significantly increased mesenteric resistance artery media-to-lumen ratio and media cross-sectional area, neither of which were altered in Op/Op mice. Basal vascular superoxide production and NAD(P)H oxidase activity, vascular cell adhesion molecule-1 expression, and macrophage infiltration were significantly increased only in DOCA-salt +/+ mice. Thus m-CSF-deficient mice developed less endothelial dysfunction, vascular remodeling, and oxidative stress induced by DOCA-salt than +/+ and Op/+ mice, suggesting that inflammation may play a role in DOCA-salt hypertension, a model that results in part from effects of ET-1, which has proinflammatory actions.     

Mutations of GADD45G in rabbits cause cleft lip by the disorder of proliferation,apoptosis and epithelial-mesenchymal transition (EMT)

The cleft lip with or without cleft palate (CL/P) is one of the most common congenital defects in humans. Genome-wide association studies (GWAS) have been widely used for identifying candidate genes, and different genes or chromosomal regions have shown strong evidence for the presence of causal genes in CL/P. To date, two independent GWAS have identified GADD45G as influencing risk for CL/P. However, there is no animal model evidence about GADD45G related to CL/P. Here, we reported the generation of a novel GADD45G mutated rabbit model by CRISPR/Cas9 and CRISPR-based BE4-Gam systems. The homozygous (GADD45G^−/−) while not heterozygous (GADD45G^+/−) pups died after birth due to severe craniofacial defects of unilateral or bilateral cleft lip (CL). Moreover, the disorder of proliferation, apoptosis and epithelial-mesenchymal transition (EMT) were also determined in the medial and lateral nasal processes (MNP and LNP) of the embryonic day 13 (E13) GADD45G^−/− rabbits, which compared with the normal wild type (WT) rabbits. Thus, our study confirmed for the first time that loss of GADD45G lead to CL at the animal level and provided new insights into the crucial role of GADD45G for upper lip formation and fusion.