Gene Description

Symbol:  Hprt

Gene:  hypoxanthine-guanine phosphoribosyltransferase

Chromosome:  X

Background Strain:  C57BL/6J

Strain Development:  This is a C57Bl/6J congenic strain that carries a portion of the X chromosome from M. spretus which has been maintained heterozygous at the Hprt locus. This strain was initially developed by mating a C57BL/6J to a M. spretus and then mating F1 females to C57BL/6J males and selecting females heterozygous at the Hprt locus for the next matings. This was continued for 12 generations at which time sibling mating was performed with males that were hemizygous for the Hprt^a allele and females that are heterozygous for the Hprt^a allele. Sibling mating has now exceeded 30 generations.

Other Strain Names:  AT24 (allelic transfer 24);

Summary of Phenotype

Historically, these mice have a reproductive phenotype in which they are capable of having two normal sized litters before production drops off as compared to the C57Bl/6 in the facility. The finding of vaginal plugs decreases as the production drops off. The females of this strain have also been found to have hyperplastic placentas and males demonstrate lower testicular weights and testicular degeneration.

In this study, the testicular weight of the mutant was less than that of the C57BL/6J control and more degenerative tubules were found histologically, however the motility and concentration of the sperm were within normal limits. In contrast, no consistent histological differences in reproductive organ histomorphology were seen between mutant and wild type females

Summary - Gross Findings

On gross necropsy, the mutant female (19.7g) weighed less than the control female (24.2g). The mutant male (23.63g) weighed less than the control male (29.3g). A fluid distended uterus was noted for the mutant female. No gross lesions were observed in the control female. No gross lesions were observed for either the control or mutant male. The testicular weight of the mutant male (0.0671g) was less than that of the mutant male (0.1018g).

Organ/Body Weights

	C57BL/6J.SPRET-Hprta female	C57BL/6J.SPRET-Hprta male	C57BL/6J control female	C57BL/6J control male
adrenal glands (single)	0.0750g	0.0290g	0.0133g	0.0024g
body weight	19.70g	23.63g	24.20g	29.3g
heart	0.1241g	0.1412g	0.1377g	0.1792g
left kidney	0.1286g	0.1474g	0.1633g	0.2538g
liver	1.0585g	1.2042g	1.2551g	1.1637g
ovaries	0.0082g		0.0079g
spleen	0.0625g	0.0583g	0.0746g	0.0791g
testicle (left without epididymis)		0.0671g		0.1018g

Summary - Histology

Moderate germinal epithelial degeneration and mild interstitial cell hyperplasia were evident in the testes of the mutant male.

The uteri of mutant and control females were observed to be at different stages. The control uterus was in proestrus. The mutant female uterus was not definitively staged. A copulatory plug was observed in the vagina of the mutant mouse, and mature spermatozoa were observed within the uterine lumen. No

Other histologic findings are believed to represent background lesions and are not believed to be genotype-related. However, examination of additional mice is necessary to confirm or refute this suppostion. Lesions, for which the role of genotype is unknown (an likely irrelevant), include: mild focal periglomerular fibrosis, found in the mutant male and mutant female, but not in control mice; mild diffuse lipidosis, found in the sciatic nerve of the mutant female; and perivascular inflammatory aggregates found in the exorbital gland and liver of the mutant male.

Phenotypic Abnormalities - Histology
C57BL/6J.SPRET-Hprt^a

Organ	Lesion	Sex	Age	# Affected	Image(s)
testes	interstitial cell hyperplasia	M	14w	1/1
testes	moderate germinal epithelial degeneration	M	14w	1/1

Click on lesion for full description. Click on image for larger view.

Complete Data - Histology

(Click on lesion for full description.)

	C57BL/6J.SPRET-Hprta female	C57BL/6J.SPRET-Hprta male	C57BL/6J control female	C57BL/6J control male
adrenal gland(s)
corticomedullary hemorrhage	+	-	+	-
aorta
no lesions	-	-	-	-
brown fat
no lesions	-	-	-	-
bulbourethral gland
no lesions		-		-
cecum
no lesions	-	-	-	-
cerebellum
no lesions	-	-	-	-
cerebrum
no lesions	-	-	-	-
cervix
no lesions	-		-
clitoral gland
no lesions	-		-
coagulating gland
no lesions		-		-
costrochondral junction
no lesions	-	-	-	-
diaphragm
no lesions	-	-	-	-
distal colon
no lesions	-	-	-	-
duodenum
no lesions	-	-	-	-
epididymis
no lesions		-		-
exorbital gland
perivascular lymphoid infiltrates	-	+	-	-
eye
nuclear cataract	-	-	-	+
femoral bone marrow
no lesions	-	-	-	-
femur
no lesions	-	-	-	-
Harderian gland
no lesions	-	-	-	-
heart
mild pigment deposition on valves	+	+	+	-
ileum
no lesions	-	-	-	-
incisor tooth
no lesions	-	-	-	-
inner ear
no lesions	-	-	-	-
jejunum
no lesions	-	-	-	-
kidneys
mild focal periglomerular fibrosis	+	+	-	-
lacrimal gland(s)
no lesions	-	-	-	-
liver
lymphocytic and neutrophilic aggregate	-	+	-	-
microabscesses	-	-	-	+
lung
no lesions	-	-	-
mammary gland
no lesions	-		-	-
molar tooth
no lesions	-	-	-	-
nasal cavity
no lesions	-	-	-	-
ovary
no lesions	-		-
pancreas
no lesions	-	-	-	-
parathyroid gland
no lesions	-	-	-	-
parotid salivary glands
no lesions	-	-	-	-
penis
no lesions		-
pituitary gland
no lesions	-	-	-	-
preputial glands
no lesions		-		-
prostate gland
no lesions		-		-
proximal colon
no lesions	-	-	-	-
quadriceps muscle
no lesions	-	-	-	-
sciatic nerve
mild diffuse lipidosis	+	-	-	-
skin
no lesions	-	-	-	-
spinal cord
no lesions	-	-	-	-
spleen
hematopoiesis	+	+	+	-
hemosiderosis	+	+	+	-
stifle
no lesions	-	-	-	-
stomach
no lesions	-	-	-	-
sublingual salivary gland
no lesions	-	-	-	-
submand. salivary glands
no lesions	-	-	-	-
testes
moderate germinal epithelial degeneration		+		-
mild multifocal interstitial cell hyperplasia		+		-
thymus
no lesions	-	-	-	-
thyroid gland
no lesions	-	-	-	-
tissue masses
no lesions				-
tongue
no lesions	-	-	-	-
trachea
no lesions	-	-	-	-
urethra
no lesions	-	-	-	-
urinary bladder
no lesions	-	-	-	-
uterus
post-breeding	+		-
proestrus	-		+
vagina
post-breeding	+		-
proestrus	-		+
vaginal plug
normal copulatory plug	+
vesicular gland
no lesions		-		-

Summary - Behavioral Testing

A series of behavioral tests were performed. All 4 mice responded within normal limits.

Complete Data - Behavioral Testing

Reflex Testing

	C57BL/6J.SPRET-Hprta female	C57BL/6J.SPRET-Hprta male	C57BL/6J control female	C57BL/6J control male
visible	wnl	wnl	wnl	wnl
spontaneous behavior	wnl	wnl	wnl	wnl
reaching reflex	wnl	wnl	wnl	wnl
righting reflex	wnl	wnl	wnl
trunk curl	wnl	wnl	wnl	wnl
negative geotaxis	wnl	wnl	wnl	wnl
hanging wire grip test	wnl	wnl	wnl
preyer reflex	wnl	wnl	wnl	wnl
pinna reflex	too active to test	too active to test	too active to test	wnl
vibrissae reflex	wnl	wnl	wnl	wnl
pupillary light reflex	wnl	wnl	wnl

 

Summary - Clinical Chemistry

No genotype associated abnormalties were observed in clinical chemistry analysis.

Complete Data - Clinical Chemistry

	C57BL/6J.SPRET-Hprta female	C57BL/6J.SPRET-Hprta male	C57BL/6J control female	C57BL/6J control male
Glucose (mg/dL)	312	248	207	261
Urea Nitrogen (mg/dL)	14	21	26	15
Creatinine (mg/dL)	0.2	0.2	0.4	0.2
Sodium (mmol/L)	143	149	152	144
Potassium (mmol/L)	3.1	5.5	4.7	4.3
Chloride (mmol/L)	111	111	109	112
Total Protein (g/dL)	4.7	5.1	5.4	4.0
Albumin (g/dL)	2.2	2.2	2.5	1.7
Globulin (g/dL)	2.6	2.9	2.9	2.3
Calcium (mg/dL)	8.8	9.1	9.4	8.9
Phosphorus (mg/dL)				9.5
Cholesterol (mg/dL)	67	73	68	45
Total Bili (mg/dL)	0.1	0.1	0.1	0.5
ALT (U/L)	55	43	29	69
ALP (U/L)	133	109		86
AST (U/L)

Comments:  blank = not done

Summary - Hematology

No genotype associated hematologic abnormalties were observed. Visible clotting was observed in the blood sample of the mutant female that may have affected results from the automated HemaVet 850 (including total WBC count).

Complete Data - Hematology

	C57BL/6J.SPRET-Hprta female	C57BL/6J.SPRET-Hprta male	C57BL/6J control female	C57BL/6J control male
Leukocytes
WBC (x10³/μL)	2.62	4.84	12.94	4.88
Manual differential data (smear submitted)
Segmented Neutrophils (%)	12.00	8.00	3.00	6.00
Band Neutrophils (%)	0.00	0.00	0.00	0.00
Lymphocytes (%)	83.00	90.00	95.00	88.00
Monocytes (%)	5.00	2.00	2.00	6.00
Eosinophils (%)	0.00	0.00	0.00	0.00
Basophils (%)	0.00	0.00	0.00	0.00
Nucleated RBCx (/100RBC)	0.00	0.00	0.00	0.00
Absolute leukocytes numbers calculated from manual differential
Segmented Neutrophils (x10³/μL)	0.31	0.39	0.39	0.29
Band Neutrophils (x10³/μL)	0.00	0.00	0.00	0.00
Lymphocytes (x10³/μL)	2.17	4.36	12.29	4.29
Monocytes (x10³/μL)	0.13	0.10	0.26	0.29
Eosinophils (x10³/μL)	0.00	0.00	0.00	0.00
Basophils (x10³/μL)	0.00	0.00	0.00	0.00
Differential data generated by HemaVet
Segmented Neutrophils (%)	9.93	5.51	14.15	38.89
Lymphocytes (%)	86.54	92.49	80.59	57.99
Monocytes (%)	3.05	1.72	4.10	2.44
Eosinophils (%)	0.31	0.29	0.91	0.50
Basophils (%)	0.17	0.00	0.25	0.19
Absolute leukocytes numbers calculated from HemaVet differential
Segmented Neutrophils (x10³/μL)	0.26	0.27	1.83	1.90
Lymphocytes (x10³/μL)	2.27	4.48	10.43	2.83
Monocytes (x10³/μL)	0.08	0.08	0.53	0.12
Eosinophils (x10³/μL)	0.01	0.01	0.12	0.02
Basophils (x10³/μL)	0.00	0.00	0.03	0.01
Red blood cell parameters
RBC (M/μL)	7.94	11.46	10.14	10.84
Hemoglobin (g/dL)	9.8L	14.60	13.10	13.50
Hematocrit (%)	42.60	58.90	51.50	56.00
MCV (fL)	53.60	51.40	50.80	51.70
MCH (pg)	12.30	12.70	12.90	12.50
MCHC (g/dL)	23.00	24.80	25.40	24.10
Red Cell Distribution Width (%)	19.30	20.40	20.40	21.10
Platelet parameters
Platelets (x10³/μL)	473.00	321.00	745.00	625.00
MPV (fL)	5.10	5.10	5.20	4.70

Sample 1 has visible clotting.

Summary - Reproduction

Male reproductive biology was assessed via histology and semen analysis. Moderate testicular degeneration was evident in the mutant male with 18.7% of seminiferous tubules classified as degenerative. Spermatozoa concentration and motility (epididymal sample) were within normal limits.

Female reproductive biology was assessed via histology of the reproductive tract (vagina, uterus, ovaries) and a quantification of follicular development. The latter was achieved by examining serial sections (50 micrometers apart) of mutant and control ovaries and counting the number of small follicles, medium follicles, large follicles, premature antral follicles, degenerating follicles, small degenerating follicles and corpora lutea. Three mutants and one control mouse were evaluated. These analyses revealed no clear differences in reproductive organ histomorphology.

Complete Data - Reproduction

SEMEN ANALYSIS

epididymis

	C57BL/6J.SPRET-Hprta male
cell concentration	13.8M/mL
motility	71%

Summary

Methods: 2 epididymides were collected and placed in 0.5mL isotonic solution in a 4-well dish. The epididymides were incubated for 10minutes. A sample was then taken from the cell suspension and counted.

ASSESSMENT OF OVARIES

Ovarian Histology

	Corpora lutea			Small Follicles			Medium Follicles			Large Follicles
Ovary	1	2	Both	1	2	Both	1	2	Both	1	2	Both
C57BL/6J	1.37*	1.82	3.19	2.37	1.91	4.28	3.18	3.64	6.82	12.10	11.75	23.85
C57BL/6J SPRET-Hprta 1	1.72	4.45	6.16	3.15	2.75	5.90	3.00	3.45	6.45	10.70	13.65	24.35
C57BL/6J SPRET-Hprta 2	1.50	2.72	4.22	9.35	5.30	14.65	6.15	6.65	12.80	16.35	14.35	30.70
C57BL/6J SPRET-Hprta 3	0.79	0.43	1.21	4.65	3.00	7.65	2.15	3.72	5.86	6.85	11.20	18.05
C57BL/6J SPRET-Hprta ave			3.86			9.40			8.37			24.37

* total count / number of levels examined

	Small Degenerate Follicles			Degenerate Follicles			Premature Antral Follicles
Ovary	1	2	Both	1	2	Both	1	2	Both
C57BL/6J	11.90	11.80	23.70	1.82	2.00	3.82	0.82	0.27	1.09
C57BL/6J SPRET-Hprta 1	15.00	16.10	31.10	1.15	1.45	2.59	1.86	1.00	2.86
C57BL/6J SPRET-Hprta 2	17.65	6.65	24.30	3.93	3.15	7.08	1.07	0.72	1.79
C57BL/6J SPRET-Hprta 3	2.15	3.72	5.86	1.57	2.43	4.00	0.21	0.65	0.86
C57BL/6J SPRET-Hprta ave			20.42			4.56			1.83

small follicles: includes all follicles less than 20µ in diameter

medium follicles: includes all follicles 20-70µ in diameter

large follicles: includes all follicles greater than 70µ in diameter

small degenerate follicles: less than 70µ diameter structures within the stroma that contain amorphous eosinophilic material that is usually lined by squamous cells and do not contain red blood cells. Squamous-lined small degenerate follicle counts are listed within parentheses beside the total number of counts of small degenerate follicles.

degenerative follicles: well-defined follicles greater than 20µ in diameter with recognizable granulosa cells that show granulosa cell apoptosis; apoptotic bodies can be observed within antral spaces or between granulosa cells; degenerative follicles showing oocyte degeneration and fragmentation were also included within this category

premature antral follicles: follicles with less than 401-600 granulosa cells that display a developing antrum (a well-defined separation [forming a clear space] between granulosa cell layers with minimal to mild apoptosis)

Summary

No clear trends were indentified to suggest differences between mutant and control ovarian histology.

Complete Urinalysis Data

	C57BL/6J.SPRET-Hprta male	C57BL/6J control male
collection
clarity	WNL	WNL
color	WNL	WNL
glucose	-	-
pH	7.5	6.0
specific gravity	1.050	1.068
protein	QNS	++
blood	QNS	-
sediment exam	QNS	QNS
bilirubins	QNS	-
ketones	QNS	QNS
urobilirubins	QNS	QNS

(LEGEND:   + = positive    - = negative    ~ = suspect    QNS = quantity not sufficient    WNL = within normal limits)

Literature Review

• Elliot,R.W., D.R.Miller, D.R.Miller et al.
  
  2001. Genetic analysis of testis weight in an interspecies hybrid congenic strain for Chromosome X. Mammalian Genome. 12: 45-51.



• Hemberger, M.C., R.S. Pearsall, U. Zechner, A orth, S. Otto, F. Ruschendorf, R. Fundele, and RW Elliot
  
  Genetic dissection of X-linked interspcific hybrid placental dysplasia in congenic mouse strains. Genetics. 153: 383-390.