The site of the action of the angora-Y gene and its interaction with the fuzzy-Y gene in the mouse

The site of action of the goY mutant gene was determined in the aggregation chimaeras C57BL-goY/goY----DBA (+/+). Chimerism was detected by mosaicism of coat pigmentation and electrophoretic pattern of glucose phosphate isomerase. In 28-day-old chimaeras the regions of light-brown coat alternated black coat, stripes of short hairs alternated those of long hairs. These stripes of different length and width extended from spine in lateral-ventral direction. The hairs plucked from long hairs stripes had a similar length that those of goY/goY mice of same age, but the hairs plucked from short hair stripes corresponded to the hair length of +/+ mice. These data show that the goY gene acts in epidermal cells of hair follicles and its expression is autonomous. It has been established that in double homozygotes goY/goYfzY/fzY both mutant genes are expressed: the considerable increase of hair length as compared to norm--the effect of the goY gene and curly coat--the effect of the fzY gene. In goY/goYfzY/fzY mice during the formation of G1 guard hairs the incomplete expression of the goY gene is observed that is due to the suppression of hair growth by the fzY mutant gene. The fzY gene does not suppress the growth of G2 hairs and therefore the full expression of the goY gene occurs in goY/goYfzY/fzY adult mice.     

The mutant gene wellhaarig disturbs the differentiation of hair follicle cells in the mouse]

First generation (G1) hairs in mice homozygous for the wellhaarig (we) gene are wavy and shorter than in normal mice; basal regions of the hairs are deformed. Follicles of G1 hairs in mid-dorsal region of 8-, 12- and 16-days old we/we mice were examined. Huxley cells of the inner root sheath (IRS) in apical region of hair follicles appeared to be hypertrophied. Cytoplasm of these cells was not stained by basic dyes and showed no birefringence. Cytoplasm of the IRS Henle cells was not stained by basic dyes either. These data indicate that keratinization of the IRS cells is disturbed in mutant homozygotes. The layer of outer root sheath in the we/we mice was thinner than in normal mice; this is probably due to hypertrophy of the IRS cells. The structure of differentiating cells of the hair shaft in normal and mutant mice was similar. The data obtained suggest that abnormal G1 hairs in we/we mice result from disturbance in IRS cells differentiation.     

The origin and development of alopecia in mice homozygous for strong's luxoid gene

Hair follicles are initiated in mice homozygous for Strong's luxoid gene at the normal times. The dermis from 16 days of gestation to nine days after birth lags in development. The adipose layer instead of enlarging at the normal time of three days after birth delays until nine days. The growth of the first cycle hairs is inhibited, particularly on dorsal surfaces. Some follicles of all types degenerate. The surviving follicles enter telogen at seven days after birth, after forming only short unpigmented or poorly-pigmented hairs. Many follicles immediately begin a second cycle of growth, in which more normal hairs develop and a substantial adipose layer forms. No alopecia develops on ventral surfaces, but growth of the first cycle ceases and the second cycle commences earlier than normal; the hairs formed are abnormal. Abnormal hair growth in Strong's luxoid homozygotes may be a result of the retarded growth of the dermis or both defects may be secondary to a more fundamental defect.     

The yeast ser/thr phosphatases sit4 and ppz1 play opposite roles in regulation of the cell cycle

Yeast cells overexpressing the Ser/Thr protein phosphatase Ppz1 display a slow-growth phenotype. These cells recover slowly from alpha-factor or nutrient depletion-induced G1 arrest, showing a considerable delay in bud emergence as well as in the expression of the G1 cyclins Cln2 and Clb5. Therefore, an excess of the Ppz1 phosphatase interferes with the normal transition from G1 to S phase. The growth defect is rescued by overexpression of the HAL3/SIS2 gene, encoding a negative regulator of Ppz1. High-copy-number expression of HAL3/SIS2 has been reported to improve cell growth and to increase expression of G1 cyclins in sit4 phosphatase mutants. We show here that the described effects of HAL3/SIS2 on sit4 mutants are fully mediated by the Ppz1 phosphatase. The growth defect caused by overexpression of PPZ1 is intensified in strains with low G1 cyclin levels (such as bck2Delta or cln3Delta mutants), whereas mutation of PPZ1 rescues the synthetic lethal phenotype of sit4 cln3 mutants. These results reveal a role for Ppz1 as a regulatory component of the yeast cell cycle, reinforce the notion that Hal3/Sis2 serves as a negative modulator of the biological functions of Ppz1, and indicate that the Sit4 and Ppz1 Ser/Thr phosphatases play opposite roles in control of the G1/S transition.     

Auxin and ethylene promote root hair elongation in Arabidopsis

Genetic and physiological studies implicate the phytohormones auxin and ethylene in root hair development. To learn more about the role of these compounds, we have examined the root hair phenotype of a number of auxin- and ethylene-related mutants. In a previous study, Masucci and Schiefelbein (1996) showed that neither the auxin response mutations aux1 and axr1 nor the ethylene response mutations etr1 and ein2 have a significant effect on root hair initiation. In this study, we found that mutants deficient in either auxin or ethylene response have a pronounced effect on root hair length. Treatment of wild-type, axr1 and etr1 seedlings with the synthetic auxin, 2,4-D, or the ethylene precursor ACC, led to the development of longer root hairs than untreated seedlings. Furthermore, axr1 seedlings grown in the presence of ACC produce ectopic root hairs and an unusual pattern of long root hairs followed by regions that completely lack root hairs. These studies indicate that both auxin and ethylene are required for normal root hair elongation.     

Postnatal ovarian follicle development in hypogonadal (hpg) and normal mice and associated changes in the hypothalamic-pituitary ovarian axis

Significant uterine growth occurred in normal and hypogonadal (hpg) mice between Days 7 and 21 but thereafter no further growth was observed in hpg mice. The ovaries of hpg mice were significantly smaller than those of normals at all ages, but there was no significant difference between the number of non-growing follicles in the ovaries of mutants and their normal littermates at any age studied, and normal and hpg mice showed a marked reduction in the number of non-growing follicles during the first month of life. The size and composition of the growing follicle population in hpg mice, however, differed markedly from those in normal animals and by 21 days of age the number of growing follicles in mutants was significantly reduced. There was no significant difference in the number of Type 3b follicles before 60 days of age, but the number of all other follicle types was significantly less in hpg mice at all ages studied. Follicles in which the antrum is fully developed (Type 7 and 8) were never seen in the ovaries of mutants and corpora lutea were never observed. Interstitial tissue development was also very poor in hpg ovaries. The hypothalamic GnRH content in normal mice remained low until Day 20, before rising sharply to adult levels (approximately 800 pg) between Days 20 and 30. The pituitary FSH content increased over the first 10 days of life to reach a peak of about 5000 ng, before declining to the adult value of about 2000 ng by Day 30, whilst the plasma FSH concentration was high in the first 10 days, but fell to adult levels over the next 20 days. Pituitary LH content increased significantly between Days 5 and 10 to reach the adult level of about 600 ng. Hypothalamic GnRH was undetectable at all ages in hypogonadal mice, but the pituitary content of FSH and LH had risen to the attenuated mutant adult value by Day 15, and unlike normals, plasma FSH concentrations were not elevated during the neonatal period. These results suggest that minimal gonadotrophic stimulation of the ovary from birth has no effect on the total number of follicles but reduces the number of growing follicles and prevents follicle growth beyond the early antral stage. Gonadotrophins therefore appear to have a role in the initiation and continuance of follicle growth in the adult mouse.     

人乳头瘤病毒16型E6和E7基因及其突变体转化活性的研究

为筛选出可用于研制HPV治疗性疫苗的HPV16型E6和E7基因突变体,故将HPV16型原型株(德国株)E6和E7基因及其各种突变体分别转染Balb/c3T3细胞,观察转染后的细胞在软琼脂培养中的集落形成能力和在裸鼠体内的成瘤能力.结果表明,单独转染和共转染HPV16野生型E6和E7基因的Balb/c3T3细胞系,在软琼脂中呈集落样生长,并在裸鼠体内成瘤;而转染E6基因突变体mE6(50G)、E7基因的两种突变体mE7-1(24G26G)和mE7-3(24G26G67R)以及共转染mE6和mE7-1的Balb/c3T3细胞,在软琼脂培养中极少形成集落,也不能在裸鼠体内成瘤.提示经结构改造后的HPV16 E6和E7基因已失去了对Balb/c3T3细胞的转化活性,而保留了免疫原性,可用于HPV16相关肿瘤治疗性疫苗的构建.     

The COW1 locus of arabidopsis acts after RHD2, and in parallel with RHD3 and TIP1, to determine the shape, rate of elongation, and number of root hairs produced from each site of hair formation.

Two recessive mutant alleles at CAN OF WORMS1 (COW1), a new locus involved in root hair morphogenesis, have been identified in Arabidopsis thaliana L. Heynh. Root hairs on Cow1- mutants are short and wide and occasionally formed as pairs at a single site of hair formation. The COW1 locus maps to chromosome 4. Root hairs on Cow1- plants form in the usual positions, suggesting that the phenotype is not the result of abnormal positional signals. Root hairs on Cow1- roots begin hair formation normally, forming a small bulge, or root hair initiation site, of normal size and shape and in the usual position on the hair-forming cell. However, when Cow1- root hairs start to elongate by tip growth, abnormalities in the shape and elongation rate of the hairs become apparent. Genetic evidence from double-mutant analysis of cow1-1 and other loci involved in root hair development supports our conclusion that COW1 is required during root hair elongation.     

A class I ADP-ribosylation factor GTPase-activating protein is critical for maintaining directional root hair growth in Arabidopsis

Membrane trafficking and cytoskeletal dynamics are important cellular processes that drive tip growth in root hairs. These processes interact with a multitude of signaling pathways that allow for the efficient transfer of information to specify the direction in which tip growth occurs. Here, we show that AGD1, a class I ADP ribosylation factor GTPase-activating protein, is important for maintaining straight growth in Arabidopsis (Arabidopsis thaliana) root hairs, since mutations in the AGD1 gene resulted in wavy root hair growth. Live cell imaging of growing agd1 root hairs revealed bundles of endoplasmic microtubules and actin filaments extending into the extreme tip. The wavy phenotype and pattern of cytoskeletal distribution in root hairs of agd1 partially resembled that of mutants in an armadillo repeat-containing kinesin (ARK1). Root hairs of double agd1 ark1 mutants were more severely deformed compared with single mutants. Organelle trafficking as revealed by a fluorescent Golgi marker was slightly inhibited, and Golgi stacks frequently protruded into the extreme root hair apex of agd1 mutants. Transient expression of green fluorescent protein-AGD1 in tobacco (Nicotiana tabacum) epidermal cells labeled punctate bodies that partially colocalized with the endocytic marker FM4-64, while ARK1-yellow fluorescent protein associated with microtubules. Brefeldin A rescued the phenotype of agd1, indicating that the altered activity of an AGD1-dependent ADP ribosylation factor contributes to the defective growth, organelle trafficking, and cytoskeletal organization of agd1 root hairs. We propose that AGD1, a regulator of membrane trafficking, and ARK1, a microtubule motor, are components of converging signaling pathways that affect cytoskeletal organization to specify growth orientation in Arabidopsis root hairs.     

Stimulation of ectodermal organ development by Ectodysplasin-A1

Organs developing as ectodermal appendages share similar early morphogenesis and molecular mechanisms. Ectodysplasin, a signaling molecule belonging to the tumor necrosis factor family, and its receptor Edar are required for normal development of several ectodermal organs in humans and mice. We have overexpressed two splice forms of ectodysplasin, Eda-A1 and Eda-A2, binding to Edar and another TNF receptor, Xedar, respectively, under the keratin 14 (K14) promoter in the ectoderm of transgenic mice. Eda-A2 overexpression did not cause a detectable phenotype. On the contrary, overexpression of Eda-A1 resulted in alterations in a variety of ectodermal organs, most notably in extra organs. Hair development was initiated continuously from E14 until birth, and in addition, the transgenic mice had supernumerary teeth and mammary glands, phenotypes not reported previously in transgenic mice. Also, hair composition and structure was abnormal, and the cycling of hairs was altered so that the growth phase (anagen) was prolonged. Both hairs and nails grew longer than normal. Molar teeth were of abnormal shape, and enamel formation was severely disturbed in incisors. Furthermore, sweat gland function was stimulated and sebaceous glands were enlarged. We conclude that ectodysplasin-Edar signaling has several roles in ectodermal organ development controlling their initiation, as well as morphogenesis and differentiation.     

G-protein complex mutants are hypersensitive to abscisic acid regulation of germination and postgermination development

Abscisic acid (ABA) plays regulatory roles in a host of physiological processes throughout plant growth and development. Seed germination, early seedling development, stomatal guard cell functions, and acclimation to adverse environmental conditions are key processes regulated by ABA. Recent evidence suggests that signaling processes in both seeds and guard cells involve heterotrimeric G proteins. To assess new roles for the Arabidopsis (Arabidopsis thaliana) Galpha subunit (GPA1), the Gbeta subunit (AGB1), and the candidate G-protein-coupled receptor (GCR1) in ABA signaling during germination and early seedling development, we utilized knockout mutants lacking one or more of these components. Our data show that GPA1, AGB1, and GCR1 each negatively regulates ABA signaling in seed germination and early seedling development. Plants lacking AGB1 have greater ABA hypersensitivity than plants lacking GPA1, suggesting that AGB1 is the predominant regulator of ABA signaling and that GPA1 affects the efficacy of AGB1 execution. GCR1 acts upstream of GPA1 and AGB1 for ABA signaling pathways during germination and early seedling development: gcr1 gpa1 double mutants exhibit a gpa1 phenotype and agb1 gcr1 and agb1 gcr1 gpa1 mutants exhibit an agb1 phenotype. Contrary to the scenario in guard cells, where GCR1 and GPA1 have opposite effects on ABA signaling during stomatal opening, GCR1 acts in concert with GPA1 and AGB1 in ABA signaling during germination and early seedling development. Thus, cell- and tissue-specific functional interaction in response to a given signal such as ABA may determine the distinct pathways regulated by the individual members of the G-protein complex.     

The efficiency of Arabidopsis thaliana (Brassicaceae) root hairs in phosphorus acquisition

Arabidopsis thaliana root hairs grow longer and denser in response to low-phosphorus availability. In addition, plants with the root hair response acquire more phosphorus than mutants that have root hairs that do not respond to phosphorus limiting conditions. The purpose of this experiment was to determine the efficiency of root hairs in phosphorus acquisition at high- and low-phosphorus availability. Root hair growth, root growth, root respiration, plant phosphorus uptake, and plant phosphorus content of 3-wk-old wild-type Arabidopsis (WS) were compared to two root hair mutants (rhd6 and rhd2) under high (54 mmol/m) and low (0.4 mmol/m) phosphorus availability. A cost-benefit analysis was constructed from the measurements to determine root hair efficiency. Under high-phosphorus availability, root hairs did not have an effect on any of the parameters measured. Under low-phosphorus availability, wild-type Arabidopsis had greater total root surface area, shoot biomass, phosphorus per root length, and specific phosphorus uptake. The cost-benefit analysis shows that under low phosphorus, wild-type roots acquire more phosphorus for every unit of carbon respired or unit of phosphorus invested into the roots than the mutants. We conclude that the response of root hairs to low-phosphorus availability is an efficient strategy for phosphorus acquisition.     

SCD1 is required for cytokinesis and polarized cell expansion in Arabidopsis thaliana [corrected

In the leaf epidermis, guard mother cells undergo a stereotyped symmetric division to form the guard cells of stomata. We have identified a temperature-sensitive Arabidopsis mutant, stomatal cytokinesis-defective 1-1 (scd1-1), which affects this specialized division. At the non-permissive temperature, 22 degrees C, defective scd1-1 guard cells are binucleate, and the formation of their ventral cell walls is incomplete. Cytokinesis was also disrupted in other types of epidermal cells such as pavement cells. Further phenotypic analysis of scd1-1 indicated a role for SCD1 in seedling growth, root elongation and flower morphogenesis. More severe scd1 T-DNA insertion alleles (scd1-2 and scd1-3) markedly affect polar cell expansion, most notably in trichomes and root hairs. SCD1 is a unique gene in Arabidopsis that encodes a protein related to animal proteins that regulate intracellular protein transport and/or mitogen-activated protein kinase signaling pathways. Consistent with a role for SCD1 in membrane trafficking, secretory vesicles were found to accumulate in cytokinesis-defective scd1 cells. In addition the scd1 mutant phenotype was enhanced by low doses of inhibitors of cell plate consolidation and vesicle secretion. We propose that SCD1 functions in polarized vesicle trafficking during plant cytokinesis and cell expansion.     

Growth and development of Gymnophalloides seoi in immunocompetent and immunosuppressed C3H/HeN mice

The growth and development of Gymnophalloides seoi were studied in C3H/HeN mice and effects of immunosuppression of the host on the worm development were observed. Two hundred metacercariae of G. seoi were orally administered to each mouse, and worms were recovered on days 1, 3, 5, 7, 14 and 21 post-infection (PI). The worm recovery rate was significantly higher in immunosuppressed (ImSP) mice than in immunocompetent (ImCT) mice except on days 1 and 3 PI. The worms attained sexual maturity by day 3 PI with eggs in the uterus, and worm dimensions and the number of uterine eggs continuously increased until day 14 PI in ImSP mice. Worms recovered from ImSP mice were significantly larger in size than those from ImCT mice on days 1 and 3 PI, and the number of uterine eggs was significantly larger in ImSP mice on days 5 and 7 PI. Genital organs such as the ovary, testes, and vitellaria, that were already developed in the metacercarial stage, grew a little in size until day 14 PI. The results show that the C3H/HeN mouse is, though not excellent, a suitable laboratory host for G. seoi.     

Cellular Distribution of Gangliosides in the Developing Mouse Cerebellum: Analysis Using the Staggerer Mutant

The distribution of cerebellar gangliosides was studied in staggerer (sg/sg) mutant mice, where the majority of granule cells die after completing their migration across the molecular layer. In addition, the external granule cell layer in sg/sg mice persists longer than in normal mice. Moreover, in the sg/sg cerebellum, Purkinje cells are significantly reduced in number, and almost none have tertiary branchlet spines. The loss of Purkinje cells and granule cells in sg/sg mice is accompanied by an early-onset reactive gliosis that continues through adulthood. By correlating changes in ganglioside composition with the well-documented histological events of cerebellar development in normal and sg/sg mice, we obtained strong evidence for a nonrandom cellular distribution of gangliosides. The sharpest reduction in the GD1a content of sg/sg cerebellum occurred after 15 days of age, coincident with granule cell loss. GT1a, on the other hand, was significantly reduced from 15 through 150 days in the sg/sg mice. GD3 is a major ganglioside of the undifferentiated granule cell, but it becomes rapidly displaced by the more complex gangliosides with the onset of granule cell maturation. In the sg/sg mice, GD3 persisted at abnormally high levels from 15 to 28 days and then accumulated through adulthood. These findings, and those from other cerebellar mouse mutants, suggest that GD1a is enriched in granule cells and that GT1a is enriched in Purkinje cells. Our findings also suggest that GT1a is more concentrated in branchlet spines than in other regions of the Purkinje cell membrane. GT1b appears to be enriched in both granule cells and Purkinje cells, whereas GM1 appears to be enriched in myelin. Furthermore, the apparent persistence of the embryonic ganglioside GD3 in sg/sg mice results from an early-onset reactive gliosis, together with a partial retardation in granule cell maturation. The accumulation of GD3 beyond 28 days reflects the continued accretion of GD3 in reactive glia.     

Myelin Basic Protein Deposition in the Optic and Sciatic Nerves of Dysmyelinating Mutants Quaking, Jimpy, Trembler, MLD, and Shiverer During Development

An ontogenetic survey of the basic protein of myelin, common to both central and peripheral nervous systems, was carried out on normal C57Bl and five dysmyelinating mutant mice. Myelin basic protein (MBP) was quantified by radioimmunoassay in the optic and sciatic nerves of mice from birth to adult stages, giving special attention to the premyelinating and early myelination periods. In the optic nerves of normal mice, MBP was already detectable at birth but the active period of myelin deposition was shown to occur after day 10 postnatal. The timing and rate of accumulation of MBP were normal in Trembler. In contrast, they were abnormal in the other mutants. In the quaking mouse, the active period of MBP deposition was delayed, and its final concentration represented no more than 12% of normal in the adult. No active period of MBP deposition was observed in the other mutants. In the jimpy mouse, a slow accumulation of MBP resulted in a final concentration reaching 2% of the normal value at 25 days. In mild and shiverer mice, the MBP was hardly detectable. In the sciatic nerves of normal mice, the active period of MBP deposition occurred between days 3 and 12 postnatal. No substantial changes occurred in the period of 2 months--2 years.(ABSTRACT TRUNCATED AT 250 WORDS)