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It is suggested that growth factors support the process of maturation and differentiation in the mammalian oviduct. Fibroblast growth factors (FGF) and insulin-like growth factors (IGF) are possible influences on these processes. The present study describes for the first time the expression of FGF-1 and -2 and their receptors as well as IGF-1 and -2 and the corresponding IGF receptor type 1 in the oviduct of the New World monkey Callithrix jacchus. Because of the limited RNA yields from oviducts, reverse transcription-polymerase chain reaction (RT-PCR) was performed to estimate expression levels. Expression patterns were found to be similar for all examined growth factors and receptors: the highest mRNA contents were obtained at the late proliferative and early to midsecretory phases, compared with lower levels during the early proliferative phase. Elevated amounts of these RNAs were correlated with high serum estradiol but not with progesterone concentrations. Each PCR product showed a high degree of homology (> 92%) to the known human sequences. Immunohistochemical analysis indicated greater specific staining for FGF-1 and -2 and IGF-1 before ovulation on the luminal epithelial surface of marmoset oviducts in comparison to the other cycle phases. Differences in staining intensity were not observed between the ampulla and isthmus. In summary, the marmoset oviduct expresses all components of functional FGF and IGF systems, thus suggesting auto-/paracrine effects of these growth factors within the primate oviduct, possibly under the control of estrogenic hormones.

It is now widely accepted that the mammary gland is under interconnected hormonal and local control. Growth factors are involved in the intercellular signalling of the gland. Our aim was the detection of transforming growth factors alpha (TGF-alpha) and beta 1 (TGF-beta 1) messenger RNA during mammogenesis, lactogenesis, galactopoiesis and involution in the bovine mammary gland (total n = 27). During these stages the RNA was assessed by means of ribonuclease protection assay and reverse transcription-polymerase chain reaction (RT-PCR). To study possible influences of oestrogen, progesterone and prolactin on growth factor expression, mammary RNA was obtained from heifers after induced mammogenesis and lactogenesis, with and without additional prolactin inhibition (total n = 20). Very low levels of TGF-alpha and TGF-beta 1 expression were detected during lactogenesis and galactopoiesis, increasing levels during mammogenesis of primigravid heifers, and highest levels during mammogenesis of virgin heifers and during involution. TGF-alpha expression after induced mammogenesis was greater than after induced lactogenesis or physiological mammogenesis during pregnancy. Furthermore, TGF-alpha mRNA contents increased after prolactin inhibition. TGF-beta 1 expression was almost equal after induced mammogenesis and lactogenesis, but greater than during the physiological mammogenesis and lactogenesis. In conclusion, it can be assumed that growth promoting TGF-alpha and growth inhibiting TGF-beta 1 are co-expressed in the bovine mammary gland. Higher mRNA contents of both factors during mammogenesis and involution may indicate autocrine or paracrine functions for these growth factors during proliferation and reorganisation of the mammary tissue.

The aim of this study was to determine whether the stage of the oestrous cycle (day 1, n = 5; day 6, n = 5; day 12, n = 3 gilts) has an influence on the expression and activity of epidermal growth factor receptor (EGF-R) in the pig oviduct and uterus. Histochemistry, cross-linking of 125I-labelled EGF to isolated oviductal and endometrial membranes or on cryostat sections, and EGF-R binding assay were used to demonstrate the presence of the EGF-R in a qualitative and quantitative manner. The bioactivity of the EGF-R in the oviduct was estimated by means of a protein tyrosine kinase activity assay. This study suggests that EGF-R is widely distributed both in glandular and stromal cells of the endometrium and in epithelial cells of the oviduct in pigs. The concentrations of EGF-R were higher in oviductal membranes on day 1 (22.4 +/- 8.7 fmol mg-1 protein) in comparison with day 6 (11.0 +/- 0.42 fmol mg-1 protein; P < 0.05), but not on day 12 (16.0 +/- 2.9 fmol mg-1 protein). The concentrations dropped similarly in the endometrium (day 1: 66.8 +/- 16.4 fmol mg-1 protein; day 6: 39.1 +/- 3.4 fmol mg-1 protein (P < 0.05); day 12: 38.0 +/- 14.6 fmol mg-1 protein). The dissociation constant (Kd) showed the same pattern. These data were supported by cross-linking of 125I-labelled EGF to a 170 kDa membrane protein representing the EGF-R. In contrast to day 6 and 12 of the cycle, a significantly (P < 0.05) higher endogenous protein tyrosine kinase activity was observed on day 1. In summary, changes in concentrations and functional status of the EGF-R may play a significant role in the cascade of cellular events in oviductal and endometrial tissues.

It is known that insulin-like growth-factor I (IGF-I) promotes early embryonic development from the morula to the blastocyst stage in rabbits (28). Therefore we used autoradiography to investigate whether IGF-I binds to preimplantation embryos and its coats. From Day 3 after mating onwards, a clear binding of IGF-I to the embryos was observed. There was no difference in binding to the embryoblast or trophoblast cells. Using ligand blot, several IGF-binding proteins (IGFBP; 31 kDa, 33 kDa, 36 kDa, three overlapping bands at 40 to 55 kDa) were obvious in the embryoblast and trophoblast. A 120 to 130 kDa protein was observed exclusively in the embryoblast. Significant binding of (125)I IGF-I to the coats of embryos older than 3 d was detected, and IGF-I was bound via a 38 kDa protein, as detected by ligand blot. To investigate the origin of this protein, the patterns of IGFBP were determined in the oviductal and uterine fluids of pregnant animals (Days 0 to 6). The following binding proteins were observed regularly in the oviductal and uterine flushings: 28 kDa, 32 kDa and 3 overlapping bands in the area of 40 to 55 kDa. In the oviduct the main IGF binding protein was the 32 kDa band (38.7% to 45.9%), while in the uterus it was the 3 overlapping bands at 40 to 55 kDa (42.5% to 24.1%). Because IGF-I is produced in the oviduct and uterus (27), IGFBPs are found in oviductal and uterine fluids, IGF-I is stored in the coats, IGF-I binds to preimplantation embryos and IGF-I promotes early embryonic development (28), the IGF system seams to have a function in the maternal-embryonic interaction.

The heparin-binding acidic and basic fibroblast growth factors (aFGF, bFGF) and their receptors in the bovine oviduct are described. By means of western blot analysis one 18 kDa aFGF and two bFGF proteins (16 and 18 kDa, respectively) were detected in oviductal flushings. Different concentrations of these two growth factors could be measured in oviductal flushings during the oestrous cycle: concentrations of aFGF protein were significantly higher at ovulation (mean +/- SEM; 5.3 +/- 0.5 ng ml-1) than during the luteal phase (3.0 +/- 0.3 ng ml-1); concentrations of bFGF were higher at the preovulatory stage (3.5 +/- 0.7 ng ml-1) than at the post-ovulatory stage (1.3 +/- 0.15 ng ml-1). Immunohistochemical studies using a/bFGF-specific antibodies indicated that these growth factors were localized mainly in oviduct epithelial cells. The sequence of the bovine FGF receptor (FGFR) was partly determined. Quantification of mRNAs by an RNase-protection assay (RPA) showed that expression of aFGF and bFGF was different during the oestrous cycle, indicating that the regulation of aFGF is separate from that of bFGF. Only mRNA encoding bFGF and FGFR could be detected in cumulus-oocyte complexes by reverse transcription PCR. In summary, the components of the FGF system were found in the bovine oviduct suggesting an autocrine or paracrine regulation involving oviduct cells and cumulus-oocyte complexes.

In this communication we approach the events leading to fertilization in mammals by examining the triangle of egg, sperm and oviductal cell taking account of the local physiology and focussing on auto/paracrine interactions. The expression of growth factors and extra-cellular matrix (ECM)-components in bovine ovarian granulosa- and theca-cells, the oocyte-cumulus complex (OOC) and oviductal epithelium, as well as some of the corresponding secreted proteins can be detected through the estrous cycle. Components of the insulin-like (IGF), fibroblast (FGF) and transforming (TGF) growth factor systems, and also metalloproteinase 1 (MMP1) and urokinase (uPA) are found to be modulated in these cells prior to fertilization. Different expression levels between the cell types are found, each representative of a specific reaction window within that particular stage of the cycle. Our findings support the concept that most of the observed tissue in the reproductive tract is dependent upon on the effects of gonadotropins or steroids, but that the fine-regulation is conveyed by, for example, growth factors and ECM-components. We suggest a sophisticated, auto/paracrine and species-specific crosstalk of growth factors and ECM components between the different cell types involved, enabling fertilization and development of the embryo at the right time and in the right location.

A radioactive (32P) and nonradioactive (digoxigenin) ribonuclease protection assay (RPA) has been developed to detect mRNAs of housekeeping proteins and growth factors. A modification of polyacrylamide gel electrophoresis (PAGE) to simplify RPA is described. Both Cleangels (Pharmacia) and laboratory-cast polyacrylamide gels, in a denaturing, horizontal electrophoresis system, were used. The amount of toxic chemicals and waste was reduced, in comparison with sequencing gels normally used for RPA. The protected RNA fragments were shown to be well-separated, with sufficient sensitivity in this modified, quick gel system.

The 13 kDa acidic seminal fluid protein (aSFP) is a major component of bovine semen exerting growth factor-like activity. The influence of the pure protein on sperm viability was observed by evaluating sperm motility using computer-assisted semen analysis. Furthermore, mitochondrial dehydrogenase activity as a parameter of sperm metabolism and the integrity of sperm membranes using a metal catalyzed lipid peroxidation assay were measured. Over a wide physiological range (0.003 to 4 g/l) aSFP did not influence motility and average-path velocity of sperm, but at the highest concentration (6 g/l) a significant reduction in motility could be observed. Mitochondrial activity was significantly stimulated at medium concentrations (0.125 to 2 g/l), whereas a 40% suppression was observed at maximum levels (4 g/l). A dose-dependent inhibition of lipid peroxidation could be demonstrated for medium and high concentrations of aSFP (0.125 to 4 g/l). Compared with other reducing agents, aSFP showed the highest potency in preventing oxidative stress. Such effects might be explained by the remarkable redox behavior of the protein. We suggest that in the bull aSFP may play a role in the regulation of sperm metabolism and the protection of sperm membranes from oxidative damage.

Differentiation between Carabus species (ground beetle) and subspecies is difficult, although there have been extensive studies. To address this problem we have applied PCR in combination with SSCP analysis focussing on the evolutionally conservative ubiquitin gene to elaborate a new approach to molecular differentiation between species. We report that Carabidae possess an ubiquitin gene and that its gene has a multimeric structure. Differential SSCP analysis was performed with the monomeric form of the gene to generate a clear SSCP pattern. Such PCR/SSCP resulted in reproducible patterns throughout our experiments. Comparing different Carabus species (Carabus granulatus, C. irregularis, C. violaceus and C. auronitens) we could observe clear interspecies differences but no differences between genders. Some species showed some remarkable differences between the individuals. We suggest that the ubiquitin PCR-SSCP technique might be an additional tool for the differentiation of ground beetles.

Acidic seminal fluid protein (aSFP, 12.9 kDa), a major protein of bull seminal plasma, belongs to the spermadhesin protein family. Boar spermadhesins become bound to the sperm head's surface at ejaculation and are thought to play a role as capacitation factors and/or in gamete recognition and binding. Here, we have investigated the topographical distribution and fate of bovine spermadhesin aSFP during sperm capacitation in order to assess whether aSFP could be involved in similar aspects of the fertilization process as its boar homologous proteins. 5.7 +/- 2.1 x 10(6) molecules/spermatozoa were quantitated on the surface of fresh ejaculated and washed sperm. The binding site of aSFP was restricted to a thin coat at the apical part of the acrosomal cap. The amount of aSFP in swim-up sperm was 1.8 +/- 1.0 x 10(6) molecules/spermatozoa, but decreased dramatically to 22 +/- 10 x 10(3) and to undetectable levels after incubation of sperm for 1.5 h and 18 h, respectively, in capacitation medium. This indicates that the bull spermatozoa surface may be completely depleted of spermadhesin aSFP before spermatozoa reach the surroundings of the investing egg. Therefore, our results suggest that aSFP may act as a decapacitation factor on bull spermatozoa rather than as a zona pellucida binding molecule.

Acidic seminal fluid protein (aSFP) is a major 13 kDa protein isolated from bull seminal plasma and characterized as a new growth factor which stimulates in vitro cell division and progesterone secretion by ovarian cells. Here, we establish that the four cysteines of oxidized aSFP form two disulfide bridges between nearest-neighbour residues. This pattern is conserved in boar spermadhesins, with which aSFP shares up to 50% amino acid sequence identity, and other proteins of the recently identified CUB domain family. Using isoelectric focusing in combination with sulfhydryl group-specific blotting, the three forms of aSFP were identified as completely oxidized (pI 4.7), partly reduced (pI 4.8) and fully reduced at pI 5.1. These results indicate that native aSFP possesses two pairs of cysteine residues of different reactivity. The observation that aSFP can protect sperm from oxidative damage might be explained by its reduction/oxidation behaviour.

Somatotropin and FSH act synergystically on insulin-like growth factor-I (IGF-I) synthesis in ovarian follicles; IGF-I regulates several granulosa cell specific functions and may thereby be beneficial in bovine superovulation. In a series of 3 experiments we investigated the effects of recombinant bovine somatotropin (rBST) on several parameters of the superovulatory response in dairy cows. A total of 81 Holstein Friesian crossbred dairy cows received either 640 mg rBST or the vehicle (controls) on Day 4 or 13 of the superovulation schedule. Superovulation was induced with 2500 IU PMSG on Day 9. The cows were artificially inseminated on Day 13. In Experiment 1, on Days 4, 8, 11, 13 and 17 4 to 5 animals each were slaughtered to obtain follicular fluid, endometrium and plasma. The rBST application increased IGF-I contents in plasma and follicular fluid on Days 8, 11 and 13 (P<0.05) in the treated cows when compared with that of the controls. Plasma and follicular IGF-I contents were correlated closely (rBST: r=0.90, n=10; control: r=0.94, n=9). The number of antral follicles increased following rBST treatment, and on the day of artificial insemination (AI) twice as many follicles>4 mm were counted in the rBST treated animals than in the control group. In Experiment 2, the flushing of 38 donors on Day 7 after AI resulted in more transferable embryos in the rBST group than in the control group (4.2+/-1.0 vs 2.5+/-0.7; P<0.05). In contrast, in Experiment 3 involving 21 animals when rBST was administered at the time of AI the superovulation response was not altered. It is concluded that rBST increases follicular and plasma IGF-I contents and thereby has profound effects on follicular and early embryonic development.

Insulin-like growth factors 1 and 2 (IGF-1 and 2), oxytocin, progesterone, estradiol and ubiquitin were measured in bovine follicle-lutein-cysts and in follicular fluid after the classification of ovarian follicles by size (Class I = <4 mm; Class II = 5-8 mm; Class III = 9-12 mm; Class IV = preovulatory; Class V = cystic). It was found that IGF-1 concentrations increased during growth from 280 ng/ml in small follicles to 489 ng/ml in preovulatory follicles; IGF-2 appeared to remain constant in follicular fluid and in cysts (275 ng/ml). Oxytocin values were low in Class I, II and III follicles (30 pg/ml) but increased in preovulatory and cystic follicles (75 pg/ml). Estradiol increased significantly only in preovulatory follicles. Ubiquitin, a protein reflecting cellular replicative activity, could be found in bovine follicular fluid in high concentrations: 1.6 mug/ml in Class I,II and III follicles with the highest amounts in preovulatory follicles (2.3 mug/ml). In contrast with normal follicles, cysts were found to have a minimal concentration of ubiquitin (0.3 mug/ml). Progesterone levels were 5 times higher in cysts (325 ng/ml) and IGF-1 concentrations were markedly higher in cystic follicles (881 ng/ml) than in the other follicles. Simultaneously, maximum gene expression for IGF-1 was found in granulosa/lutein cells of cystic follicles (Class V), suggesting de novo synthesis of IGF-1. Between the different follicle classes progesterone, oxytocin and IGF-1 concentrations correlated positively (r=0.82). Hormonal levels in follicle-lutein-cysts indicated an arrested stage of insufficient luteinization as a possible result from the premature release of LH or from the release of amounts of LH inadequate to cause ovulation.

The concentration of the new bioactive acetic seminal fluid protein (aSFP) was determined in body fluids of bulls. An aSFP-specific radioimmunoassay was elaborated and established for routine measurement. No crossreaction of the aSFP antibody was found with other seminal plasma proteins and known growth factors. The 14 kDa aSFP was detected in secretions of ampulla and seminal vesicles by immunoblot analysis, but not in testis, epididymis or blood. Large quantities of aSFP were measured by radioimmunoassay in the fluid from the ampulla (2.6 +/- 0.3 mg ml-1) and seminal vesicles (3.0 +/- 0.4 mg ml-1). Immunohistochemistry techniques demonstrated that aSFP was localized mainly in the secretory epithelium of ampulla and seminal vesicles. Large amounts of aSFP (4.0 +/- 0.4 mg ml-1) were present in seminal plasma of bulls within a range of 1-7 mg ml-1, but aSFP could not be found on membranes of spermatozoa. Concentrations vary considerably among individuals, suggesting that aSFP may have a role in bovine reproduction.

A cDNA expression library in lambda gt11 prepared from cDNA derived of seminal vesicle tissue was screened by means of monospecific rabbit anti-aSFP IgG. The sequence of clone pTF21, containing an insert of 668 bp comprised an open reading frame from position 7 to 411 terminated by two stop codons. From this sequence a protein of 134 amino acid residues can be deduced. The mature aSFP was preceded by a signal peptide of 20 amino acids length. The protein sequence contains no signal for N-glycosylation. The molecular weight calculated from the amino acid sequence is 12922 Da. The start codon ATG is part of the sequence AAGATGA which fulfills the criteria of an initiation consensus sequence. The coding region was followed by 257bp of the complete 3'-untranslated region (3'UTR). A putative polyadenylation signal AATAAT, although not of the standard type, is observed at position 650. According to Northern analysis, aSFP mRNA is expressed in seminal vesicle tissue, ampulla and weakly in tissue of epididymis, but not in testis or other bovine tissue. aSFP is specified by a single copy gene. Attempts to detect homologies to known protein sequences were not successful.

A new acidic seminal fluid protein (aSFP) was purified from bovine seminal fluid, using anion exchange chromatography and FPLC on MonoQ. The purified aSFP displays a pI of 4.8 and an apparent molecular weight of 14 kDa. Homogeneity of aSFP was demonstrated by FPLC and SDS-polyacrylamide gel electrophoresis. Monospecific anti-aSFP IgGs were employed to characterize aSFP in bovine seminal plasma and seminal vesicle secretion by immuno blot analysis. Proteinchemical characterization of aSFP included amino acid analysis as well as determination of 23 amino acid residues of the N-terminal sequence of aSFP. According to this sequence, aSFP appears to represent a hitherto unknown protein. aSFP stimulated cell division and progesterone secretion of bovine granulosa cells in vitro in a potent and dose dependent manner. aSFP appears to be a potent growth factor with effects on ovarian granulosa cells.

The aim of this study was to monitor the changes of growth hormone (GH), insulin-like growth factor I (IGF-I) and insulin in the secretion of the bovine mammary gland from day 70 ante partum (AP) till 6 days post partum (PP) and during entire lactation period. For comparable reasons additional blood concentrations were evaluated. The association of IGF-I with its binding proteins in milk was analysed. In a further experiment the possible transfer of IGF-I and insulin into the peripheral circulation of calves was evaluated after application of an enriched and from content defined colostrum pool. The hormones were determined by RIA. Highest level of IGF-I and insulin in milk were found 2 weeks AP followed by a rapid decrease during the first milkings PP. Blood concentrations were much lower and decreased at that time. Striking differences were found in the distribution of bound and free IGF-I AP compared with the first milkings (colostrum) PP. Most of the IGF-I was in a free form (not associated with binding proteins) in colostrum which contrasted to the secretion AP or 4 days after parturition or during entire lactation. Application of a colostrum pool (4.62 mg/2 1 vs milk 0.042 mg/2 l) to calves 6 h after parturition did not increase peripheral blood levels of IGF-I in contrast to insulin. Local effects of the peptide hormones in colostrum to the mammary gland and intestinal tract of the calf are assumed.(ABSTRACT TRUNCATED AT 250 WORDS)

Concentrations of insulin-like growth factor 1 (IGF-1), insulin and growth hormone were measured in the secretion of the bovine mammary gland from day 70 ante partum until 6 d post partum. Highest levels were found during the last 2 weeks ante partum followed by a rapid decrease during the first milkings post partum. The association of IGF-1 with its binding proteins in milk was analysed and striking differences were found in the distribution of bound and free IGF-1. IGF-1 appeared mainly in the bound form (91%) at days 40-2 ante partum. Free IGF-1 preponderated in the first milkings post partum (73%) and changed again to about 85% in the bound form after day 4 post partum. A slightly acidic pH (6.3) of the secretion was correlated with high amounts of free IGF-1. Gel filtration experiments revealed a possible pH-dependent mechanism for the binding of IGF-1 to its binding proteins in milk.

The expression of IGF-I in bovine luteal tissue was demonstrated by parallel measurement of IGF-I tissue concentration and its mRNA; highest synthesis was observed during Days 12-17 of the cycle and the first months of pregnancy. Tissue levels of IGF-I increased from Days 1-5 to Days 12-17 of the cycle followed by a rapid decrease at luteolysis; there was a continuous decline from early pregnancy until Months 6-9. Microdialysis perfusion experiments with corpora lutea in vitro at Days 8-11 of the cycle revealed a major effect: release of progesterone and oxytocin were highly stimulated in a dose-dependent manner. We suggest that IGF-I could be important in regulating the function of the bovine corpus luteum and may act in an autocrine/paracrine way.

The relative levels of mRNAs for relaxin, prolactin, inhibin and oxytocin have been measured in porcine granulosa as well as luteal cells by hybridisation to single-stranded synthetic DNA. The likelihood of a paracrine function of oxytocin and prolactin in the porcine ovary was inferred from the in vitro effects of both hormones on progesterone secretion of ovarian cells. Both hormones were found to inhibit progesterone secretion of luteal cells. In contrast, only prolactin but not oxytocin stimulated progesterone secretion in granulosa cells.

A cDNA clone, pHGR81, encoding 358 amino-acid residues of the C-terminal region of human elongation factor 2 (EF-2), was isolated from a human ovarian granulosa cell cDNA library. The deduced amino-acid sequence of pHGR81, when compared with the known identical amino-acid sequences of hamster as well as rat EF-2 revealed a substitution of a glutamine by an alanine residue in the partially determined human sequence. The 15 amino-acid-residue sequence comprising the histidine-715, supposed to be of importance for the biological function of EF-2, is preserved in human EF-2. The coding region of the cDNA insert of pHGR81 displays a homology of 87% to hamster and of 88% to rat EF-2 cDNA. In Northern-transfer analysis, pHGR81 specifically hybridizes with an mRNA species of 3.1 kb.

A cDNA library derived from a particular fraction of mRNA of porcine corpus luteum was screened by hybrid-release. cDNA clone pCL208 selected an mRNA which, in cell-free translation, directed the synthesis of a major polypeptide of 28 kD. Sequence analysis of clone pCL208 revealed that the entire coding sequence contained three complete repeats and a fourth incomplete repeat of porcine ubiquitin, joined head-to-tail without any spacer peptide sequences. The ultimate ubiquitin molecule contained a Phe residue as a carboxy-terminal extension. The coding sequence terminated with the stop codon TAA followed by a short untranslated region, the polyadenylation signal AATAAA, and a tract of A residues. Northern analysis indicated the presence of two types of ubiquitin-specific mRNAs, i.e., 1100 and 2500 bp, in porcine corpus luteum.

In cell suspension cultures of Chenopodium rubrum maintained under photomixotrophic or photoautotrophic growth conditions the differentiation of chloroplasts is strictly blue-light-dependent. During this process of greening the steady-state concentration of mRNAs coding for plastid proteins increases rapidly in response to blue-light exposure as was determined by a dothybridization technique employing cloned DNA sequences complementary to these nuclear and plastid transcripts (light-harvesting chlorophyll a/b protein, rbcs, rbcl, psbA, atpB, atpE). Red light suppresses this response when applied at an advanced stage of chloroplast development. Indications are that blue-light dependency of chloroplast differentiation is a common feature of cultured plant cells irrespective of their metabolism. A DNA-protein complex with an active RNA polymerase ("transcriptionally active chromosome"; TAC) which specifically transcribes the plastid genes of its endogenous DNA has been isolated and purified from chloroplasts of light-grown cells. Quantitative analyses of these in-vitro transcripts show that the activity of TAC from cells grown in blue light prior to isolation is significantly higher than that of TAC from cells raised in red light under the same conditions. The results indicate that blue light enhances the transcription of plastid genes encoding prominent proteins. This response could account for the observed rise in transcript level in vivo.