Haploid Embryos Research Articles

Utilization of Reduced Haploid Vigor for Phenomic Discrimination of Haploid and Diploid Maize Seedlings

Core Ideas There are many potential benefits of incorporating embryo culture into a doubled haploid program. There is no known non‐transgenic method of selecting haploid embryos following embryo culture. Our goal was to establish a non‐transgenic haploid selection method following embryo culture. These methods allow early haploid selection based on differential root growth features. Potential benefits of incorporating embryo culture (EC) into a doubled haploid (DH) program, including shortening the breeding cycle and increasing chromosome doubling rates, make the laborious and tedious task of excising embryos worth the effort. Difficulties arise during embryo selection considering the marker gene R1‐nj, which is typically used in DH programs, is not expressed in early stages after pollination. Although transgenic approaches have been implemented to bypass this issue, there is so far no known non‐transgenic method of selecting haploid embryos. The findings of this study reveal methods of selecting haploid embryos that allow the possibility of incorporating EC into a DH program without using transgenic inducers. The best performing method involves a machine‐learning classifier, specifically a support vector machine, which uses primary root lengths and daily growth rates as traits for classification. Selection by this method can be achieved on the third day after germination. By this method, an average false negative rate of 2% and false positive rate of 9% was achieved. Therefore, the methods presented in this research allow efficient and non‐transgenic selection of haploid embryos that is simple and effective.

Generation of Xenopus Haploid, Triploid, and Hybrid Embryos.

Frog species of the genus Xenopus are widely used for studies of cell and developmental biology, and recent genome sequencing has revealed interesting phylogenetic relationships. Here we describe methods to generate haploid, triploid, and hybrid species starting from eggs and sperm of Xenopus laevis and Xenopus tropicalis that enable investigation of how genome size and content affect physiology at the organismal, cellular, and subcellular levels.

Influence of Maize Genotypes on Wheat Haploid Embryos Production in Maize Mediated Cross System

Influence of Maize Genotypes on Wheat Haploid Embryos Production in Maize Mediated Cross System

Modulation of autophagy and protease activities by small bioactive compounds to reduce cell death and improve stress-induced microspore embryogenesis initiation in rapeseed and barley

ABSTRACTMicrospore embryogenesis is a powerful biotechnological tool that is very useful in crop breeding for the rapid production of haploid and double-haploid embryos and plants. In this in vitro system, the haploid microspore is reprogrammed by the application of specific stress treatments. A high level of cell death after the stress is a major factor that greatly reduces embryogenesis yield at its initial stages. Autophagy is a degradation pathway that is present in all eukaryotes and plays key roles in a range of processes, including stress responses. Many proteases participate in autophagy and cell death; among them, cathepsins are the most abundant enzymes with a role in plant senescence and programmed cell death (PCD). Moreover, although plant genomes do not contain homologues of caspases, caspase 3-like activity (main executioner protease of animal cell death) has been detected in many plant PCD processes. Recent studies by our group in barley microspore cultures reported that the stress treatment required for inducing microspore embryogenesis (cold treatment), also produced reactive oxygen species (ROS) and cell death, concomitantly with the induction of autophagy, as well as cathepsin-like and caspase 3-like proteolytic activities. In the present study, we report new data on microspore embryogenesis of rapeseed that indicate, as in barley, activation of cell death and autophagy processes after the inductive stress. The results revealed that treatments modulating autophagy and proteases produced the same effect in the two plant systems, regardless of the stress applied, cold in barley or heat in rapeseed. Pharmacological treatments with small bioactive compounds that inhibit ROS, autophagy and specific cell death-proteases led to reduced cell death and an increased embryogenesis initiation rate in both, barley and rapeseed. Taken together, these findings open up new intervention pathways by modulating autophagy and proteases, which are very promising in terms of increasing the efficiency of in vitro microspore embryogenesis systems for biotechnological applications in crop breeding.

181 Equine androgenic embryos: ability of the equine sperm to develop in a heterospecific ooplasm

Androgenic haploid embryos were originally produced for the study of certain aspects of early embryo development. The generation of androgenic haploid embryos allows us to better understand the complementary parental contribution to embryonic development, and to examine the effects of haploid development on gene expression. Because mare oocytes for research are scarce, the generation of heterospecific androgenic embryos could be useful to study aspects of the biology of early embryo development, or to identify genes and their variations or mutations that are responsible for reproduction-related problems in mares and stallions, which is of interest for the breeding industry. Therefore, the aim of this work was to study the capability of equine sperm to induce embryonic development after injection into an enucleated oocyte from a different species. Porcine cumulus-oocyte complexes (COC) were obtained from abattoir ovaries and placed in 100-µL drops in vitro maturation (IVM) medium for 42h. Cumulus cells were removed with hyaluronidase and vortexing. Then, mature oocytes were subjected to intracytoplasmic sperm injection (ICSI) with stallion frozen-thawed semen (according to Rodriguez et al. 2015). Immediately after the last injection, the zona pellucida of injected oocytes was removed with protease treatment, the oocytes were treated with cytochalasin B, and the metaphase II enucleated with a 20-µm micropipette. Finally, embryos were placed in culture medium (SOF) in plates with the well-of-the-well (WOW) system. As control treatment, non-enucleated pig oocytes were injected with stallion (CE) and boar (CC) semen. At Day 4, embryos were evaluated for cleavage and number of blastomeres, and stained with Hoechst 33342 to verify the presence of DNA in each blastomere under the UV light. Embryos were stored for future PCR studies to validate the presence of equine DNA. Data were analysed by chi-squared test to compare the cleavage of both controls with the androgenic embryos. From a total of 53 androgenic haploid embryos, the cleavage rate was 62% (33/53). Embryos were cleaved in 2 to 4 cells in 72.7%, 5 to 8 cells in 18.2%, and 9+ cells in 9.1% at Day 4. Presence of DNA in all blastomeres was observed in 60.6% (20/33) of the androgenic haploid embryos, while 21.2% (7/33) of the embryos had 10 to 50% of blastomeres with DNA, and 18.6% (6/33) of the embryos did not have DNA in their blastomeres. The ICSI control embryos cleaved in 45.3% (34/75) and 64.9% (98/151) for groups CC and CE, respectively. Cleavage rates in control CE were significantly higher than those in control CC (P<0.004). No statistical difference was observed in the control groups versus androgenic embryos. This preliminary results showed that a heterospecific ooplasm can be successfully used to allow an equine sperm DNA to decondense and to develop, even in absence of the female counterpart. Using this method, copies of a single sperm DNA can be produced to potentially evaluate individual aspects of early embryo development concerning the male contribution. This is the first report of successful androgenic embryos using a heterospecific oocyte to create copies of a horse sperm DNA.

Weighted Correlation Network Analysis (WGCNA) of Japanese Flounder (Paralichthys olivaceus) Embryo Transcriptome Provides Crucial Gene Sets for Understanding Haploid Syndrome and Rescue by Diploidization

Artificial gynogenesis is of great research value in fish genetics and breeding technology. However, existing studies did not explain the mechanism of some interesting phenomena. Severe developmental defects in gynogenetic haploids can lead to death during hatching. After diploidization of chromosomes, gynogenetic diploids may dispense from the remarkable malformation and restore the viability, although the development time is longer and the survival rate is lower compared with normal diploids. The aim of this study was to reveal key mechanism in haploid syndrome of Japanese flounder, a commercially important marine teleost in East Asia. We measured genome-scale gene expression of flounder haploid, gynogenetic diploid and normal diploid embryos using RNA-Seq, constructed a module-centric co-expression network based on weighted correlation network analysis (WGCNA) and analyzed the biological functions of correlated modules. Module gene content analysis revealed that the formation of gynogenetic haploids was closely related to the abnormality of plasma proteins, and the up-regulation of p53 signaling pathway might rescue gynogenetic embryos from haploid syndrome via regulating cell cycle arrest, apoptosis and DNA repair. Moreover, normal diploid has more robust nervous system. This work provides novel insights into molecular mechanisms in haploid syndrome and the rescue process by gynogenetic diploidization.

The cellular phenotype of cytoplasmic incompatibility in Culex pipiens in the light of cidB diversity.

Wolbachia are maternally inherited endosymbiotic bacteria, widespread among arthropods thanks to host reproductive manipulations that increase their prevalence into host populations. The most commonly observed manipulation is cytoplasmic incompatibility (CI). CI leads to embryonic death in crosses between i) infected males and uninfected females and ii) individuals infected with incompatible Wolbachia strains. CI can be conceptualized as a toxin-antidote system where a toxin deposited by Wolbachia in the sperm would induce embryonic death unless countered by an antidote produced by Wolbachia present in the eggs. In Drosophila melanogaster, transgenic expression of Wolbachia effector cidB revealed its function of CI-inducing toxin. Moreover in Culex pipiens, the diversity of cidB variants present in wPip strains accounts for the diversity in crossing-types. We conducted cytological analyses to determine the CI mechanisms that lead to embryonic death in C. pipiens, and assess whether diversity in crossing-types could be based on variations in these mechanisms. We revealed that paternal chromatin condensation and segregation defects during the first embryonic division are always responsible for embryonic death. The strongest observed defects lead to an exclusion of the paternal chromatin from the first zygotic division, resulting in haploid embryos unable to hatch. The proportion of unhatched haploid embryos, developing with only maternal chromatin, which reflects the frequency of strong defects can be considered as a proxy of CI intensity at the cellular level. We thus studied the putative effect of variations in crossing types and cidB diversification on CI defects intensity. Incompatible crosses involving distinct wPip strains revealed that CI defects intensity depends on the Wolbachia strains hosted by the males and is linked to the diversity of cidB genes harbored in their genomes. These results support that, additionally to its implication in C. pipiens crossing type variability, cidB diversification also influences the strength of CI embryonic defects.

Intra-ooplasmic injection of a multiple number of sperm to induce androgenesis and polyploidy in the dojo loach Misgurnus anguillicaudatus (Teleostei: Cobitidae)

SummaryPolyspermy was initiated by microinjecting a multiple number of sperm into the activated and dechorionated eggs of dojo loach Misgurnus anguillicaudatus (Teleostei: Cobitidae). A 10-nl sperm suspension from an albino (recessive trait) male (105, 106, 107 or 108 sperm ml -1) was microinjected into eggs from a wild-type female. Although the rates of embryos developing into the blastula stage in the injection group at the highest sperm concentration were similar to that of the control group, the hatching rates of the injection group were much lower. A large proportion of embryos that developed from the injected eggs was haploid and were mosaics containing haploid cells. Most of the haploid and mosaic embryos inherited only paternally derived alleles in the microsatellite markers (i.e. androgenesis was initiated by injecting multiple sperm). In contrast, some haploid embryos contained both paternal and maternal alleles despite haploidy, suggesting that they were mosaics consisting of cells with either paternal or maternal inheritance. The injected eggs displayed diploid, hypotriploid and triploid cells, all of which included both maternally and paternally derived alleles. One albino tetraploid with only paternal alleles was also observed from the injected eggs. These results suggested that part of the sperm microinjected into the ooplasm should form a male pronucleus/pronuclei, which could develop by androgenesis or could fuse with the female pronucleus/pronuclei. Therefore, microinjection of multiple sperm should be considered a potential technique to induce androgenesis and polyploidy.

Obtaining of Winter Rye (Secale Cereale L. ssp. Cereale) Haploid Embryos through Hybridization with Maize (Zea Mays L.)

The aim of this study was to determine the effect of selected factors on rye (Secale cereale L.) haploid embryo production by the wide crossing method. The study was performed on fifteen winter rye genotypes. This is the first time for rye when besides the genotype, on the enlargement of ovaries and haploid embryo production, such factors as: type of auxin analogues 2,4-dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 4-amino-3,5,6-trichloropyridine-2-carboxylic acid (picloram), and the time between florets emasculation and pollination were investigated. All factors had a significant impact on rye ovary enlargement, however the haploid embryo formation depended only on rye genotype, not on kind of auxin and days between emasculation to pollination. In total, twenty one haploid embryos were formed by six genotypes of fifteen tested. On average, 13.86% (after 2,4-D treatment) to 20.05% (after dicamba treatment) enlarged ovaries per emasculated florets were obtained. Most of the ovaries enlarged when florets were pollinated 4 and 6 days after emasculation. Most of the haploid embryos formed when florets were pollinated 6 days after emasculation. The obtained haploid embryos did not germinate.

A novel next-generation sequencing-based aneuploidy screening technology: capturing single-nucleotide polymorphism data to reduce the transfer of polyploid and haploid embryos

A novel next-generation sequencing-based aneuploidy screening technology: capturing single-nucleotide polymorphism data to reduce the transfer of polyploid and haploid embryos

Culture of haploid blastocysts in FGF4 favors the derivation of epiblast stem cells with a primed epigenetic and transcriptional landscape

Pluripotent stem cells within the inner cell mass and epiblast of mammalian embryos have the capacity to form all lineages in the adult organism, while multipotent trophoblast stem (TS) cells derived from the trophectoderm are capable of differentiating into fetal lineages of the placenta. While mouse embryonic stem (ES) cells and epiblast stem cells (EpiSCs) exhibit distinct expression patterns and utilize distinct external signaling pathways for self-renewal, because mouse EpiSCs resemble human ES cells they are a useful model to investigate mechanisms of human ES cell self-renewal and differentiation. Recent studies have shown that haploid embryos and ES cells can be generated from chemically-activated unfertilized mouse oocytes. However, it is unclear whether EpiSCs or TS cells can be derived from haploid embryos. Here, we describe the derivation of EpiSCs from haploid blastocyst-stage embryos using culture conditions that promote TS cell self-renewal. Maternal (parthenogenetic/gynogenetic) EpiSCs (maEpiSCs) functionally and morphologically resemble conventional EpiSCs. Established maEpiSCs and conventional EpiSCs are diploid and exhibit a normal number of chromosomes. Moreover, global expression analyses and epigenomic profiling revealed that maEpiSCs and conventional EpiSCs exhibit similarly primed transcriptional programs and epigenetic profiles, respectively. Altogether, our results describe a useful experimental model to generate EpiSCs from haploid embryos, provide insight into self-renewal mechanisms of EpiSCs, and suggest that FGF4 is not sufficient to derive TS cells from haploid blastocyst-stage embryos.

The effect of genotype, media composition, pH and sugar concentrations on oat (Avena sativa L.) doubled haploid production through oat \xd7 maize crosses

Doubled haploid (DH) technology in oat has not reached the same stage as in other cereals leading to its application in plant breeding. The objective of this investigation was to increase the effectiveness of Avena sativa L. haploid embryo germination obtained by the distant crosses with maize. Developed embryos (obtained from 22 genotypes) were transferred on five germination media: MS (Murashige and Skoog, Physiol Plant 15:473–497, 1962) with 3% sucrose, pH 5.8 (control medium), and 190-2 supplemented with 6 and 9% maltose. The pH of 190-2 was adjusted to 5.5 and 6.0. Of all tested genotypes, 591 haploid embryos were obtained, almost half of them (279) germinated. The rate of haploid embryo germination induced on 190-2 was 6.92%, while in MS it was 3.25%. The sugar and its concentration significantly affected the germination of haploid embryos. The highest percentage of haploid embryo germination (9.11%) and DH lines production (1.64%) was achieved on 190-2 with 9% maltose and pH 6.0. All DH lines are incorporated to breeding programs for the development of new cultivars.

Efficient Parthenogenesis Induction and In Vitro Haploid Plant Regeneration in Cucumber (Cucumis sativus L.) Using Putrescine, Spermidine, and Cycocel

In this study, the effect of spraying mother plants with various levels of putrescine, spermidine, and cycocel (each at 0, 50, 500, and 5000 mg/l) were assessed on the frequency of haploid embryos produced from unfertilized ovaries and subsequent regeneration of derived embryos. Significantly higher haploid embryos were obtained when mother plants were sprayed with putrescine at 500 mg/l (5.2 embryos/fruit), spermidine at 50 mg/l (4.8 embryos/fruit), and cycocel at 50 mg/l (5.2 embryos/fruit) as compared to the control (without spraying, 3.2 embryos/fruit). However, embryogenesis induction was decreased drastically as the concentration of all the three compounds tested was increased and the lowest haploid embryos were observed when 5000 mg/l of spermidine (0.4 embryos/fruit) or cycocel (2.0 embryos/fruit) were applied. Only spermidine at 50 mg/l led to 100% regeneration into fully developed plantlets. The seed setting and size of fruits were also affected by polyamines and cycocel applications. Ploidy analysis using a flow cytometer indicated that all regenerated plantlets contain the gametic chromosome number (n = x = 7) of parental plants and the results of chromosome counting also confirmed the haploid nature of regenerated plantlets. It can be concluded that the induction of haploid embryogenesis from unfertilized ovaries after pollination with irradiated pollen and subsequent conversion of derived embryos into the plantlets could be improved in Cucumis sativus L. by applying appropriate levels of putrescine, spermidine, and cycocel.

Histone variant H3.3–mediated chromatin remodeling is essential for paternal genome activation in mouse preimplantation embryos

Derepression of chromatin-mediated transcriptional repression of paternal and maternal genomes is considered the first major step that initiates zygotic gene expression after fertilization. The histone variant H3.3 is present in both male and female gametes and is thought to be important for remodeling the paternal and maternal genomes for activation during both fertilization and embryogenesis. However, the underlying mechanisms remain poorly understood. Using our H3.3B-HA-tagged mouse model, engineered to report H3.3 expression in live animals and to distinguish different sources of H3.3 protein in embryos, we show here that sperm-derived H3.3 (sH3.3) protein is removed from the sperm genome shortly after fertilization and extruded from the zygotes via the second polar bodies (PBII) during embryogenesis. We also found that the maternal H3.3 (mH3.3) protein is incorporated into the paternal genome as early as 2 h postfertilization and is detectable in the paternal genome until the morula stage. Knockdown of maternal H3.3 resulted in compromised embryonic development both of fertilized embryos and of androgenetic haploid embryos. Furthermore, we report that mH3.3 depletion in oocytes impairs both activation of the Oct4 pluripotency marker gene and global de novo transcription from the paternal genome important for early embryonic development. Our results suggest that H3.3-mediated paternal chromatin remodeling is essential for the development of preimplantation embryos and the activation of the paternal genome during embryogenesis.

Improved Procedure for Induction of the Androgenetic Doubled Haploids in Zebrafish.

Androgenesis is useful for induction of doubled haploids from male genetic resources and contributes to the restoration of individuals from cryopreserved sperm. Here, we determined the suitable conditions for egg in vitro preservation and the suitable dose of UV irradiation for genetic inactivation of the egg nucleus, and established an improved procedure for induction of androgenetic-doubled haploids in zebrafish. The suitable solution for egg preservation was evaluated by the fertilization rate using different types of solutions or conditions. Hank's solution with 0.5% bovine serum albumin (pH8.0) was suitable for the preservation of zebrafish eggs. In addition, we discovered an improvement of fertilization rates by temporal preservation of ovulated eggs in the suitable solution. UV irradiation of eggs at 50-75 mJ/cm2 induced haploid embryos. Microsatellite genotyping using eight loci revealed the paternity and homozygosity of the putative androgenetic doubled haploids. The yield rate of androgenetic doubled haploids, which were induced by UV irradiation and heat shock, ranged from 0.4% to 10.7%.

Production and conversion of haploid embryos in chickpea (Cicer arietinum L.) anther cultures using high 2,4-D and silver nitrate containing media

Due to recalcitrant nature of chickpea (Cicer arietinum L.) to androgenesis, the production of double haploid plants has been only reported by Grewal et al. (Plant Cell Rep 28:1289–1299, 2009) using some physical stresses such as anther centrifugation and electrical shock. In the present study, we successfully obtained haploid plants from cultured anthers of two chickpea cultivars, Bivanij and Arman, using high 2,4-D and silver nitrate containing media without applying of these time and labor consuming stresses. For induction of androgenesis, different concentrations of 2, 4-D (0, 2, 5 and 10 mg/l) and silver nitrate (0, 5, 10, 15, 25 and 50 mg/l) were used in embryo development medium. In Bivanij cultivar, anther induction medium containing 10 mg/l 2,4-D and 15 mg/l silver nitrate produced the highest number of embryos (0.188) and regenerated plants (0.1) per each cultured anther, while the highest frequencies of embryos (0.1) and regenerated plants (0.075 and 0.063) were obtained from Arman cultivar when 10 mg/l 2,4-D was combined with 15 and 50 mg/l silver nitrate in anther culture medium, respectively. In second part of this study, different cold (4 °C for 4 and 7 days) and heat (30 °C for 10 days, 32 °C for 2 days and 35 °C for 8 h) pretreatments were applied on cultured anthers of Bivanij cultivar. Incubation of cultured anthers at 32 °C for 2 days significantly enhanced the rate of embryo formation up to 0.222 embryos per each anther, while the highest number of regenerated plants/anther (0.0332) was obtained when cold treated anthers at 4 °C for 7 days incubated at 30 °C for 10 days. Taken together, these results provide a good basis for large-scale generation of DH plants in this important legume species.

Effective Generation of Gynogenic Haploid Zebrafish Embryos Using Low Dosage of UV Rays.

The phenomenon of phenotype manifestation when the single allele in a haploid is affected is desirable for uncovering recessive mutations expeditiously in a diploid organism. However, experimentally generated haploids manifest extensive lethality and a cluster of non-specific developmental defects known as the haploid syndrome. This precludes the use of experimentally generated haploids for genetic screens due to an insufficient number of embryos for screening and the possibility of phenotypes due to the affected gene being masked by the haploid syndrome. We show here that gynogenic haploid zebrafish can be generated by irradiation of spermatozoa with a lower UV dosage than is currently used. This strategy results in reduced haploid lethality, incidence and severity of haploid syndrome. When viewed in the context of zebrafish as a genetically tractable model organism for forward and reverse genetic strategies, these results place zebrafish in a unique niche as a vertebrate in which haploid genetic screens for developmental phenotypes could be successfully attempted.

Production of doubled haploids in sugar beet (Beta vulgaris): an efficient method by a multivariate experiment

The present paper describes a detailed study of a highly efficient protocol to multiply the number of haploids in sugar beet production and subsequent chromosome doubling. The protocol involves an experiment investigating factorial interactions between cold pretreatment, seven genotypes of sugar beet, and kinetin to improve haploid embryo induction. In addition, the effects of color of ovules and flower bud position on haploid embryo induction were investigated. After subjecting the data to analysis of variance or Student’s t test (P < .05), the effect sizes of the independent variables were also estimated. Cold pretreatment was effective in stimulating the ovules. The haploid embryo induction rate for 1-week cold pretreated ovules (9.01%) was higher than that of freshly cultured ones (6.15%). In comparison with hormone-free medium (5.16%), the gynogenesis rate for the media supplemented with 0.05 or 0.5 mg L−l kinetin increased to 7.58 and 10.05%, respectively. The genotype responses were significantly different. Interactions of kinetin × cold pretreatment, genotype × hormonal treatment, genotype × cold pretreatment, and the three-way interaction were statistically significant. Moreover, the main effects of flower bud position, ovule color, and comma-form ovule on gynogenic response were significant. After investigating the effect of 5 g L−l colchicine for 3, 5, or 7 min on one genotype’s (SG2) specimens, all the haploid plantlets from the other genotypes were treated for 5 min as the best treatment. The paper discusses interactions of the factors, which may be interesting for others aiming to breed doubled haploid sugar beet or possibly other related plant species.

Both Nuclear Size and DNA Amount Contribute to Midblastula Transition Timing in Xenopus laevis

During early Xenopus laevis embryogenesis both nuclear and cell volumes decrease with the nuclear-to-cytoplasmic (N/C) volume ratio reaching a maximum at the midblastula transition (MBT). At the MBT, embryonic transcription is upregulated and cell cycles lengthen. Early studies demonstrated a role for the DNA-to-cytoplasmic ratio in the control of MBT timing. By altering nuclear size, we previously showed that the N/C volume ratio also contributes to proper MBT timing. Here we examine the relative contributions of nuclear size and DNA amount to MBT timing by simultaneously altering nuclear size and ploidy in X. laevis embryos. Compared to diploid embryos, haploids exhibited a delay in both zygotic gene expression and cell cycle lengthening, while diploid embryos with increased N/C volume ratios showed early expression of zygotic genes and premature lengthening of cell cycles. Interestingly, haploids with increased N/C volume ratios exhibited an intermediate effect on the timing of zygotic gene expression and cell cycle lengthening. Decreasing nuclear size in post-MBT haploid embryos caused a further delay in cell cycle lengthening and the expression of some zygotic genes. Our data suggest that both the N/C volume ratio and DNA amount contribute to the regulation of MBT timing with neither parameter being dominant.

Maternal Haploid, a Metalloprotease Enriched at the Largest Satellite Repeat and Essential for Genome Integrity in Drosophila Embryos.

The incorporation of the paternal genome into the zygote during fertilization requires chromatin remodeling. The maternal haploid (mh) mutation in Drosophila affects this process and leads to the formation of haploid embryos without the paternal genome. mh encodes the Drosophila homolog of SPRTN, a conserved protease essential for resolving DNA-protein cross-linked products. Here we characterize the role of MH in genome maintenance. It is not understood how MH protects the paternal genome during fertilization, particularly in light of our finding that MH is present in both parental pronuclei during zygote formation. We showed that maternal chromosomes in mh mutant embryos experience instabilities in the absence of the paternal genome, which suggests that MH is generally required for chromosome stability during embryogenesis. This is consistent with our finding that MH is abundantly present on chromatin throughout the cell cycle. Remarkably, MH is prominently enriched at the 359-bp satellite repeats during interphase, which becomes unstable without MH. This dynamic localization and specific enrichment of MH at the 359 repeats resemble that of Topoisomerase 2 (Top2), suggesting that MH regulates Top2, possibly as a protease for the resolution of Top2-DNA intermediates. We propose that maternal MH removes proteins specifically enriched on sperm chromatin. In the absence of that function, paternal chromosomes are precipitously lost. This mode of paternal chromatin remodeling is likely conserved and the unique phenotype of the Drosophila mh mutants represents a rare opportunity to gain insights into the process that has been difficult to study.