Perinatal physiology in cloned and normal calves: physical and clinical characteristics

Analysis of physical traits, clinical parameters, and energy metabolism of in vivo- and in vitro-derived Flemish newborn calves during the first day of life

Studies investigating physiological deviations from normality in newborn calves derived from in vitro fertilization procedures remain important for the understanding of factors that reduce calf survival after birth. The aim of this study was to investigate parameters affecting health and welfare of newborn Flemish calves derived from in vitro embryo production (IVP) in the first hours of life in comparison to in vivo-derived calves. Physical traits of newborn calves and fetal membranes (FM) were recorded soon after birth. Newborn venous blood samples were collected at several time points within the first 24 h of life for analyses of energy substrates, electrolytes, blood gases, acid-base balance, blood chemistry, and haematology. A liver biopsy was taken within the first hour after birth for analysis of gene expression of key enzymes of the fructolytic and glycolytic pathways. Newborn IVP calves were heavier and larger at birth, which was associated with heavier FM. At several time points during the first 24 h of life, IVP-derived calves had altered rectal temperature, blood gases, electrolyte concentrations, blood parameters for liver, kidney and muscle function, and acid-base balance, plasma lipid metabolism, and hemogram parameters. The relative mRNA abundances for triokinase and lactate dehydrogenase-B were greater in IVP calves. In summary, IVP-derived newborn calves were at higher risk of clinical problems after birth, which was markedly greater in heavier and larger calves. Such animals take longer to adapt to extrauterine life and should receive a special attention during the immediate neonatal period.

Epigenetic Reprogramming and Somatic Cell Nuclear Transfer

Epigenetics is an area of genetics that studies the heritable modifications in gene expression and phenotype that are not controlled by the primary sequence of DNA. The main epigenetic mechanisms are DNA methylation, post-translational covalent modifications in histone tails, and non-coding RNAs. During mammalian development, there are two global waves of epigenetic reprogramming. The first one occurs during gametogenesis and the second one begins immediately after fertilization. Environmental factors such as exposure to pollutants, unbalanced nutrition, behavioral factors, stress, in vitro culture conditions can negatively affect epigenetic reprogramming events. In this review, we describe the main epigenetic mechanisms found during mammalian preimplantation development (e.g., genomic imprinting, X chromosome inactivation). Moreover, we discuss the detrimental effects of cloning by somatic cell nuclear transfer on the reprogramming of epigenetic patterns and some molecular alternatives to minimize these negative impacts.

Exogenous surfactant replacement immediately at birth as preventive therapy for lung prematurity in neonatal lambs

Surfactant treatment is a manner to reduce alveolar superficial tension and increase pulmonary compliance in premature neonates. Thus, we aimed to analyze the effect of exogenous surfactant treatment in combination with manual ventilation for preterm lambs. We used 15 ewes and their lambs (n = 16), prematurely born at 135 days. At birth, lambs were submitted to orotracheal intubation attached to a handheld resuscitation device and randomly allocated to: Control Group (n = 5; only manual ventilation), Single Surfactant Group (n = 5; manual ventilation coupled by intratracheal administration of 100 mg/kg surfactant) and Double Surfactant Group (n = 6; surfactant volume was divided into two doses (50 mg/kg + 50 mg/kg) administrated at birth and 30 min thereafter). A complete physical exam, arterial gas analysis, blood glucose, urea and creatinine concentration and chest radiographic assessment were performed at fixed times. All lambs had decreased body temperature until 20 min after birth. However, control and double surfactant groups reached a thermic plateau after 30 min. Regardless of the time-point, control lambs had higher heart rate in comparison to treated neonates, including bradycardia in Single Surfactant Group. Single instillation led to lower oxygenation degree, compared to the Double Surfactant Group, suggesting that surfactant treatment was not able to adequately spread within the alveoli. Lambs treated with surfactant had severe impairment of aerobic activity, leading to anaerobic metabolism. All groups had hypercapnia, which can be explained by inadequate respiratory pattern and pulmonary opacity (89% of the lambs had severe or moderate lung content). In conclusion, exogenous surfactant therapy in association with manual ventilation is ineffective in reverting pulmonary immaturity of the preterm lamb, leading to less vitality, hypoxemia, delayed pulmonary clearance and high mortality rate.

DNA methylation of the endogenous retrovirus Fematrin-1 in fetal placenta is associated with survival rate of cloned calves

INTRODUCTION

The expression of retroviral envelope proteins in the placenta facilitates generation of the multinuclear syncytiotrophoblast as an outer cellular layer of the placenta by fusion of the trophoblastic cells. This process is essential for placenta development in eutherians and for successful pregnancy.

METHODS

We tested the hypothesis that alterations in DNA methylation and gene expression profiles of the endogenous retroviruses (ERVs) and genes related to epigenetic reprogramming in placenta of cloned calves result in abnormal offspring phenotypes. The fetal cotyledons in 13 somatic cell nuclear transfer (SCNT) pregnancies were collected. DNA methylation level of Fematrin-1 was analyzed using bisulfite PCR and mRNA levels of Fematrin-1, Syncytin-Rum1, DNMT1, DNMT3A, DNMT3B, TET1, TET2 and TET3 measured by RT-qPCR.

RESULTS

Methylation of Fematrin-1 in placenta of control animals produced by artificial insemination (AI) was similar to live SCNT-produced calves, but hypermethylated than dead SCNT-produced calves. The levels of mRNA differed between SCNT-produced calves and AI animals for all genes, except TET3. However, no differences were observed between the live and dead cloned calves for all genes. Moreover, no differences were found between mRNA levels of Fematrin-1 and Syncytin-Rum1.

DISCUSSION

Our results suggest that this altered DNA methylation, deregulation in the expression of ERVs and in the genes of epigenetic machinery in fetal cotyledons of cloned calves may be associated with abnormal placentogenesis found in SCNT-produced animals. Further studies characterizing other mechanisms involved in the regulation of ERVs are important to support the development of new strategies to improve the efficiency of cloning.

Nutritional impact on gene expression and competence of oocytes used to support embryo development and livebirth by cloning procedures in goats

Changes in the nutritional plan have been shown to affect oocyte quality, crucial to oocyte donors animals used in cloning. This study aimed to evaluate the impact of diets with increasing nutritional levels (maintenance diet=M; 1.3M; 1.6M; 1.9M) fed to goats for four weeks on follicular fluid composition, gene expression and oocyte competence used to cloning in goats. Donor females were superovulated for the retrieval of matured oocytes and physical measurements reported. After four weeks, groups receiving diets above maintenance increased thickness of subcutaneous adipose tissue and body weight, with higher values in 1.9M Group (P<0.05). Treatments did not affect follicular density, number of aspirated follicles, retrieved and matured oocytes. Animals from 1.3M group had lower (P<0.05) maturation rate (44.0%) and number of viable oocytes (65.3%) than M (68.8%) and 1.9M (76.0%). Follicular fluid glucose concentrations increased with nutritional levels (P=0.010), with a difference (P<0.05) between groups 1.9M (11.4±2.6mg/dL) and M (2.6±0.5mg/dL). The diet did not affect the expression of GDF9, BMP15, and BAX genes in oocytes, but BCL2 and apoptotic index were significantly higher (P<0.05) in the 1.3M and 1.6M groups than the other groups. Following the transfer of cloned embryos, one fetus was born live of a twin pregnancy in the 1.9M Group. The association between energy intake and oocyte quality suggests better nutritional use by oocytes when the maximum flow was used (1.9M), but the optimal feeding level in cloning still needs refinement.

Morphometric developmental pattern of bovine handmade cloned concepti in late pregnancy

Cloning procedures often interfere with conceptus growth and life ex utero, in a set of symptoms known as abnormal offspring syndrome (AOS). The aim of the present study was to compare the developmental pattern of in vivo-derived (IVD), IVF-derived and handmade cloning-derived (NT-HMC) Day 225 bovine concepti using established procedures. Pregnancy diagnosis was performed on Day 30 following blastocyst transfer on Day 7. Conceptus morphometry was assessed by ultrasonography on Day 51, and on Day 225 pregnant cows were killed for morphological examination of concepti. Pregnancy outcome was similar between groups, with greater pregnancy losses in the first trimester (70.6%) and smaller fetuses on Day 51 in the NT-HMC group than in the IVD (14.3%) and IVF (20.0%) groups. However, NT-HMC-derived concepti were twofold larger on Day 225 of gestation than controls. A higher frequency (63.5%) of placentomes larger than the largest in the IVD group was observed in the NT-HMC group, which may be relevant to placental function. Conceptus traits in the IVF group were similar to the IVD controls, with only slight changes in placentome types. Morphological changes in cloned concepti likely affected placental function and metabolism, disrupting the placental constraining mechanism on fetal growth in mid- to late pregnancy.

Altered DNA methylation associated with an abnormal liver phenotype in a cattle model with a high incidence of perinatal pathologies

Cloning enables the generation of both clinically normal and pathological individuals from the same donor cells, and may therefore be a DNA sequence-independent driver of phenotypic variability. We took advantage of cattle clones with identical genotypes but different developmental abilities to investigate the role of epigenetic factors in perinatal mortality, a complex trait with increasing prevalence in dairy cattle. We studied livers from pathological clones dying during the perinatal period, clinically normal adult clones with the same genotypes as perinatal clones and conventional age-matched controls. The livers from deceased perinatal clones displayed histological lesions, modifications to quantitative histomorphometric and metabolic parameters such as glycogen storage and fatty acid composition, and an absence of birth-induced maturation. In a genome-wide epigenetic analysis, we identified DNA methylation patterns underlying these phenotypic alterations and targeting genes relevant to liver metabolism, including the type 2 diabetes gene TCF7L2. The adult clones were devoid of major phenotypic and epigenetic abnormalities in the liver, ruling out the effects of genotype on the phenotype observed. These results thus provide the first demonstration of a genome-wide association between DNA methylation and perinatal mortality in cattle, and highlight epigenetics as a driving force for phenotypic variability in farmed animals.

Developmental Outcome and Related Abnormalities in Goats: Comparison Between Somatic Cell Nuclear Transfer- and In Vivo-Derived Concepti During Pregnancy Through Term

Cloning by somatic cell nuclear transfer (SCNT) is characterized by low efficiency and the occurrence of developmental abnormalities, which are rather poorly studied phenomena in goats. This study aimed at comparing overall SCNT efficiency in goats by using in vitro-matured (IVM) or in vivo-matured oocytes and fibroblast donor cells (mock transfected, transgenic, or wild type), also characterizing symptoms of the Abnormal Offspring Syndrome (AOS) in development, comparing results with pregnancies produced by artificial insemination (AI) and in vivo-derived (IVD) embryos. The SCNT group had lower pregnancy rate (18.3%, 11/60), total number of concepti (20.0%, 12/60), term births (3.3%, 2/60), and live births (1.7%, 1/60) than both the IVD (77.8%, 7/9; 155.5%, 14/9; 122.2%, 11/9; 88.8%, 8/9) and the AI (71.4%, 10/14; 121.4%, 17/14; 100%, 14/14; 78.5%, 11/14) groups, respectively (p < 0.05). No SCNT pregnancies reached term using IVM oocytes, but in vivo-matured oocytes resulted in two term transgenic cloned kids. The proportion fetal membrane (FM) weight/birth weight reflected an increase in FM size and cotyledonary enlargement in clones, for disproportionally bigger newborns in relation to cotyledonary numbers. Overall, goat cloning showed losses and abnormality patterns similar to the AOS in cloned cattle and sheep, which have not been previously well recognized in goats.

Neonatal Care and Management of Foals Derived by Somatic Cell Nuclear Transfer

There are few reports on the birth of foals resulting from equine adult somatic cell nuclear transfer (NT). On evaluation of reports of 28 live-born adult somatic-cell NT (clone) foals, 3 died within 2 weeks of birth of complications. Approximately 50 % of all reported cloned foals had complications, some requiring aggressive supportive care. The most common abnormalities reported were neonatal maladjustment syndrome, enlarged umbilical remnant, and angular deformity of the forelimbs, similar to problems described in cloned cattle. In contrast, large offspring syndrome and gross abnormalities of the fetal membranes which are described in cloned cattle are not reported in cloned foals. Reports of the health of foals produced by nuclear transfer suggest that NT foals should be treated aggressively as at-risk foals until all parameters are normal.

Incidence of abnormal offspring from cloning and other assisted reproductive technologies

In animals produced by assisted reproductive technologies, two abnormal phenotypes have been characterized. Large offspring syndrome (LOS) occurs in offspring derived from in vitro cultured embryos, and the abnormal clone phenotype includes placental and fetal changes. LOS is readily apparent in ruminants, where a large calf or lamb derived from in vitro embryo production or cloning may weigh up to twice the expected body weight. The incidence of LOS varies widely between species. When similar embryo culture conditions are applied to nonruminant species, LOS either is not as dramatic or may even be unapparent. Coculture with serum and somatic cells was identified in the 1990s as a risk factor for abnormal development of ruminant pregnancies. Animals cloned from somatic cells may display a combination of fetal and placental abnormalities that are manifested at different stages of pregnancy and postnatally. In highly interventional technologies, such as nuclear transfer (cloning), the incidence of abnormal offspring continues to be a limiting factor to broader application of the technique. This review details the breadth of phenotypes found in nonviable pregnancies, together with the phenotypes of animals that survive the transition to extrauterine life. The focus is on animals produced using in vitro embryo culture and nuclear transfer in comparison to naturally occurring phenotypes.

Avaliação ultrassonográfica da involução das estruturas umbilicais extra e intracavitárias em bezerros sadios da raça Nelore concebidos naturalmente e produtos de fertilização in vitro

Esse trabalho foi desenvolvido com o objetivo de caracterizar a involução das estruturas umbilicais em bezerros sadios da raça Nelore ao longo dos primeiros 35 dias de vida, e de comparar esse processo em bezerros concebidos por métodos naturais ou por fertilização in vitro (FIV). Quarenta bezerros foram distribuídos em dois grupos (n=20) de acordo com o método de concepção (natural ou FIV) e cada grupo foi composto por dez machos e dez fêmeas. A ultrassonografia (transdutor microconvexo de 7,5 MHz) foi empregada para examinar o conjunto das estruturas remanescentes do cordão umbilical que compõem o umbigo externo e as estruturas abdominais (veia umbilical, artéria umbilical esquerda e ducto alantóide), mensurando-se os seus diâmetros em locais definidos. Os exames foram realizados entre 24 e 36 horas de vida e aos 7, 14, 21, 28 e 35 dias de idade. Testaram-se os efeitos do sexo, da idade e do método de concepção por meio da análise de variâncias de medidas repetidas. O exame ultrassonográfico provou-se adequado para a avaliação das estruturas umbilicais extra e intracavitárias permitindo a caracterização do processo fisiológico de involução das mesmas. No umbigo externo, as veias umbilicais foram observadas como imagem individualizada até os 14 dias de vida e um conjunto de estruturas em processo de atrofia era visualizado após essa idade. No abdômen, a veia e a artéria umbilicais foram visualizadas até os 35 dias de idade e o ducto alantóide somente durante a primeira semana de vida. Essas estruturas apresentaram-se com parede hiperecóica regular e contínua e lúmen homogeneamente anecóico. O diâmetro de todas as estruturas umbilicais estudadas se reduziu continuamente ao longo do primeiro mês de vida (p<0,05), sem efeito do sexo (p>0,05). Comparados aos bezerros concebidos por métodos naturais, os produtos de FIV nasceram com os vasos umbilicais e o ducto alantóide um pouco mais calibrosos (diâmetros 1 a 3 mm maiores). Distintamente dos valores mais elevados estabelecidos em estudos prévios para os bezerros de raças européias, pode-se admitir, por fim, que nos bezerros recém-nascidos sadios da raça Nelore a espessura das estruturas que compõem o umbigo externo não deve ultrapassar 2 cm, o diâmetro da veia e da artéria umbilicais pode chegar a 1 cm e o do ducto alantóide é próximo a 0,5 cm.

Effect of calf death loss on cloned cattle herd derived from somatic cell nuclear transfer: clones with congenital defects would be removed by the death loss

To increase public understanding on cloned cattle derived from somatic cell nuclear transfer (SCNT), the present review describes the effect of calf death loss on an SCNT cattle herd. The incidence of death loss in SCNT cattle surviving more than 200 days reached the same level as that in conventionally bred cattle. This process could be considered as removal of SCNT cattle with congenital defects caused by calf death loss. As a result of comparative studies of SCNT cattle and conventionally bred cattle, the substantial equivalences in animal health status, milk and meat productive performance have been confirmed. Both sexes of SCNT cattle surviving to adulthood were fertile and their reproductive performance, including efficiency of progeny production, was the same as that in conventionally bred cattle. The presence of substantial equivalence between their progeny and conventionally bred cattle also existed. Despite these scientific findings, the commercial use of food products derived from SCNT cattle and their progeny has not been allowed by governments for reasons including the lack of public acceptance of these products and the low efficiency of animal SCNT. To overcome this situation, communication of the low risk of SCNT technology and research to improve SCNT efficiency are required.

Neonatal morbidity and mortality of 31 calves derived from somatic cloning

BACKGROUND

The neonatal period is associated with high morbidity and mortality in cloned calves.

OBJECTIVE

To describe morbidity and mortality in cloned calves from birth to 2 years of age.

ANIMALS

Thirty-one somatic cell-derived Holstein calves delivered at a veterinary teaching hospital.

METHODS

Medical files were retrospectively analyzed.

RESULTS

Four calves were stillborn. Five calves born alive had physical congenital defects. Twenty-three calves had an enlarged umbilical cord. Laboratory abnormalities included acidemia, respiratory acidosis, hyperlactatemia, anemia, stress leukogram, decreased total protein, albumin and globulins, and increased creatinine. Twenty-five calves survived the 1st hour of life. Among them, 11 stood without assistance within 6 hours of birth, 10 calves took longer than 6 hours to stand, and 4 never stood. Twenty-two calves suffered from anorexia. Twelve calves had complications arising from umbilical cord infections. Three calves developed idiopathic hyperthermia (>40°C). Eight calves suffered from gastrointestinal problems, including ruminal distension, abomasal ulcers, neonatal enteritis, intussusception, and abomasal displacement. Mortality between birth and 3 weeks of age was 32% (10/31). Causes of death and reasons for euthanasia included stillbirths, respiratory failure, and limb deformities. Mortality between 3 weeks and 2 years of age was 19% (4/21), with deaths in this group attributed to generalized peritonitis and complications arising from umbilical infections. Overall, mortality rate within 2 years of age was 14/31 (45%).

CONCLUSION AND CLINICAL IMPORTANCE

Respiratory problems, limb deformities, and umbilical infections were the most common causes of morbidity and mortality in these cloned calves.

Development of bovine embryos derived from reproductive techniques

Assisted reproduction techniques have improved agricultural breeding in the bovine. However, important development steps may differ from the situation in vivo and there is a high mortality rate during the first trimester of gestation. To better understand these events, we investigated the development of embryos and fetal membranes following fixed-time AI (FTAI), IVF and nuclear transfer (NT). The onset of yolk-sac development was not normal in cloned embryos. Later steps differed from conditions in vivo in all three groups; the yolk-sac was yellowish and juxtaposed with the amniotic membrane. Vascularisation of the chorioallantoic membrane was relatively late and low in NT gestations, but normal in the others. The overall development of the embryos was normal, as indicated by morphology and regression analysis of growth rate. However, NT conceptuses were significantly smaller, with the livers in some embryos occupying the abdominal cavity and others exhibiting heart abnormalities. In conclusion, the yolk-sac and the cardiovascular system seem to be vulnerable to morphogenetic alterations. Future studies will focus on gene expression and early vascularisation processes to investigate whether these changes may be responsible for the high incidence of intrauterine mortality, especially in clones.

Physical and clinicopathologic findings in foals derived by use of somatic cell nuclear transfer: 14 cases (2004-2008)

OBJECTIVE

To describe the health status of foals derived by use of somatic cell nuclear transfer (NT) at a university laboratory.

DESIGN

Retrospective case series.

ANIMALS

14 live-born NT-derived foals.

PROCEDURES

Medical records from 2004 through 2008 were evaluated to identify all pregnancies resulting in live-born NT-derived foals. Information obtained included gestation length, birth weight, foaling complications, gross abnormalities of the fetal membranes, appearance of the umbilicus, mentation of the foal, limb deformities, and any other abnormalities detected in the neonatal period. Clinicopathologic data were also evaluated when available. Records of 4 recipient mares during gestation were included.

RESULTS

Six foals were clinically normal for all evaluated variables. The most common abnormalities detected in the remaining 8 foals included maladjustment, enlarged umbilical remnant, and angular deformity of the forelimbs. Two foals died within 7 days after parturition; in the remaining foals, these conditions all resolved with medical or surgical management. Large offspring syndrome and gross abnormalities of the fetal membranes were not detected. The 12 surviving foals remained healthy.

CONCLUSIONS AND CLINICAL RELEVANCE

Associated problems of calves resulting from use of NT have been reported, but there are few data on the outcome of foals resulting from adult somatic cell NT in horses. Although this population of foals had a lower perinatal mortality rate than has been reported for NT-derived calves, some NT-derived foals required aggressive supportive care. Birth of foals derived from NT should take place at a center equipped to handle critical care of neonates.

Aberrant gene expression patterns in placentomes are associated with phenotypically normal and abnormal cattle cloned by somatic cell nuclear transfer

Transcription profiling of placentomes derived from somatic cell nuclear transfer (SCNT, n = 20), in vitro fertilization (IVF, n = 9), and artificial insemination (AI, n = 9) at or near term development was performed to better understand why SCNT and IVF often result in placental defects, hydrops, and large offspring syndrome (LOS). Multivariate analysis of variance was used to distinguish the effects of SCNT, IVF, and AI on gene expression, taking into account the effects of parturition (term or preterm), sex of fetus, breed of dam, breed of fetus, and pathological finding in the offspring (hydrops, normal, or other abnormalities). Differential expression of 20 physiologically important genes was confirmed with quantitative PCR. The largest effect on placentome gene expression was attributable to whether placentas were collected at term or preterm (i.e., whether the collection was because of disease or to obtain stage-matched controls) followed by placentome source (AI, IVF, or SCNT). Gene expression in SCNT placentomes was dramatically different from AI ( n = 336 genes; 276 >2-fold) and from IVF ( n = 733 genes; 162 >2-fold) placentomes. Functional analysis of differentially expressed genes (DEG) showed that IVF has significant effects on genes associated with cellular metabolism. In contrast, DEG associated with SCNT are involved in multiple pathways, including cell cycle, cell death, and gene expression. Many DEG were shared between the gene lists for IVF and SCNT comparisons, suggesting that common pathways are affected by the embryo culture methods used for IVF and SCNT. However, the many unique gene functions and pathways affected by SCNT suggest that cloned fetuses may be starved and accumulating toxic wastes due to placental insufficiency caused by reprogramming errors. Many of these genes are candidates for hydrops and LOS.

Perinatal Physiology in Cloned And Normal Calves: Hematologic And Biochemical Profiles

Although a majority of clones are born normal and apparently healthy, mortality rates of nearly 30% are described in many reports. Such losses are a major limitation of cloning technology and represent substantial economic investment as well as justifiable animal health and welfare concerns. Prospective, controlled studies are needed to understand fully the causes of neonatal mortality in clones and to develop preventive and therapeutic strategies to minimize losses. We report here the findings of studies on the hematologic and biochemical profiles of cloned and control calves in the immediate 48-h postpartum period. Cloned calves were similar to control calves for a majority of parameters studied including blood gases, concentrations of plasma proteins, minerals and electrolytes, and white blood cell, neutrophil, lymphocyte, and platelet counts. The most notable differences between clones and controls in this study were reduced red- and white-blood cell counts in clones at birth and 1 h of age. As a group, plasma electrolyte concentrations were more variable in clones, and the variability tended to be shifted either higher (sodium, chloride) or lower (potassium, bicarbonate) than in controls. Previously, we noted differences in carbohydrate parameters, the length of time required for clones to make the neonatal adaptation to life ex utero, and morphology of the cloned placenta. Taken together, our findings suggest that cloned calves experience greater difficulty adjusting to life ex utero and that further research is warranted to determine the nature of the relationship between the physiological differences noted here in clones at birth and concomitant abnormal placental morphology.