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Background: The Obstetrics and Gynecology (OB/GYN) flight at Keesler Medical Center sheltered 36 pregnant women and their families during Hurricane Katrina to ensure that appropriate medical care would be available. Ironically, the hospital's emergency generators were destroyed during the 30-foot storm surge, while one woman with a previous cesarean section went into active labor. She ultimately underwent a cesarean delivery using battery-operated flashlights for illumination. After the storm, the damage to the hospital was so extensive as to require aeromedical evacuation of the pregnant patients and their families. In addition, two OB/GYN physicians transferred to a nearby shelter on base and provided general medical care to its occupants.Conclusion: OB/GYN physicians in the military play a vital role in the care of victims of natural disasters. In addition to pregnancy-related issues, OB/GYN physicians can be expected to provide primary and emergency care to victims under austere conditions. [ABSTRACT FROM AUTHOR]

Introduction: Chimeric antigen receptor T cells (CAR-Ts) targeting CD19 represent a significant advance in treatment for patients with relapsed/refractory B-cell malignancies. Although a significant minority of recipients are women during their reproductive years, there is a paucity of data regarding pregnancy and neonatal outcomes in women previously treated with CAR-T. This is important as maternal T cells are known to cross the placenta and into breastmilk during pregnancy and breastfeeding, respectively., Case Presentation: Here we present two successful pregnancies following CAR-T therapy where both neonates were initially breastfed. These represent the first cases of neonates born following CAR-T therapy comprehensively described in medical literature., Conclusion: Pregnancy following CAR-T therapy does not appear to be associated with adverse neonatal outcomes. Further work is required to delineate the outcomes in this population., (© 2024 S. Karger AG, Basel.)

C1q deficiency is a rare inborn error of immunity characterized by increased susceptibility to infections and autoimmune manifestations mimicking SLE, with an associated morbidity and mortality. Because C1q is synthesized by monocytes, to date, four patients treated with allogeneic HSCT have been reported, with a positive outcome in three. We conducted an international retrospective study to assess the outcome of HSCT in C1q deficiency. Eighteen patients, fourteen previously unreported, from eleven referral centres, were included. Two patients had two HSCTs, thus 20 HSCTs were performed in total, at a median age of 10 years (range 0.9-19). Indications for HSCT were autoimmune manifestations not controlled by ongoing treatment in seventeen, and early development of MALT lymphoma in one patient. Overall survival (OS) was 71% and event-free survival was 59% at two years (considering an event as acute GvHD ≥ grade III, disease recurrence and death). In eleven patients HSCT led to resolution of autoimmune features and discontinuation of immunosuppressive treatments (follow-up time range 3-84 months). Five patients died due to transplant-related complications. Patients with a severe autoimmune phenotype, defined as neurological and/or renal involvement, had the worst OS (40% vs 84%; p = 0.034). Reviewing data of 69 genetically confirmed C1q deficient patients, we found that anti-Ro antibodies are associated with neurologic involvement, and anti-RNP and anti-DNA antibodies with renal involvement. In conclusion, HSCT may be a valid curative option for C1q deficiency, but careful selection of patients, with an accurate assessment of risk and benefit, is mandatory., (© 2024. The Author(s).)

Congenital athymia is a life-limiting disorder due to rare inborn errors of immunity causing impaired thymus organogenesis or abnormal thymic stromal cell development and function. Athymic infants have a T-lymphocyte-negative, B-lymphocyte-positive, natural killer cell-positive immunophenotype with profound T-lymphocyte deficiency and are susceptible to severe infections and autoimmunity. Patients variably display syndromic features. Expanding access to newborn screening for severe combined immunodeficiency and T lymphocytopenia and broad genetic testing, including next-generation sequencing technologies, increasingly facilitate their timely identification. The recommended first-line treatment is allogeneic thymus transplantation, which is a specialized procedure available in Europe and the United States. Outcomes for athymic patients are best with early diagnosis and thymus transplantation before the development of infectious and inflammatory complications. These guidelines on behalf of the European Society for Immunodeficiencies provide a comprehensive review for clinicians who manage patients with inborn thymic stromal cell defects; they offer clinical practice recommendations focused on the diagnosis, investigation, risk stratification, and management of congenital athymia with the aim of improving patient outcomes., Competing Interests: Disclosure statement A.Y.K. is supported by the Wellcome Trust (222096/Z/20/Z). F.D. is supported by an NIHR Academic Clinical Lectureship and an Academy for Medical Sciences Starter Grant. E.H. and E.G.D. are supported by a grant from the Great Ormond Street Hospital Children’s Charity. O.E.’s laboratory is supported by grants from the Swedish Research Council (2018-02752 and 2022-00781) and the Swedish state under an ALF agreement between the Swedish government and the county councils (ALFGBG-965795). A.V. is supported by a core grant from the Telethon Foundation. F.J.T.’s laboratory is supported in part by EU H2020 grant RECOMB (755170–(b)) and has received funding from the European UnionHorizon 2020 research and innovation program as well as from reNEW, the Novo Nordisk Foundation for Stem Cell Research (NNF21CC0073729). G.A. is supported by an MRC Programme Grant to GA (MR/T029765/a). and G.H. is supported by the Wellcome Trust (211944/Z/18/Z). Disclosure of potential conflict of interest: The authors declare that they have no relevant conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose of Review: C1q deficiency is a rare inborn error of immunity characterized by susceptibility to severe infections and profound immune dysregulation, with a systemic lupus erythematosus-like phenotype. The management of patients with C1q deficiency is challenged by the rarity of this condition and the wide clinical variability. This review aims to emphasize the importance of a thorough immunological and clinical characterization to help guide a personalized and comprehensive approach to patients., Recent Findings: We focus on the concept of C1q deficiency as a bridge between the monogenic form of systemic lupus erythematosus and the Mendelian type I interferonopathies. Moreover, we explore the role of new treatment strategies such as Janus-associated kinase (JAK) inhibitors and allogeneic stem cell transplantation., Summary: In this narrative review, we provide a systematic overview of C1q deficiency, starting with the description of the pathophysiological background and the variable clinical phenotype, and then exploring the different prognoses, the consequent treatment strategies and future directions., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

The effective transition from pediatric to adult care for individuals with chronic medical conditions should address the medical, psychosocial and educational needs of the cohort. The views and experiences of service users and their families are an integral component of service development. This study sought to evaluate the current provision of transition services from pediatric immunology services to adult immunology services for patients with a diagnosis of an inborn error of immunity at St. James's Hospital, Dublin. We gathered patient perspectives on the experience of the transition process using a structured survey. In addition, we adopted a micro-costing technique to estimate the cost of implementing the current standard of care for these patients. Results of a micro-costing analysis suggest that the most significant component of cost in assessing these patients is on laboratory investigation, an area where there is likely significant duplication between pediatric and adult care. Perspectives from patients suggested that the transition period went well for the majority of the cohort and that they felt ready to move to adult services, but the transition was not without complications in areas such as self-advocacy and medication management. The transition process may benefit from enhanced communication and collaboration between pediatric and adult services., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 King, Ridge, Smyth, Flinn, Leahy and Conlon.)

Acute and chronic graft-versus-host disease (GVHD) continue to present a significant challenge to physicians, accounting for considerable haematopoietic stem cell transplant (HSCT)-related morbidity and mortality, particularly those patients with steroid-refractory disease. In this review, we discuss recent advances in understanding the underlying pathophysiology, prevention and management of acute and chronic GVHD. Barriers to progress include the difficulty in obtaining high-quality evidence with sufficient patient numbers to identify optimal preventative and treatment strategies, with the heterogeneity of multiple patient, donor, graft and transplant-related factors, in addition to limited availability of human tissue to study the underlying pathophysiology, particularly in steroid-refractory disease. Continued collaborative efforts to improve our understanding of the pathophysiology involved, particularly in steroid-refractory disease, identification of biomarkers to permit risk stratification, and further well-designed randomised clinical trials are essential to help physicians determine optimal GVHD preventative and treatment strategies for each individual patient., Competing Interests: The authors declare that they have no competing interests.Dr Holtan receives research funding from Incyte and Vitrac Therapeutics. She provides clinical trial adjudication services for CSL Behring.No competing interests were disclosed., (Copyright: © 2023 Gennery AR et al.)

Haematopoietic stem cell transplantation (HSCT) is the treatment of choice for malignant haematological diseases. Despite continuous improvements in pre- and post-transplantation procedures, the applicability of allo-HSCT is limited by life-threatening complications such as graft-versus-host disease (GvHD), engraftment failure, and opportunistic infections. Extracorporeal photopheresis (ECP) is used to treat steroid resistant GvHD with significant success. However, the molecular mechanisms driving its immunomodulatory action, whilst preserving immune function, require further understanding. As ECP is safe to administer with few significant adverse effects, it has the potential for earlier use in the post-HSCT treatment of GvHD. Thus, further understanding the immunomodulatory mechanisms of ECP action may justify more timely use in clinical practice, as well as identify biomarkers for using ECP as first line or pre-emptive GvHD therapy. This review aims to discuss technical aspects and response to ECP, review ECP as an immunomodulatory treatment modality for chronic GvHD including the effect on regulatory T cells and circulating vs. tissue-resident immune cells and consider the importance of emerging biomarkers for ECP response., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Bojanic, Worel, Pacini, Stary, Piekarska, Flinn, Schell, Gennery, Knobler, Lacerda, Greinix, Pulanic and Crossland.)

Primary Immune Regulatory Disorders (PIRD) describe a group of conditions characterized by loss of normal inflammatory control and immune tolerance mechanisms, with autoimmunity as a predominant clinical feature. PIRD can arise due to defects in the number or function of regulatory T-lymphocytes, defects in the immune mechanisms required to 'turn off' inflammation such as in perforin-dependent cytotoxicity or alterations in cytokine signalling pathways. Diagnosis of PIRD is a significant challenge to physicians due to their rarity, complexity, and diversity in clinical manifestations. Many of these individual conditions lack a genotype-phenotype correlation and display incomplete penetrance. However, establishing a diagnosis is integral in optimizing patient management, including the use of individualized treatment approaches. Increasing awareness among physicians is necessary as patients are likely to present to different subspecialties. Due to the rarity of these conditions, worldwide collaboration and data-sharing is essential to improve our knowledge of the clinical spectrum and disease course in PIRD, and to optimize therapeutic strategies including identification of which patients can benefit from hematopoietic stem cell transplant., (© 2022. The Author(s).)

Acute graft-versus-host disease (aGVHD) is a significant complication of allogeneic hematopoietic stem cell transplant (HSCT) and negatively affects T cell reconstitution. Extracorporeal photopheresis (ECP) reduces aGVHD, but the mechanisms remain incompletely understood. Our objective was to examine the impact of ECP on thymopoiesis in pediatric aGVHD and the mechanisms at a cellular and transcriptional level. Sixteen pediatric HSCT patients were recruited: 6 with ECP-treated aGVHD, 5 without aGVHD, and 5 with aGVHD treated with corticosteroids only. Thymopoiesis was evaluated by measuring naive T cells, TRECs, IL-7, and T cell receptor repertoire diversity. Regulatory T cell (Treg) enumeration and function and dendritic cell (DC) enumeration and phenotype were analyzed using flow cytometry. T cell transcriptome analysis was performed on ECP patients after treatment and responders pre- and post-treatment. Four ECP responders demonstrated thymic-dependent T cell recovery, and superior median naïve T cell numbers at 8 and 12 months post-HSCT compared to the aGVHD corticosteroid group. Increased Tregs and Treg suppressive function, reduced cDC/pDC and DC co-stimulatory marker expression in ECP responders suggest upregulated peripheral tolerance; these findings were not observed in partial responders. Responder post-ECP CD3+ T cell transcriptional profile demonstrated 3333 downregulated and 364 upregulated genes, with significant downregulation of ERRα and GαS pathways, and reduced expression of pro-inflammatory and adhesion proteins.Thymic function improves with successful ECP treatment. ECP reduces T cell activation and impacts peripheral tolerance via DCs and Tregs. Differences in thymic recovery, DC, and Treg cellular patterns and the T cell transcriptome were observed between ECP responders and partial responders and require further validation and investigation in additional patients.

Extracorporeal photopheresis (ECP) is a second-line therapy in acute and chronic GVHD and solid organ transplant rejection. We report ECP use in 98 pediatric patients in seven UK centers from 2010 to 2017, the majority treated for aGVHD (73.5%). ECP was safe and well tolerated including in low body weight patients. Most patients were on multiple immunosuppressive therapies prior to ECP; 45.9% were able to reduce or stop immunosuppression with treatment. Complete or partial response was reported in almost 60%. This study supports the need to include ECP treatment data to national transplant databases to provide accurate information regarding service provision, patient outcomes, and safety., Competing Interests: The authors have no conflicts of interest to declare., (© 2020 The Authors. eJHaem published by British Society for Haematology and John Wiley & Sons Ltd.)

MHC class II deficiency is a rare, but life-threatening, primary combined immunodeficiency. Hematopoietic cell transplantation (HCT) remains the only curative treatment for this condition, but transplant survival in the previously published result was poor. We analyzed the outcome of 25 patients with MHC class II deficiency undergoing first HCT at Great North Children's Hospital between 1995 and 2018. Median age at diagnosis was 6.5 months (birth to 7.5 years). Median age at transplant was 21.4 months (0.1-7.8 years). Donors were matched family donors (MFDs; n = 6), unrelated donors (UDs; n = 12), and haploidentical donors (HIDs; n = 7). Peripheral blood stem cells were the stem cell source in 68% of patients. Conditioning was treosulfanbased in 84% of patients; 84% received alemtuzumab (n = 14) or anti-thymocyte globulin (n = 8) as serotherapy. With a 2.9-year median follow-up, OS improved from 33% (46-68%) for HCT before 2008 (n = 6) to 94% (66-99%) for HCT after 2008 (n = 19; P = .003). For HCT after 2008, OS according to donor was 100% for MFDs and UDs and 85% for HIDs (P = .40). None had grade III-IV acute or chronic graft-versus-host disease. Latest median donor myeloid and lymphocyte chimerism were 100% (range, 0-100) and 100% (range, 64-100), respectively. Latest CD4+ T-lymphocyte number was significantly lower in transplant survivors (n = 14) compared with posttransplant disease controls (P = .01). All survivors were off immunoglobulin replacement and had protective vaccine responses to tetanus and Haemophilus influenzae. None had any significant infection or autoimmunity. Changing transplant strategy in Great North Children's Hospital has significantly improved outcomes for MHC class II deficiency., (© 2020 by The American Society of Hematology.)

Acute graft-versus-host disease (aGVHD) complicates allogeneic hematopoietic stem cell transplantation (HSCT), and is treated with topical and/or systemic corticosteroids. Systemic corticosteroids and aGVHD damage thymic tissue. We compared thymopoietic effect of topical steroid therapy, corticosteroids and extracorporeal photopheresis (ECP) in 102 pediatric allogeneic HSCT patients. We categorized patients into 4 groups: - no aGVHD, aGVHD treated with topical or systemic steroid, or ECP. Naïve CD4 + CD45RA + CD27 + T-lymphocyte values at 3, 6, 9, 12months post-HSCT were recorded: for ECP patients, values were recorded at 3, 6, 9, 12months during ECP. Differences were compared using the Kruskal-Wallis test. 41 patients had no aGVHD, 23 had aGVHD treated topically or systemically (25), 13 received ECP. Rate of thymopoiesis was significantly different between all groups at all time-points post-transplant (p=0.002, p<0.001, p<0.001, p=0.001 respectively). Even mild aGVHD impairs thymopoiesis. Worst recovery was in ECP patients. Earlier institution of ECP may speed thymic recovery., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Adenosine deaminase (ADA) deficiency leads to an accumulation of toxic purine degradation by-products, most potently affecting lymphocytes, leading to adenosine deaminase-deficient severe combined immunodeficiency. Whilst most notable affects are on lymphocytes, other manifestations include skeletal abnormalities, neurodevelopmental affects and pulmonary manifestations associated with pulmonary-alveolar proteinosis. Affected patients present in early infancy, usually with persistent infection, or with pulmonary insufficiency. Three treatment options are currently available. Initial treatment with enzyme replacement therapy may alleviate acute symptoms and enable partial immunological reconstitution, but treatment is life-long, immune reconstitution is incomplete, and the reconstituted immune system may nullify the effects of the enzyme replacement. Hematopoietic stem cell transplant has long been established as the treatment of choice, particularly where a matched sibling or well matched unrelated donor is available. More recently, the use of gene addition techniques to correct the genetic defect in autologous haematopoietic stem cells treatment has demonstrated immunological and clinical efficacy. This article reviews the biology, clinical presentation, diagnosis and treatment of ADA-deficiency.

Diagnosis of Kawasaki Disease (KD) can be challenging due to lack of a diagnostic test, and some children present with 'incomplete' KD when not all diagnostic criteria are met. Treatment with intravenous immunoglobulin (IVIG) and aspirin reduces the risk of coronary artery complications. There is sub-group of patients who are resistant to IVIG/aspirin therapy and are at increased risk of complications. Recent evidence suggests that additional treatment of this high-risk group with corticosteroids is beneficial in reducing this risk. We examine the treatment and coronary artery outcomes, by retrospective review of medical records, of a cohort of 32 paediatric patients with KD admitted to a single Irish tertiary centre from January 2010-December 2014. Twenty-eight percent of patients (9/32) had an incomplete diagnosis of KD; these patients received IVIG later compared to those with a complete KD diagnosis. 15/32 (47%) had abnormal echocardiogram findings in the acute phase, 8/32 (25%) had echocardiogram abnormalities at 6-week follow-up, and 4/32 (12.5%) had persisting abnormalities. This study highlights the potential for adverse outcome in KD, the difficulty in diagnosis in 'incomplete' cases, and the need to identify children at higher risk for adverse outcome where adjunctive therapies would be most beneficial.

Allogeneic hematopoietic stem cell transplant (HSCT) is used to treat increasing numbers of malignant and non-malignant disorders. Despite significant advances in improved human leukocyte antigens-typing techniques, less toxic conditioning regimens and better supportive care, resulting in improved clinical outcomes, acute graft-versus-host disease (aGvHD) continues to be a major obstacle and, although it principally involves the skin, gastrointestinal tract, and liver, the thymus is also a primary target. An important aim following HSCT is to achieve complete and durable immunoreconstitution with a diverse T-cell receptor (TCR) repertoire to recognize a broad range of pathogens providing adequate long-term adaptive T-lymphocyte immunity, essential to reduce the risk of infection, disease relapse, and secondary malignancies. Reconstitution of adaptive T-lymphocyte immunity is a lengthy and complex process which requires a functioning and structurally intact thymus responsible for the production of new naïve T-lymphocytes with a broad TCR repertoire. Damage to the thymic microenvironment, secondary to aGvHD and the effect of corticosteroid treatment, disturbs normal signaling required for thymocyte development, resulting in impaired T-lymphopoiesis and reduced thymic export. Primary immunodeficiencies, in which failure of central or peripheral tolerance is a major feature, because of intrinsic defects in hematopoietic stem cells leading to abnormal T-lymphocyte development, or defects in thymic stroma, can give insights into critical processes important for recovery from aGvHD. Extracorporeal photopheresis is a potential alternative therapy for aGvHD, which acts in an immunomodulatory fashion, through the generation of regulatory T-lymphocytes (Tregs), alteration of cytokine patterns and modulation of dendritic cells. Promoting normal central and peripheral immune tolerance, with selective downregulation of immune stimulation, could reduce aGvHD, and enable a reduction in other immunosuppression, facilitating thymic recovery, restoration of normal T-lymphocyte ontogeny, and complete immunoreconstitution with improved clinical outcome as the ability to fight infections improves and risk of secondary malignancy or relapse diminishes.

Acute graft-versus-host disease (aGvHD) continues to be a major obstacle to allogeneic haematopoietic stem cell transplantation. Thymic damage secondary to aGvHD along with corticosteroids and other non-selective T lymphocyte-suppressive agents used in the treatment of aGvHD concurrently impair thymopoiesis and negatively impact on immunoreconstitution of the adaptive immune compartment and ultimately adversely affect clinical outcome. Extracorporeal photopheresis (ECP) is an alternative therapeutic strategy that appears to act in an immunomodulatory fashion, potentially involving regulatory T lymphocytes and dendritic cells. By promoting immune tolerance and simultaneously avoiding systemic immunosuppression, ECP could reduce aGvHD and enable a reduction in other immunosuppression, allowing thymic recovery, restoration of normal T lymphopoiesis, and complete immunoreconstitution with improved clinical outcome. Although the safety and efficacy of ECP has been demonstrated, further randomised controlled studies are needed as well as elucidation of the underlying mechanisms responsible and the effect of ECP on thymic recovery.

Objective: To compare the effect of commercially available solution and compounded ointment formulations of dorzolamide(2%)-timolol(0.5%) on intraocular pressure (IOP) of normal horses., Animals: Eighteen clinically normal horses., Procedures: A randomized, masked prospective design was used with horses divided into two equal groups. One eye of each horse was selected for topical ophthalmic treatment with either 0.2 mL of dorzolamide(2%)-timolol(0.5%) solution or 0.2 g of dorzolamide(2%)-timolol(0.5%) ointment every 12 h for 5 days. The contralateral eye of horses in both groups was untreated. Rebound tonometry was performed every 6 h starting 2 days prior to and ending 2 days after the treatment period., Results: The mean IOP reduction in eyes treated with the solution or ointment formulations was 13%. Untreated eyes in both groups experienced a lesser but still statistically significant reduction in IOP. The IOP values did not return to baseline within 48 h of the last treatment., Conclusions and Clinical Relevance: The commercially available solution and compounded ointment formulations of ophthalmic dorzolamide(2%)-timolol(0.5%) had similar effects on IOP in normal horses. Persistent IOP reduction following cessation of treatment may indicate prolonged drug effect or acclimation of horses to tonometry., (© 2014 American College of Veterinary Ophthalmologists.)

Background: When intubating newborns, clinicians aim to place the tip of the endotracheal tube (ETT) in the mid-trachea. Clinicians usually estimate the ETT insertion depth based on weight. ETT tips are often incorrectly positioned in newborns. Estimating the insertion depth based on gestation may be more accurate., Objective: To determine whether estimating the ETT insertion depth using gestation, compared to weight, results in more correctly placed ETTs., Methods: Newborn infants without congenital anomalies who were intubated orally were randomised to having their ETT insertion depth estimated using weight [insertion depth (cm) = weight (kg) + 6] or gestation [value determined from a table]. The primary outcome was correct ETT position, defined as an ETT tip between the upper border of the first thoracic vertebra (T1) and the lower border of the second thoracic vertebra (T2) on a chest X-ray. The primary outcome was determined by one paediatric radiologist who was masked to group assignment., Results: Ninety infants were enrolled and the groups were well matched. The proportion of correctly placed ETTs was not significantly different between the groups [weight, 25/49 (51%), vs. gestation, 16/41 (39%), p = 0.293]. We found no significant differences in the secondary outcomes measured., Conclusion: Estimating the ETT insertion depth in newborns using gestation compared to weight did not result in more correctly placed ETTs., (© 2015 S. Karger AG, Basel)

Identifications of ubiquinone isoprenologues are presented for isolates identified with six species of Taphrina and for isolates of the two species of Symbiotaphrina. All had Q-10 as the major ubiquinone system. The inclusion of T. populina and S. buchneri, the respective type species, establishes this as the value for these genera. Both species of Symbiotaphrina were urease positive even though, according to the literature, they are unable to utilize urea as a sole nitrogen source. The urease results for the Taphrina isolates were mixed.

The nutritional economy of the developing fruit of Pisum sativum L. (cv. Greenfeast) was studied in terms of intake of translocate, incorporation of C and N into dry matter, transpiration, and CO(2) exchanges of the fruit with its external and internal atmospheres. The environmental conditions were 12-hr days (22 C, 850 mueinsteins m(-2) sec(-1) at fruit level); 12-hr nights of 15 C.Between 6 and 30 days after anthesis, pod photosynthesis resulted in small gains of CO(2) from the external atmosphere, and assimilated most of the CO(2) respired by the fruit during the day. From then until maturity (40 days) the fruit lost CO(2) during the day. Night losses of CO(2) increased with fruit age.The gas cavity of the fruit contained 0.15 to 1.5% (v/v) CO(2). Lower levels were maintained in the day than at night. CO(2) levels were influenced by fruit age, radiant flux, and temperature. Labeled CO(2) injected into the gas cavity was fixed by the pod but not by seeds in the light, and by neither pod nor seeds in darkness. Dark-to-light or light-to-dark transfer of a fruit promoted rapid changes in CO(2) and O(2) levels of the gas space, consistent with a shift in the assimilation-respiration balance of the pod.The fruit transpired 27.6 cm(3) H(2)O per gram dry matter accumulated. Daytime ventilation was greatest 12 to 15 days after anthesis and declined as pod photosynthesis became increasingly involved in the retrieval of CO(2) respired by pod and seeds. Most, 69% by weight, of the translocate from the parent plant was converted to dry matter of seeds; nearly half, 45%, to useful seed reserves (sugar plus starch-protein-oil, 45:20:1). Illumination resulted in a fruit requiring 16% less translocate than if laying down an equal amount of dry matter in darkness.

The mature cotyledon of Pisum arvense L. comprises several distinct tissue regions; these are the epidermis, hypodermis, storage parenchyma and procambium. The storage parenchyma includes two zones: an outer abaxial zone and an inner adaxial zone. The cells of both zones contain abundant starch grains and protein bodies. Scattered through the storage tissue but increasing in frequency towards the periphery are certain cells which differ to a slight extent from the majority of the parenchyma cells. They have a more opaque, granular cytoplasm and a higher level of cytoplasmic RNA. the cotyledon has a complex, reticulate vascular system. Differentiation of the conducting elements from the procambium appears to begin about 12 hours and to be completed 48 hours after the commencement of imbibition. Differentiation of phloem preceeds that of xylem. The relationship between the timing of vascular differentiation and various physiological events in the cotyledon is discussed.Mobilization of the reserves in the storage parenchyma is initiated at the periphery of the cotyledon and proceeds inwards. There appears to be a correlation between the breakdown of the reserves and changes in DNA and RNA content of the cells.

Enzyme activity is not uniformly distributed through the cotyledon of Pisum arvense. Initially the peripheral region, certain scattered cells of the storage tissue and the procambium show a high level of activity of succinic dehydrogenase, cytochrome oxidase, acid phosphatase and esterase. Activity of acid phosphatase declines sharply after the first day of germination; activity of the other enzymes declines after about three days. In the storage tissue, where activity is lower initially, it declines after about five days and is correlated with the disappearance of the reserves. The pattern of alkaline phosphatase activity is similar except that activity is lower in the procambium but increases in the sieve-elements during differentiation of the phloem. 5-nucleotidase and glucose-6-phosphatase activity is low throughout the cotyledon but it also increases to a significant level in the sieve-elements. Activity of starch synthesizing enzymes is high in the parenchymatous bundle sheath, where they may be involved in the pathway from lipids to soluble carbohydrates.