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Background: Human Immunodeficiency Virus type 2 (HIV-2) affects a minority of patients in Italy; nevertheless, the increasing migratory flow from higher prevalence areas led to the spread of this virus into our Country. We evaluate clinical, viro-immunological, and therapeutic characteristics of patients with HIV-2 infection and HIV-1/HIV-2 dual-infection and the early treatment impact on overall survival and incidence of AIDS events., Methods: We retrospectively analyzed all HIV-2, and HIV-1/HIV-2 positive patients followed in a large Italian clinic from January 1987 to December 2020. We recorded demographic, viro-immunological, clinical, and therapeutic data. We performed a descriptive analysis followed by a longitudinal analysis to explore the factors associated with the CD4+ lymphocyte trend; lastly, we studied the possible predictors of death and AIDS in our cohort in a multivariable model., Results: 32 subjects were enrolled, 17 (53%) HIV-2 infected and 15 (46.8%) HIV-1/HIV-2 dual-infected; 12 patients were lost to follow up, while 3 died. We found a lack of HIV-2 viremia in 12/32 subjects (37.5%). Most of the patients at baseline had a good viro-immunological profile with HIV-2 RNA <200 copies/ml and CD4+ lymphocyte >200 cell/mcl. We found a CD4+ lymphocyte improvement over time, both in the absolute number ( β 472.61, 95%CI 383.05-562.18, p<0.001) and in percentage ( β 25.28, 95%CI 21.91 - 28.66, p<0.001). Nevertheless, subjects taking cART had CD4+ lymphocyte percentage increase over time, and this trend appeared significantly better than those who did not receive therapy. Lastly, in the multivariable model CD4+, T-cell count increase was negatively associated with AIDS (HR 0.34 95%CI 0.13-0.91, p=0.032)., Conclusion: We found a higher prevalence of HIV-1/2 dual infection than in previous observations. Subjects with HIV-2 infection showed a favorable immunological condition at diagnosis, and the benefits of cART in those who received treatment are undiscussed. Moreover, our data suggest a different disease course based on age at diagnosis, as in HIV-1 infections. We encourage starting cART at diagnosis in HIV-2 patients, regardless of CD4+ lymphocyte, because even in the new cART era, CD4+ lymphocyte decrease remains the strongest predictor of death and AIDS also in this population., Competing Interests: Competing interests: The authors declare no conflict of Interest.

A hyperinflammatory syndrome (HIS) may cause a life-threatening acute respiratory distress syndrome (ARDS) in patients with COVID-19 pneumonia. A prospective series of 100 consecutive patients admitted to the Spedali Civili University Hospital in Brescia (Italy) between March 9th and March 20th with confirmed COVID-19 pneumonia and ARDS requiring ventilatory support was analyzed to determine whether intravenous administration of tocilizumab (TCZ), a monoclonal antibody that targets the interleukin 6 (IL-6) receptor, was associated with improved outcome. Tocilizumab was administered at a dosage of 8 mg/kg by two consecutive intravenous infusions 12 h apart. A third infusion was optional based on clinical response. The outcome measure was an improvement in acute respiratory failure assessed by means of the Brescia COVID Respiratory Severity Score (BCRSS 0 to 8, with higher scores indicating higher severity) at 24-72 h and 10 days after tocilizumab administration. Out of 100 treated patients (88 M, 12 F; median age: 62 years), 43 received TCZ in the intensive care unit (ICU), while 57 in the general ward as no ICU beds were available. Of these 57 patients, 37 (65%) improved and suspended noninvasive ventilation (NIV) (median BCRSS: 1 [IQR 0-2]), 7 (12%) patients remained stable in NIV, and 13 (23%) patients worsened (10 died, 3 were admitted to ICU). Of the 43 patients treated in the ICU, 32 (74%) improved (17 of them were taken off the ventilator and were discharged to the ward), 1 (2%) remained stable (BCRSS: 5) and 10 (24%) died (all of them had BCRSS≥7 before TCZ). Overall at 10 days, the respiratory condition was improved or stabilized in 77 (77%) patients, of whom 61 showed a significant clearing of diffuse bilateral opacities on chest x-ray and 15 were discharged from the hospital. Respiratory condition worsened in 23 (23%) patients, of whom 20 (20%) died. All the patients presented with lymphopenia and high levels of C-reactive protein (CRP), fibrinogen, ferritin and IL-6 indicating a HIS. During the 10-day follow-up, three cases of severe adverse events were recorded: two patients developed septic shock and died, one had gastrointestinal perforation requiring urgent surgery and was alive at day 10. In conclusion, our series showed that COVID-19 pneumonia with ARDS was characterized by HIS. The response to TCZ was rapid, sustained, and associated with significant clinical improvement., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: COPD screening guidelines in patients with HIV are lacking, and data about its under-diagnosis are still limited. This study aimed to determinate the feasibility of a case-finding program and the prevalence of COPD under-diagnosis in a large cohort of HIV-infected subjects., Methods: All out-patients attending their routine visit for HIV monitoring at Spedali Civili General Hospital in Brescia, Italy, from February 2015 to January 2016, were enrolled. The case-finding program was structured in three steps: questionnaire administration, pre-bronchodilator spirometry testing measured with a portable spirometer, and post-bronchodilator diagnostic spirometry during a pulmonology appointment., Results: A total of 1,463 subjects were included; the average age was 46.2 ± 10.3 y. Two hundred eighty-two subjects had a positive questionnaire; 190 completed portable spirometry, and approximately 34% (65 of 190 subjects) reported respiratory impairment; of these 65 subjects, 33 completed diagnostic spirometry, and 66.7% (22 of 33) showed evidence of COPD, including 2 subjects with severe airway obstruction (GOLD stage 3, according to the Global Initiative for Chronic Obstructive Lung Disease). High dropout rates were observed in our program. Individuals with COPD exacerbations showed lower CD4+ cell counts at screening compared to those without acute worsening of symptoms (534 cells/mm 3 for subjects with GOLD 1 exacerbations and 495 cells/mm 3 for subjects with GOLD 2 exacerbations vs 781 cells/mm 3 for those without acute worsening of symptoms). The positive predictive value of the COPD screening questionnaire and portable spirometry was 33.8%., Conclusions: COPD may be under-diagnosed in HIV-infected people, and case-finding programs are an urgent issue to address as part of routine practice in these individuals., (Copyright © 2019 by Daedalus Enterprises.)

With the development of combination antiretroviral therapy (cART), the first generation of perinatally HIV-infected children has reached young adulthood. A retrospective study was conducted on perinatally HIV-infected young adults after transition to adult care in Brescia (Northern Italy). Twenty-four patients were transferred to Infectious Disease outpatient Clinic from Pediatric Clinic between 2004 and 2016. Median age at transition was 18 years. 37.5% were male, and 75% were Italian. Median CD4 + T-cell count was 534 cell/μL, and 9/24 presented detectable HIV-RNA at the time of transition. At month 12 after transition, median CD4 + T-cell count was 626 cell/μL, and HIV-RNA was still detectable in 25% of patients. Nineteen patients were still in care at the end of follow-up (median of 52 months); 100% on cART, with undetectable HIV-RNA and a median CD4 + T-cell count of 716 cell/μL. After transition, cART regimen was modified in 14/19 patients (in 13 of them it was modified at least twice). Resistance testing is available for 13 patients showing resistance-associated mutations to at least one class of drugs in 9 patients. Transition to adult care is a critical point and youths present lower rates of viral suppression compared to adults. We observed 80% of viral suppression (5 young patients were lost to follow-up and considered as failures), notwithstanding social problems and resistance mutations. With the availability of more potent and better-tolerated drugs, optimization of cART is possible also in this previously difficult-to-treat group of patients. Novel tools to address adherence to cART in young adults and teenagers will also be needed.

Introduction: Osteoporosis represents one of the most frequent comorbidity among HIV patients. The current standard method for osteoporosis diagnosis is dual-energy X-ray absorptiometry. Calcaneal quantitative ultrasound can provide information about bone quality. The aims of this study are to compare these two methods and to evaluate their ability to screen for vertebral fracture., Methods: This cross-sectional study was conducted in HIV patients attending the Clinic of Infectious and Tropical Diseases of Brescia during 2014 and who underwent lumbar/femoral dual-energy X-ray absorptiometry, vertebral fracture assessment and calcaneal quantitative ultrasound. The assessment of osteoporosis diagnostic accuracy was performed for calcaneal quantitative ultrasound and for vertebral fracture comparing them with dual-energy X-ray absorptiometry., Results: We enrolled 73 patients and almost 48% of them had osteoporosis with at least one of the method used. Vertebral fracture were present in 27.4%. Among patients with normal bone measurements, we found vertebral fracture in proportion between 10% and 30%. If we used calcaneal quantitative ultrasound method and/or X-ray as screening, the percentages of possible savable dual-energy X-ray absorptiometry ranged from 12% to 89% and misclassification rates ranged from 0 to 24.6%. A combined strategy, calcaneal quantitative ultrasound and X-Ray, identified 67% of patients with low risk of osteoporosis, but 16.4% of patients were misclassified., Conclusions: We observed that patients with osteoporosis determined by calcaneal quantitative ultrasound and/or dual-energy X-ray absorptiometry have higher probability to undergo vertebral fracture, but neither of them can be used for predicting vertebral fracture. Use of calcaneal quantitative ultrasound for screening is a reasonable alternative of dual-energy X-ray absorptiometry since our study confirm that none strategy is clearly superior, but both screen tools must be always completed with X-ray., (Copyright © 2017 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.)

Cardiovascular diseases are currently a main cause of death among people living with HIV. This population-based study aimed to investigate the incidence of cardiovascular events (CVEs) in HIV-positive people and factors associated with CVEs. We performed a retrospective cohort study of the HIV-infected patients residing in the Local Health Authority of Brescia, northern Italy, from 2000 to 2012. Incidence of CVEs events in HIV-positive patients was compared with that expected in general population living in the same area, computing standardized incidence ratios (SIRs). CVEs-associated risk factors were assessed using Cox regression analysis and competing risk model of death. About 3766 HIV-infected patients were included in the study. Over the 12-year-period, we recorded 134 CVEs: 83 (61.9%) acute myocardial infarctions (CVE type-1), and 51 (38.1%) strokes (CVE type-2). A twofold increased risk (SIR = 2.02) of CVEs was found in HIV-infected patients compared to the general population. Notably, within male patients: for CVE type-1, SIR = 1.89, for CVE type-2 SIR = 2.25; within female patients: for CVE type-1, SIR = 2.91, for CVE type-2 SIR = 2.07. Age >45 years, male gender, diabetes, and total blood cholesterol >200 mg/dl were significantly associated with CVEs incidence (for all, p < .05). These results were confirmed using the competing risk model. Our cohort study confirmed the higher incidence of CVEs in HIV-positive patients, and put emphasis on the importance of traditional cardiovascular risk factors. Overall CVE risk in HIV-positive patients was twice as high as CVE risk in general population. We found a peculiar gender distribution, with a relative risk for CVE type-1 higher in HIV-positive females, and a higher CVE type-2 risk in male patients. More studies are needed in order to support these findings and to further highlight possible gender differences in the risk of developing CVEs in HIV-positive patients.

Neurocognitive disorders are emerging, probably underestimated, complications in HIV-infected people. The aim of the study was to assess neurocognitive profiles of newly detected HIV-infected patients. We performed an observational retrospective single-cohort study. Illiterates and patients with neurologic symptoms or previous psychiatric diagnosis were excluded. Neuropsychological profiles were assessed using a validated battery of neuropsychological tests. We included 206 patients; with males representing the majority of them (85%). Risk factors for HIV acquisition were unprotected sexual intercourse (homo/bisexual in 39.8% and heterosexual in 60.2%). Thirty-nine patients (18.9%) were previous injection drug users, while 41 (19.9%) were alcohol abusers. Mean education was 11.1 years (SD--standard deviation--3.7). A high prevalence of HIV-associated neurocognitive disorders (HAND, 47.1%) was present in HIV-infected patients: particularly, asymptomatic neurocognitive impairment (ANI) was found in 30.6%, mild neurocognitive disorder (MND) in 15% and HIV-associated dementia (HAD) in 1.5%. Male gender, low degree of education, AIDS diagnosis and gepatitis B virus (HBV) co-infection were factors independently associated with HAND in a multivariable logistic regression model. Our data suggest that patient-specific factors and AIDS diagnosis have a certain kind of impact in HAND occurrence. A complete neuropsychological screening must be recommended in all patients at HIV-infection diagnosis.

Background: Hepatitis B virus infection (HBV) is widespread and it is considered a major health problem worldwide. The global distribution of HBV varies significantly between countries and between regions of the world. Among the many factors contributing to the changing epidemiology of viral hepatitis, the movement of people within and between countries is a potentially important one. In Italy, the number of migrant individuals has been increasing during the past 25 years. HBV genotype D has been found throughout the world, although its highest prevalence is in the Mediterranean area, the Middle East and southern Asia. We describe the molecular epidemiology of HBV in a chronically infected population of migrants (living in Italy), by using the phylogenetic analysis., Methods: HBV-DNA was amplified and sequenced from 43 HBV chronically infected patients. Phylogenetic and evolutionary analysis were performed using both maximum Likelihood and Bayesian methods., Results and Conclusion: Of the 43 HBV S gene isolates from migrants, 25 (58.1 %) were classified as D genotype. Maximum Likelihood analysis showed an intermixing between Moldavian and foreigners sequences mostly respect to Italian ones. Italian sequences clustered mostly together in a main clade separately from all others. The estimation of the time of the tree's root gave a mean value of 17 years ago, suggesting the origin of the tree back to 1992 year. The skyline plot showed that the number of infections softly increased until the early 2005s, after which reached a plateau. Comparing phylogenetic data to the migrants date of arrival in Italy, it should be possible that migrants arrived in Italy yet infected from their country of origin. In conclusion, this is the first paper where phylogenetic analysis and genetic evolution has been used to characterize HBV sub genotypes D1 circulation in a selected and homogenous group of migrants coming from a restricted area of Balkans and to approximately define the period of infection besides the migration date.

Background: Screening migrants from areas where hepatitis B virus (HBV) infection is endemic is important to implement preventive measures in Europe. The aim of our study was to assess (1) the feasibility of point-of-care screening in a primary care clinic and (2) hepatitis B surface antigen (HBsAg) prevalence, associated risk factors, and its clinical and epidemiological implications in undocumented migrants in Brescia, northern Italy., Methods: A longitudinal prospective study was conducted from January 2006 to April 2010 to assess HBsAg reactivity and associated risk factors among consenting undocumented migrants who accessed the Service of International Medicine of Brescia's Local Health Authority. Genotyping assay was also performed in HBV DNA-positive patients., Results: Screening was accepted by 3,728/4,078 (91.4%) subjects consecutively observed during the study period, 224 (6%) of whom were found to be HBsAg-positive. HBsAg reactivity was independently associated with the prevalence of HBsAg carriers in the geographical area of provenance (p < 0.001). On the contrary, current or past sexual risk behaviors (despite being common in our sample) were not associated with HBV infection. Half of the HBsAg patients (111/224) had either hepatitis B e-antigen (HBeAg)-positive or -negative chronic HBV infection with a possible indication for treatment. HBV genotypes were identified in 45 of 167 HBV-infected patients as follows: genotype D, 27 subjects; genotype A, 8; genotype B, 5; and genotype C, 5. The geographical distribution of genotypes reflected the geographic provenance., Conclusions: Our results suggest that point-of-care screening is feasible in undocumented migrants and should be targeted according to provenance. Case detection of HBV infection among migrants could potentially reduce HBV incidence in migrants' contacts and in the general population by prompting vaccination of susceptible individuals and care of eligible infected patients., (© 2014 International Society of Travel Medicine.)

Objectives: The aim of the study was to identify variables that can influence atazanavir plasma concentration., Methods: We retrospectively analysed atazanavir trough concentration of HIV infected patients who performed therapeutic drug monitoring between October 2007 and July 2011. Qualitative variables were compared with X(2) test while continuous ones with Mann-Whitney and Student's t-test. A linear regression model was used to investigate factors influencing atazanavir plasma concentration. Therefore, we analysed the impact of cirrhosis on atazanavir pharmacokinetic variability., Results: 255 plasma samples from 179 patients were analysed. At the univariate analysis female gender (+144.4 ng/mL; p=0.05) and tenofovir (+196.8 ng/mL; p=0.002) were associated with higher atazanavir concentrations. The multivariate model confirmed these two variables (+164.6 ng/mL; p=0.02 and +150.4 ng/mL; p=0.01) as independently associated with higher atazanavir trough concentration. The analysis of cirrhotic population showed an influence of tenofovir (-255.9 ng/mL; p=0.01), increased AST (+95.3 ng/mL; p=0.09), ALT (+67.9 ng/mL; p=0.07) and creatinine (+517.2 ng/mL; p=0.04). The multivariate model confirm that tenofovir was associated with lower atazanavir trough concentration (-284.1 ng/mL; p=0.005) while AST values significantly increased atazanavir concentrations (+114.5 ng/mL; p=0.03)., Discussion: Atazanavir is a safe and manageable drug. Our results suggest that female patients tend to have higher atazanavir plasma concentration, while the effect of tenofovir needs to be better clarified.

The diagnostic attitude of western physicians toward migrants' complaints is often an unstable balance between the obstinate search for exotic tropical diseases and the overappreciation of the cultural dimensions of symptoms. Such attitude may divert attention from organic diseases. The careful assessment of all levels of possible misunderstandings (prelinguistic, linguistic, metalinguistic, cultural, and metacultural) may help the physician to discriminate between illness and disease. The long and difficult itinerary leading to the correct diagnosis of congenital myopathy in a migrant from Senegal is described, together with the barriers encountered by the caring staff.

Background: The identification and treatment of latent tuberculosis infection (LTBI) among immigrants are an effective strategy for TB control in developed countries. A new test for LTBI identification that uses more specific antigens of Mycobacterium tuberculosis is now commercially available under the brand name of QuantiFERON-TB Gold test., Objective: To compare QuantiFERON-TB Gold test to tuberculin skin testing (TST) for the detection of LTBI among immigrants from high endemic TB areas., Patients and Methods: Undocumented immigrants attending a district medical center were enrolled if they originated from high endemic TB areas, the time of arrival in Italy was < or = 5 years, had neither active TB disease nor known immunodeficiency status. The TST was applied according to standards and QuantiFERON-TB Gold test was performed following the manufacturer's instructions., Results: Hundred subjects were included in the comparative analysis. TST was positive in 44% of subjects; 15% had a positive QuantiFERON-TB Gold test result. The total agreement between TST and QuantiFERON-TB Gold test was 71%, for a kappa statistics of 0.37; agreement was 100% for TST negative results, but only 34% for TST positive ones. In the multivariate logistic regression analysis, previous BCG vaccination was independently associated with a lower chance of disagreement between the tests., Conclusion: The prevalence of LTBI among immigrants was lower when determined by QuantiFERON-TB Gold; this may be a consequence of more specific MTB antigens used. Our results suggest that QuantiFERON-TB Gold may be used as confirmatory test for TST positive immigrants candidate to preventive therapy.

Background: Populations of Drosophila melanogaster show differences in many morphometrical traits according to their geographic origin. Despite the widespread occurrence of these differences in more than one Drosophila species, the actual selective mechanisms controlling the genetic basis of such variation are not fully understood. Thermal selection is considered to be the most likely cause explaining these differences., Results: In our work, we investigated several life history traits (body size, duration of development, preadult survival, longevity and productivity) in two tropical and two temperate natural populations of D. melanogaster recently collected, and in a temperate population maintained for twelve years at the constant temperature of 18 degrees C in the laboratory. In order to characterise the plasticity of these life history traits, the populations were grown at 12, 18, 28 and 31.2 degrees C. Productivity was the fitness trait that showed clearly adaptive differences between latitudinal populations: tropical flies did better in the heat but worse in the cold environments with respect to temperate flies. Differences for the plasticity of other life history traits investigated between tropical and temperate populations were also found. The differences were particularly evident at stressful temperatures (12 and 31.2 degrees C)., Conclusion: Our results evidence a better cold tolerance in temperate populations that seems to have been evolved during the colonisation of temperate countries by D. melanogaster Afrotropical ancestors, and support the hypothesis of an adaptive response of plasticity to the experienced environment.

Since 1996, AIDS has declined in the Italian population, but cases in foreign patients, including both recent immigrants and long-term residents, have increased from 3.9% in 1995-1996 to 15.4% in 2001-2002. This increase can only be partly explained by a higher migratory flow and might reflect a delayed access to health facilities and to antiretroviral therapy in migrants. We performed a survey for the year 2003 of HIV-infected immigrants to Italy from countries outside the European Union to verify which factors might influence a lack of access to highly active antiretroviral therapy (HAART). Italian centers of infectious diseases were requested to send sociodemographic and clinical data of HIV-infected immigrant patients. A total of 553 HIV-infected immigrants (49.9% women) were evaluated, representing 6.5% of all HIV-infected patients from these centers. The mean duration of residency in Italy was 6.6 +/- 5.0 years. The country of origin was Africa (64.5%), North and South America (24.2%), Eastern Europe (7.0%), and Asia (3.8%). A total of 407 of 553 patients (73.6%) were taking antiretroviral drugs at the time of screening. Females presented a younger age (p = 0.001), a lower frequency of Centers for Disease Control (CDC) stage B/C (p = 0.008) and a more frequent heterosexual exposure to HIV (p < 0.001), while no differences were observed for time of first positive serology (p = 0.7). CD4 cell count (p = 0.9) and log plasma HIV-RNA (p = 0.1). Characteristics of HAART patients were compared to those of nontreated patients, despite a CD4 cell count less than 350 cells/mm(3). No significant difference was found for gender, country of origin, risk factor, and years of Italian residence, while legal immigrants (p = 0.018) and registered in the National Health Service (p = 0.014) were significantly more likely to receive HAART compared to illegal immigrants.

We experimentally induced different levels of instability affecting the development of specific wing regions of Drosophila melanogaster using the UAS-GAL4 system. A common index of developmental instability is fluctuating asymmetry (FA), that is, random differences between body sides of single individuals. We studied the FA in transgenic strains carrying random genomic insertions (UAS strains), as well as insertions in the regulatory region of genes involved in the organization of wing development (GAL4 strains). In addition, the expression of genes that increase (dp110 and 3622) or decrease (dPTEN) cell proliferation was ectopically induced. Our results are related to different levels of perturbation. Through the first kind of perturbation, genome integrity was compromised by the insertion of foreign DNA. In all cases, we observed a general increase in FA, although it was rarely found significant. The second kind of perturbation involved a modification of genes controlling wing development through the insertion of a GAL4 sequence in their promoter region. The third kind involved the ectopic expression of genes controlling cell proliferation. Our results show that (i) the level of FA is connected with the level of morphological perturbation induced, (ii) FA increase was higher in the wing regions that were the target of the genetic perturbation, and (iii) developmental instability was also observed in regions that were not directly addressed by the perturbation. The results were discussed on the basis of the running models about Drosophila wing development.

Molecules involved in cell adhesion can regulate both early signal transduction events, triggered by soluble factors, and downstream events involved in cell cycle progression. Correct integration of these signals allows appropriate cellular growth, differentiation and ultimately tissue morphogenesis, but incorrect interpretation contributes to pathologies such as tumor growth. The Fat cadherin is a tumor suppressor protein required in Drosophila for epithelial morphogenesis, proliferation control and epithelial planar polarization, and its loss results in a hyperplastic growth of imaginal tissues. While several molecular events have been characterized through which fat participates in the establishment of the epithelial planar polarity, little is known about mechanisms underlying fat-mediated control of cell proliferation. Here we provide evidence that fat specifically cooperates with the epidermal growth factor receptor (EGFR) pathway in controlling cell proliferation in developing imaginal epithelia. Hyperplastic larval and adult fat structures indeed undergo an amazing, synergistic enlargement following to EGFR oversignalling. We further show that such a strong functional interaction occurs downstream of MAPK activation through the transcriptional regulation of genes involved in the EGFR nuclear signalling. Considering that fat mutation shows di per se a hyperplastic phenotype, we suggest a model in which fat acts in parallel to EGFR pathway in transducing different cell communication signals; furthermore its function is requested downstream of MAPK for a correct rendering of the growth signals converging to the epidermal growth factor receptor.

We have studied several cell behaviour parameters of mutant alleles of fat (ft) in Drosophila imaginal wing disc development. Mutant imaginal discs continue growing in larvae delayed in pupariation and can reach sizes of several times those of wild-type. Their growth is, however, basically allometric. Homozygous ft cells grow faster than their twin cells in clones and generate larger territories, albeit delimited by normal clonal restrictions. Moreover, ft cells in clones tend to grow towards wing proximal regions. These behaviours can be related with failures in cell adhesiveness and cell recognition. Double mutant combinations with alleles of other genes, e.g. of the Epidermal growth factor receptor (DER) pathway, modify ft clonal phenotypes, indicating that adhesiveness is modulated by intercellular signalling. Mutant ft cells show, in addition, smaller cell sizes during proliferation and abnormal cuticular differentiation, which reflect cell membrane and cytoskeleton anomalies, which are not modulated by the DER pathway.

Selection experiments for shortening the four longitudinal veins in a wild population of Drosophila melanogaster have been performed to evaluate how a local change is integrated in the wing development. Our results show that, though many units of selection seem to exist within a given organ, these are strongly constrained within the developmental programme, in such a way that only some predictable forms are expected. The results are discussed in terms of the 'Entelechia' model proposed by Garcia-Bellido in which the intercalarity of positional values promoted by 'martial' genes in a given organ is the driving force for controlled cell proliferation.

The body sizes and shapes of poikilothermic animals generally show clinal variation with latitude. Among the environmental factors responsible for the cline, temperature seems to be the most probable candidate. In the present work we analysed natural populations of Drosophila melanogaster collected at different geographical localities to determine whether the same selective forces acting on wing development in the laboratory are also at work in the wild. We show that the temperature selection acting on wing development in the laboratory is only one of the selective forces operating in the wild. The size differences between natural populations seem to depend exclusively on cell number whereas they depend on cell area in the laboratory. The two wing compartments behave as distinct units of selection subjected to different genetic control, confirming our previous observations on laboratory populations. In addition, subunits of development defined as regions of cell proliferation centres restricted within longitudinal veins can, in turn, be considered as subunits of selection. Their interaction during development and continuous natural selection around an optimum could explain the high wing shape stability generally found in natural populations.