Honeybee (Apis mellifera ligustica) drone embryo proteomes Jianke Li, Yu Fang *, Lan Zhang, Desalegn Begna Institute of Apicultural Research, Chinese Academy of Agricultural Science/Key Laboratory of Pollinating Insect Biology, 1# Beigou, Xiangshan, Haidian District, Beijing 100093, China 1. Background In the honeybee society, female workers are the dominant sex. Male drones are mainly present during the mating season when their main function is limited to mating with the virgin queen. Male drones never exhibit typical worker bee behaviors such as collecting nectar, pollen brood nursing and nest construction (Klenk et al., 2004). As an evolutionary consequence to conserve food, workers expel drones out of the hive when the colonies are preparing for winter (Winston, 1987). Drones are haploid and being derived through parthenogenesis from unfertilized eggs laid by the queen. Thus they inherit just one set of chromosome from their mother. This enables the honeybee to adapt to stress factors through the haploidy–diploidy mechanism of sex determination (Beye et al., 2003). The genotype of the drone is not complicated by the presence of dominant and recessive alleles as in the case of diploid queens and workers (Javier et al., 1991). Accordingly, genes of drones are effectively homozygous at any locus (Javier et al., 1991). Drones are a potentially powerful selection tool for the genetic improvement of the honeybee as they genetically contribute equally with the queen so that the egg develops into either a queen or worker. Manipulation of drone embryos at the molecular level could produce ideal offspring to facilitate more honey or royal jelly production to satisfy human demand. Honeybee embryogenesis undergoes ten developmental stages (Fleig and Sander, 1986). During ontogenesis genetic materials can be introduced into the young egg (Amdam et al., 2003; Dearden, 2006). Honeybee workers have been successfully obtained from transgenic embryos (Aase et al., 2005). There is no doubt that unraveling the global biochemical and physiological mechanisms involved in the complex developmental process at the functional molecular level is a prerequisite for gene manipulation. Proteomic analysis of honeybee, larval development (Chan and Foster, 2008; Li et al., 2007), hypopharyngeal gland development (Feng et al., 2009) and spermathecal fluid (Baer et al., 2009) have been performed. These studies have laid the foundation for revealing drone embryogenesis and have helped us obtain a deeper insight into honeybee biology at the protein level. Since drones play critical roles in honeybee breeding, it is indispensable to perform the proteomic analysis of drone embryogenesis. The recently announced decoding of the honeybee genome (Sequencing Consortium, 2006) enables us to study honeybee gene expression in a global proteomic approach. This present study was conducted to systemically analyze protein expression profiles during drone embryonic development and provide basic information for future manipulation of male embryonic stem cells to breed honeybee that produce increased amounts of royal jelly and honey. Journal of Insect Physiology 57 (2011) 372–384 ARTICLE INFO Article history: Received 2 November 2010 Received in revised form 9 December 2010 Accepted 10 December 2010 Available online 21 December 2010 Keywords: Honeybee Drone Embryo 2-DE MALDI-TOF/MS LC-Chip/ESI-QTOF ABSTRACT Little attention has been paid to the drone honeybee (Apis mellifera ligustica) which is a haploid individual carrying only the set of alleles that it inherits from its mother. Molecular mechanisms underlying drone embryogenesis are poorly understood. This study evaluated protein expression profiles of drone embryogenesis at embryonic ages of 24, 48 and 72 h. More than 100 reproducible proteins were analyzed by mass spectrometry on 2D electrophoresis gels. Sixty-two proteins were significantly changed at the selected three experimental age points. Expression of the metabolic energy requirement-related protein peaked at the embryonic age of 48 h, whereas development and metabolizing amino acid-related proteins expressed optimally at 72 h. Cytoskeleton, protein folding and antioxidant-related proteins were highly expressed at 48 and 72 h. Protein networks of the identified proteins were constructed and protein expressions were validated at the transcription level. This first proteomic study of drone embryogenesis in the honeybee may provide geneticists an exact timetable and candidate protein outline for further manipulations of drone stem cells. Crown Copyright ß 2010 Published by Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +86 10 62591449; fax: +86 10 62591449. E-mail addresses: apislijk@126.com (J. Li), freky@163.com (Y. Fang), lovebabycyndi@126.com (L. Zhang), desalegnbegna@yahoo.co.uk (D. Begna). Contents lists available at ScienceDirect Journal of Insect Physiology journal homepage: www.elsevier.com/locate/jinsphys 0022-1910/$ – see front matter . Crown Copyright ß 2010 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jinsphys.2010.12.007